The Disturbing Truth About Neck Threadworms and Your Itchy Horse

The Disturbing Truth About Neck Threadworms and Your Itchy Horse

disturbing-truth-feature

Look on any ivermectin or moxidectin-based wormer packet and you’ll see a long list of parasites. Tucked in neatly at the end – it’s nearly always at the end – you’ll see the words Onchocerca Microfilariae, otherwise known as neck threadworms.

Also known as neck threadworms, these critters vary in length from 6cm to 30cm (think the length of a regular ruler). Astonishingly, they live in the horse’s nuchal ligament.

Yes, the nuchal ligament. It runs the full length of the neck, from poll to withers, with a flat ligament part connecting with the cervical vertebrae.

Apparently, most horses have Onchocerca. For many they’re not a problem, but some horses develop a reaction to their microscopic larvae (the microfilariae). This is known as Onchocerciasis. The horses become itchy, mostly around the head, neck, chest, shoulders and underside of the belly. That’s why owners often make the understandable assumption that their horse has Queensland itch or sweet itch.

(This article can also be found under: www.neckthreadworms.com)

A quick introduction to neck threadworms

Original article by Jane Clothier, posted on www.thehorsesback.com, June 2013. All text and photographs (c) Jane Clothier. No reproduction without permission, sorry. Links to this page are fine.

Onchocerca is what’s known as a parasitic filarial worm (nematode). One reason these worms get relatively little attention is that they never live in the intestines. The microscopic larval form live in the horse’s skin, mostly around the head, neck, shoulders, chest and underside of the belly. It is the adult worm that later makes its home in the nuchal ligament.

The problem is global and horses in most countries have been found to have this parasite. Unfortunately for those of us who keep horses in warmer, humid climates, it’s more frequent here. The biting insect that serves as a carrier is the Culicoides fly, which is also connected to Queensland Itch (aka Sweet Itch, Summer Itch, etc.).

It’s an unfortunate coincidence of environment that leads to many cases of neck threadworms being missed, because they’re assumed to be Itch.

Does your horse have “the itch” – or neck threadworms?

It’s a humdinger of a thought. If your horse is itchy, something different could be happening to what you think is happening.

  •  Your horse has the ‘regular’ itch (ie, Queensland, sweet, whatever it’s called in your region) and are reacting to midge spit – and nothing else. (The point of this article certainly isn’t to try and say that all itch cases are due to neck threadworms. Just some.)
  •  Your horse has neck threadworms and its inflammatory reaction to them has increased its sensitivity, so it’s now reacting to fly bites everywhere – in other words, Queensland/sweet itch has been triggered as a secondary response.
  • Your horse only has neck threadworms, in which case they’re probably rubbing along the mane and particularly the base of mane, around the neck and face, under the chest and down the ventral line (under the belly), but not on the tail head – or at least, relatively little.

Are you by any chance now thinking other horses you know? If so, they might be suffering from Onchocerciasis. There’s a lot of it about.

So how do we identify neck threadworms?

A pony with the Itch and neck threadworms. It's Autumn and she's stopped rubbing out her entire mane, but is still itching that tell-tale area in front of the withers. Her coat has raised in a temporary histamine reaction to the ivermectin wormer.

A pony with the Itch and neck threadworms. It’s Autumn and she’s stopped rubbing out her entire mane – it has grown back – but is still itching that tell-tale area in front of the withers. Her coat is raised in a temporary histamine reaction to the ivermectin wormer.

Neck threadworms have a distinctive life cycle, but as is so often the case, the problem presents in  different ways, depending on the individual.

In my brumby Colo, it started with him scratching the underside of his neck on posts. That was about 3 months before I had an inkling it might be neck threadworms. How I wish I’d known  what it was at that point, so that I could have nipped the problem in the bud…

I’ve also seen it manifest as a new, previously unseen itchy and scurfy patch on the lower part of the neck of a horse who’d never been itchy. And I’ve heard of a local horse who suddenly started furiously itching his face, bang in the middle of the forehead, to the point that it bled. He had never been itchy before.

These are the classic early signs, usually recognised by the owner only through miserable hindsight. Other signs include small lumps forming along the underside of the horse and on its neck and face, weeping spots, and a scaly crest to an area of the mane through rubbing.

The base of the mane, just in front of the withers, seems to be party central where neck threadworms are concerned.

The real nastiness of neck threadworms

The microscopic larvae can travel to the eye, although this is rare.

The microscopic larvae can travel to the eye, although this is rare.

It just gets better: the larvae can travel to the horse’s eyes, where they can cause untold damage. This cheering sentence from Scott and Miller’s Equine Dermatology sums it up: “O. cervicalis microfilariae may also invade ocular tissues, where they may be associated with keratitis, uveitis, peripapillary choroidal sclerosis, and vitiligo of the bulbar conjunctiva of the lateral limbus.”

Oh heck. Nobody’s sure how common this is. All I know is that I don’t want to find out the hard way.

Consider this: in humans, a slightly different strain of Onchocerca infestation is known as River Blindness.

Please remember this detail when you’re deciding whether to worm for neck threadworms or not.

The very strange lifecycle of the neck threadworm

These worms have a complicated existence. They’re among the shapeshifters of the parasitic worm world, developing through several larval stages before reaching adulthood.

The first stage microfilariae live in the horse, close to the skin. Their numbers are highest in the spring and decrease to their lowest point in mid-winter. They live in clusters, which is why you may first notice patches of scurfy skin where the horse has started itching. This is a reaction to the dead or dying larvae.

Itching down the midline. Mine have itched neck and shoulders only - so far. (Photo courtesy of blog, Baba Yaga's Mirror)

Itching down the midline. Mine have itched neck and shoulders only – so far. (Photo courtesy of blog, Baba Yaga’s Mirror)

At this point, our good friends the culicoid flies make a contribution, by biting the horse and ingesting a good number of microfilariae along with blood. Within the fly, the larvae then develop through a further stage (or two). They are then deposited back into a horse when the flies bite. The flies can do this for an impressive 20 to 25 days after first hoovering up the larvae.

Back in a host horse, the larvae then make their way via the bloodstream to the connective tissue of the nuchal ligament, which runs along the crest of the neck. Here they moult and develop into adult worms. The adults live for around 10 years and in this time, the females release thousands of microfilariae (larvae) very year.

Original article by Jane Clothier, posted on www.thehorsesback.com, June 2013. All text and photographs (c) Jane Clothier. No reproduction without permission, sorry. Links to this page are fine.

No matter where the adult worms settle, the itchiness is caused by the microfilariae that aren’t lucky enough to be consumed by a fly and are instead left to die off.

The next part’s really not fair. The more the horse itches and breaks the skin, the more the flies will bite exactly where the microfilariae are located, before transporting them to the same or another horse, to start all over again.

Unsurprisingly, horses with most lesions have higher microfilariae counts – it’s a perfect ascending spiral of parasite-induced discomfort.

The Onchecerca life cycle lasts for 4 to 5 months.

Can we test for neck threadworms?

The microfilariae can be identified in the living horse through a biopsy of the nuchal ligament. Published veterinary research shows you won’t get any indication within 34 days of worming, so the timing is critical.

Worming with ivermectin can lead to weeping spots in the mane. This was after they'd cleared.

Worming with ivermectin can lead to weeping spots in the mane. These can be painful. This photo was taken after they’d cleared, leaving bald areas. Sometimes the hair grows back white.

A dose of ivermectin-based wormer is the quickest way to tell if your horse has them. If the microfilariae are present, the horse usually responds with intense itching – and I mean, manically intense, demented itching – around 48 to 72 hours after worming.

It may develop weeping, gunky spots at the base of the mane. (If you live in a paralysis tick area, it’s similar to the localised reaction you see in response to the ticks.) These are very specific spots around 1cm in diameter, with hair loss after they’ve erupted.

My brumby responded this way, rolling furiously and rubbing vigorously against posts. Unsurprisingly, he was also hard to handle for a few days. He was definitely sore at the base of the neck, where the weeping eruptions came out, and didn’t want to be touched there. I have to say that the scale of his reaction came as a shock to me, so take heed and be prepared with some soothing salves.

What can we do about adult neck threadworms?

Here’s the depressing answer: not much. But we can manage them.

The nuchal ligament runs from poll to wither and links with the vertebrae. Yellow = funicular part, home to neck threadworms.

The nuchal ligament runs from poll to wither and links with the vertebrae. Yellow = funicular part, home to neck threadworms. (Image copyright Sustainable Dressage.)

The adults live for 10-12 years and happily inhabit the nuchal ligament. What often happens is that the horse’s body throws down calcification around the adult worms in an attempt to isolate the foreign body. In some horses, you can feel a collection of  pea-like bumps in the nuchal ligament. In the ones that I’ve checked, this was just in front of the withers.

The slightly better news it that the worms are so fine and the lumps so small that it doesn’t seem to affect the function of the ligament, which is tough and fundamentally taut anyway. However, I’ve not yet knowingly seen a horse with a long history of neck threadworms – I’d be interested in doing so.

Heavier calcification is usually most prevalent in horses in their late teens. It figures, as the adult wormers are older, and longer. Apparently they intertwine and live in small clumps. Mid-aged horses have mainly shown inflamed tissue around live parasites.

In horses less than 5yo, the parasites can be present but there’s relatively little immunological response. So if your horse has suddenly developed itchiness at the age of 5 or 6, you could be looking at the presence of this parasite.

Original article by Jane Clothier, posted on www.thehorsesback.com, June 2013. All text and photographs (c) Jane Clothier. No reproduction without permission, sorry. Links to this page are fine.

Managing the initial outbreak

Do you worm your horses? Do you want to reduce the itching at the cost of having to worm more? I know I do, but I realise that some people can’t abide the thought of chemical wormers, or their increased use. But here’s what you can do if you want to reduce that dreadful itching and virtually eliminate the possibility of eye damage.

Unfortunately, there’s no single recommended protocol for worming against neck threadworms, so you’re in fairly uncharted territory.

  • wormerTo address the initial outbreak, the advice ‘out in the field’ is to use a regular dosage of an ivermectin-based wormer, multiple times until symptoms subside. The recommended interval I’ve seen is a week, but do check with your *equine* vet first.
  • I’ve also read forum posts by US horse owners stating that a double dosage at fortnightly intervals is the most effective treatment. It’s usually around three doses, or until symptoms subside. One reason is that lower doses do not kill off enough larvae, allowing resistance to develop amongst those that remain. Wormers are certainly tested as safe at higher dosages, but again, horses are individuals, so always check with your *equine* vet first.
  • I’ve read that an injection of ivermectin can be more effective, with off-label use of a product such as Dectomax being recommended as the heavy artillery when all else has failed. Again, do check with your *equine* vet.

Some say that an ivermectin and praziquantel wormer is more effective. One small comfort is that these wormers are available in the lower price ranges. It’s a consideration, because if you’re worming multiple horses, this won’t be a cheap time. It may even be worth looking at the large bottles of liquid wormer used by studs for greater economy.

Published research has shown that moxidectin-based wormers are equally as effective in addressing the microfilariae (but don’t double-dose with this one – only with ivermectin). That’s good, as it means you can address the neck threadworms, while covering your horse for encysted strongyles too (ivermectin wormers don’t).

Whichever option you follow, it’s worth following this worming protocol with prebiotics, probiotics and ‘buffers’ such as aloe vera to support a healthy gut lining.

More about Neck Threadworms

The questions we’re still asking about neck threadworms and how they make a horse itch – Why Thinking About Neck Threadworms Still Leaves Us Scratching Our Heads

Reducing the larval population

After the initial worming, it’s a matter of management. What you’re trying to do is keep the numbers of microfilaraie low, so that the horse’s itching is reduced. Remember, most horses show little reaction, although the parasites are present. The aim has to be to bring them down to levels the horses’ systems can deal with, while taking other measures to boost the horses’ immune system.

  • Some vets say a single dose every 6-8 weeks during the fly season.
  • Others say every 3 months, timed in accordance with the larval lifecycle, which is 4 to 5 months.
  • In humid sub-tropical zones, where all parasite burdens are dramatically higher, I’ve heard of people doing it as frequently as once a month.

Beyond that, you’re back to the barrier treatments – fly rugs, lotions and potions to deflect the flies and to insulate the skin, lotions to soften the skin and heal the lesions, fly screens on shelters during the day, etc. And don’t forget about boosting your horse’s immune system generally through sound nutritional approaches.

Why you should never use ONLY mectin wormers, even if your horse has neck threadworms, as here’s a particularly dangerous gastric worm – The Worm That Kills – And Why Only Two Worming Chemicals Can Stop It

And if we do nothing?

If we don’t address the problem one way or another, we have very itchy horses, for their entire lives.

Researchers say that the calcification in the ligaments has no effect, but you’ve got to wonder. There’s no guarantee that those scientists had a highly developed understanding of equine biomechanics. Maybe they did, but… who knows. A lot of the small amount of research available is over 20 years old and the knowledge base has since grown.

There’s a small but serious risk of damage to the eyes.

On the plus side, Onchocerciasis hasn’t been found to have any association with fistulous withers.

How to put together a program of treatment for your horse with neck threadworms (and maybe the Itch) – How to Fight the Big Fight against Neck Threadworms

To recap…

Onchocerciasis is so often masked by the itch that awareness, even in the regions where it’s rife, is low.

And in those same regions, there are so many highly prevalent and deadly parasites – the worms that cause colic, that drag down the horse’s condition, that can kill through spontaneous mass emergence from encysted larval stages – that the neck threadworm larvae simply doesn’t get much of a look-in.

To repeat, I’m not saying that all cases of itch are neck threadworms. Just that these parasites may be involved and can be a contributory factor in a heightened immunological response that leads to Queensland itch (or sweet itch, or whatever you know it as).

However, some horses definitely have neck threadworms. The earlier we can identify and manage it, the better.

We can’t eliminate the neck threadworms, but we can certainly manage the effects and make our horses’ lives more comfortable.

(c) Jane Clothier – no reproduction without permission – jane@thehorsesback.com

 

Please feel to share the link to this page – and feel very free to enter your comments at the bottom of this page. The more information in one place, the better!

 

This is a blog, not an academic article, so I've not referenced the text. However, if you want to read more, here are some of the links I've been accessing.

Equine Onchocerciasis: Lesions in the Nuchal Ligament of Midwestern US Horses. G. M. Schmidt, J. D. Krehbiel, S. C. Coley and R. W. Leid. Vet Pathol 1982 19: 16. http://vet.sagepub.com/content/19/1/16

Efficacy of ivermectin against Onchocerca cervicalis microfilarial dermatitis in horses. Herd RP, Donham JC, Am J Vet Res. 1983 Jun;44(6):1102-5. http://www.ncbi.nlm.nih.gov/pubmed/6688162

Onchocerciasis, Submitted by EquiMed Staff. http://equimed.com/diseases-and-conditions/reference/onchocerciasis

Onchocerciasis, the Neck Thread Worms and Midline Dermatitis in Horses. http://www.vetnext.com/search.php?s=aandoening&id=73060240129%20458

The Hypersensitivity of Horses to Culicoides Bites in British Columbia. Gail S. Anderson, Peter Belton and Nicholas Kleider. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1680856/pdf/canvetj00574-0044.pdf

Onchocerca in Horses from Western Canada and the Northwestern United States: An Abattoir Survey of the Prevalence of Infection, L Polley. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1790494/

Research of skin microfilariae on 160 horses from Poland, France and Spain. M.T. FRANCK et al. Am J Vet Res. 1983 Jun;44(6):1102-5. http://www.revmedvet.com/2006/RMV157_323_325.pdf

Efficacy of ivermectin against Onchocerca cervicalis microfilarial dermatitis in horses. Herd RP, Donham JC. http://www.ncbi.nlm.nih.gov/pubmed/6688162

Equine Dermatology. By Danny W. Scott, William H. Miller Jr. via Google Books

Baba Yaga’s Mirror. Personal blog. http://babayagasmirror.blogspot.com.au/2010/08/neck-thread-worms-part-2.html

Comments

  1. Peta Best says:

    Hi Jane,
    Thanks for this I have been wondering what is going on with this type of itch and when I talk to some vets about it they act as if I have no idea and say that worms won’t have that affect on the neck. so i guess is about which vet u ask.
    Cheers Peta

  2. I believe that Onchocerca Microfilariae have also been implicated in several cases of fistulous withers……
    If pressed, I’m sure I could find my references again.

    • Interesting! The information out there is so piecemeal and scattered. “Equine Dermatology” says it isn’t connected, but having seen the explosive reaction to the ivermectin, I wouldn’t be at all surprised. I daresay if an affected horse also has fistulous withers, it’s fairly self-evident.

  3. My 11yro gelding had a nasty skin condition, vets tested for everything and couldn’t find an answer. After 18months I was chatting to a friend from up northern Australia whom said to double dose using Equimax day 1, day 7 then day 14 a single dose. Within the first 72hrs my horse was beside himself (which is a clear symptom of Onchocerca), we double dosed a few times until he stopped scratching. He hasn’t scratched since – that was 2 years ago. So anything that starts to itch is double dosed!

  4. mappelbee says:

    Hi, thanks for the info. I live in a Mediterranean climate (Adelaide Hills, South Australia) and have a 3yr old with neck threadworm. He has always been itchy but when he was 2yrs the itching outburst 3 days after worming with ivermectin was intolerable, he was very dangerous to be around and it was terrifying. I did not get a correct diagnosis from two vets and it cost a great deal of money treating their wrong diagnosis. When I asked vets about the possibility of it being neck threadworm it was dismissed with the vet saying “I haven’t seen a case of neck threadworm in this area for 25yrs”. I confirmed with the vet that a double dose of ivermectin would be ok and gave it a try and as you said after about the 3rd double dose he improved, I actually used the liquid you mentioned. The vet had given me some prednisone powder with his first diagnosis to help him cope with the itch so I made sure I used this also. After the 2 weekly treatments I stretched to monthly and I am now at 2 monthly intervals but I treat him with the whole tube (he prob weighs 400kg and tube treats 600kg). He is still an itchy boy but coping. the standard dose of wormer harms the larvae but does not kill them and their antigenicity increases about 100 fold, using a double dose is more likely to kill them preventing the antigen release and explains why the treatment worked. I read 85% of horses have them but its only a problem in those that are allergic.

    Thankyou for letting me know about moxidectin, I’ve been worried about not treating for encysted strongyles. I have a worm count done regularly and he has zero, i’m a little concerned because I have not treated him for over 12 months for encysted strongyles (only used ivermectin), I hope he’ll be ok when I treat him with moxidectin.

    One of the most frustrating things in this ordeal was the fact that vets dismissed the idea because of where I live. The first vet said Right Dorsal Colitis and prescribed ulcer treatment and to change feed, this took 28 days and >$900 then when this failed to fix it I sought a second opinion and asked for a skin scraping (hoping I could find some larvae), when I told the 2nd vet I thought it was neck threadworm he said it was not, that a skin scraping was not necessary and that it was a secondary skin infection caused by ‘something’. He gave a penicillin injection and suggested I wash my 2yr old every day with betadine wash, this is when he gave me the prednisone powder (which was very helpful but not a long term solution). I work full time and it wasn’t particularly warm weather so you can imagine what a pain this was. I did this for another month, then when I went to the vet to inform him that washing was not working and that I wanted to treat for neck threadworm (from what I had read online) he dismissed it as the problem but did not mind if I gave the treatment a go as he considered it to be safe. It worked and the intense itching resolved even though he is still itchy its not remotely in the same league. The time it took to get this condition sorted was disturbing (3 months), my boy is a polite, quiet, gentle and well handled young man but he was biting at his flank causing bleeding, spinning and kicking (full double barrel) and went through the fence 4 times, thankfully he did not hurt himself but the longer it went on……….well you can imagine my distress. I guess the reason I am sharing my experience is that if anyone has a horse with an INSANE itch please test or treat for neck threadworm regardless of how many experts tell you it can’t be the problem because it’s not in your area. I hate to think about how many troubled horses go undiagnosed :(. Sorry for the essay but it was an awful time in my life, he has since been started and we are doing awesome :)

    • Oh my goodness, THANK YOU for posting this. Your experience is exactly why I want to get this awareness out there. What a truly horrendous experience for you and your poor, poor horse.

      The research I’ve read shows onchecerca microfilaraie in Canada, USA, Australia, France, Poland… simply because those are the places the researchers lived. The incidence in their samples varied enormously. In Canada (post mortem skin samples from in front of the umbilicus), they found that horses from Canada had very little OM, while the horses that had moved over from the border from the US had more. Likewise in France, the French horses showed low incidence, while the Polish imports showed more. Clearly, a horse who has neck threadworms (and may not be reacting) can travel to a new area, where an obliging midge does the honour and carries the larvae to another horse.

      The more people who know about this parasite, the better, so that experiences like yours can be avoided.

    • Peta Best says:

      Thanks so much for describing a problem of
      misdiagnosis and the way you resolved the problem. I trust that many horses will benefit from your information. I know of two at least that I will treat now. I have treated my own horses in this way and they no longer suffer. So now I will be well armed with information to go onto treat a couple of others in a larger herd that I help manage.

    • And thanks for the point about the double dose and the antigenicity. I’m updating the article with that info now.

      • mappelbee says:

        Hi Jane, thanks so much for this thread. It seems it’s going to help a lot of distressed horses and worried owners. I did forget to mention that my boy was on agistment for a while and a horse from Northern Australia (QLD) arrived whilst we were there and was paddocked near by…………funny I was worried about horse flu or hendra :(.

        Great you’ll add info about the allergenicity of the little blighters, hopefully you can find a better ref than me :) but what should also be highlighted is the fact that the itch response was much less with a double dose (as well as the only treatment), I know I was VERY scared to double dose him because of the response I got from a single dose, couldn’t imagine it twice as bad …….%$#$!!!. I also wasn’t sure if it was all due to a reaction to the wormer itself and I didn’t want to kill him with a double dose (the main reason I went back to the vet to ask if ok to double dose with ivermectin). But combined with the prednisone powder the symptoms were manageable and much, much better than the initial episode caused by a single dose.

    • I also live in the Adelaide Hills, I have an appy, now 26, bought him when he was 9, previous diagnosis of various skin issues, raw rubbed dock to name one, from a previous owner.
      When he was about 10 we had ‘the itch’, skin biopsy diagnosed onchercerca. I cant remember exactly the routine but basically it was inject with antihistamine in the evening, paste with ivermectin the following morning, at least 3 times, I think 2 weeks apart.
      Tex is now 26, over the past few years he has had an itch again, usually starts when I am away and others are caring for him – maybe not taking rugs on off as often as I would, he is a hot horse. For the past 18months when itchy he has been on a herbal preparation designed for him with success, but this time the itch is worse, he has now drawn blood, along his neck, on one side,the jaw line on the other and he is pretty hairless on the chest! This week he has been bathed in Triocil, waiting for a neem shampoo to arrive, and I have used a wet solution of Tuff Rock Poultice over the oozing sores, and upped the herbal meds to 3 x daily instead of 2 – no itch for 36 hours. The poultice seems to have been successful, the sores can still ooze therefore breathe, and so far he hasnt wiped it off. The poultice was repeated again this morning.

      • It sounds like the topical applications are really helping in managing the symptoms, while the rug is a barrier to the biting flies. The poultice will also provide a direct barrier against flies drawn to the open lesions.

        • Jane,

          Please investigate the use of the Sea Buckthorn to alleviate symptoms of itching and rubbing. When I first heard of this… I tried and then recommended it to several of my clients. The horses discontinued their pathological itching and their coats came back quickly and in bloom. It was, of course, taken daily and combined with a regular worming schedule. The powder can be unpalatable and you may need to increase it’s dosage at first and mix with molasses in their feed. There are equine liquid versions available now. Here in Texas it needs to be fed from March through October.

          Thank you for your insightful article.

    • I too had this problem with 2 of my horses at the same time. I know how hard it is and how very frustrating. And the vets are of no help and cost a bundle…times 2 I might add. Mine started over 8 years ago and only in the last 2 years have I had any effective help with it. I went down your same road, just took me longer and cost more. I now can see it in so many horses but cannot get owners to “see”. it. Wish more vets wou;d get on board!

  5. Thank you for this! I am currently dealing with a mare that is new to me and is very, very itchy! I figured it was sweet itch, and now I’m thinking it may not be. The vet had been out to see her at her previous owner’s, and determined it was Sweet Itch and put her on steroids, but it didn’t work for her. I don’t know if she was wormed. I’ll be calling the vet and trying your suggestions! Thank You!

  6. Wow, I knew about worms in the eye but not in the neck. This may be a silly question but can they be detected through a worm count? I am guessing not :S

    • No, as they’re in the bloodstream as larvae and then the connective tissue as adults, but never in the gut.

      • Bridget says:

        have deffinately found cases of them in the fat that lines the inside of the slaps of a horse under the gut reguion on post mortum, easy to pick up as they cause clusters in the fat that make it look quite bubbly in appearance

  7. Jennifer says:

    My 17-18 year old mare broke into itching with a serous fluid drip along their dorsal midline after worming with ivermectin. My vet dismissed it as a fly reaction. Could this be related?

    • Do you mean ventral midline? As the research mentions oedema there. Or the back? I don’t know which other parasites might cause reactions with ivermectin, so I couldn’t say. You’d need to organise the nuchal ligament punch biopsy if not sure.

  8. I think my horse had this issue, he is in his teens and we lived in Fl. Every summer we went threw this issue. He now has white hair from all the damage. I would worm him and it would get worse. He never had a mane in Fl. he would itch it off every summer and the winters where hot he never got any re-leaf. Now that we moved here to NC this is our first Summer with them here. Hope it doesn’t start here.

    • Good luck, Donna. If he has had Onchecerciasis, then the adults are still in him. It could be worth doing a precautionary worming mid-late Spring?

      • Hi Jane,
        I am looking into the future as the equine magazines are coming out with wormers on sale now.
        I was reading threw your post and ran across my post. I didn the double dose of Ivermection. There is quest plus on sale now as I want to take care of the bots too. Your thoughts?

  9. Rachelle says:

    I discovered neck threadworms in my 4 year old horse last year. I was on the third day of a 5 day Panacur treatment when he developed what I will call a wavy lumpy neck. I did a Google search on these symptoms and neck threadworms showed up. I followed the treatment protocol and double-dosed(by weight,very important) with Equi-max right on day 4 of what should have been the 4th treatment of Panacur and then back again 2 weeks later and just to make sure, 2 weeks after that. I did try and call my vet to see if worming this much, especially after the 3 days of Panacur would hurt my horse, but never got a return answer. So, this plan was not done on the advice of my vet, but my horse showed no signs of adverse reaction from the intense worming protocol and the wavy bumpy neck went back to normal about a week after the initial Equi-max double dose(by weight). This year, I did the double dose with The Equi-max and I am following that at 2 weeks with a Quest single dose. It is important not to double dose the Quest because of the monoxidectin in it which can be very toxic.

    • A very good point about weight, and also about moxidectin – I’ll add that in. With the ‘wavy bumpy neck’, I’m thinking that you mean bumps all over the neck, is that right? It’s good to hear that you were able to resolve the problem early on…

      • Rachelle says:

        The bumps were not all over his neck. They were more along the crest part and made that part of his neck look wavy. Looked really weird. I’ve been dealing with horses for over 40 years and never saw anything like that.

        • I can picture it now – thanks. It’s astonishing how many different reactions there are.

          I want to pin down the timescales involved in the developmental stages of this parasite. Then it should be easier to calculate whether things are happening in the first season, the second, and so on. One thing’s for sure – if the larval lifecycle is 4 months, then it all happens very fast.

    • Wrangler Jayne says:

      I’ve also seen the wavy neck you spoke of in a couple of my horses. They were very sensitive to the touch, flinching away when I ran my hand over them (uncharacteristically so). I am researching to see if I could have this neckworm problem.

  10. Bridget says:

    I have sween onchocerca outbreaks in the hind end of horses too. I also have photographs of a horse with a severe case that several vets had not been able to diagnose. In post mortem, you will find large clusters of them at the base of the wither just under the the neck ligament these clusters can often be 5+ cm in size. the worms found in the clusters are up to 10mm long and look a little like a maggot larvae.

    • Thanks Bridget! Do you mean in front of the wither or behind? I wish I could post an image in this comment box, because I have one of PM worm, with associated calcification across an area about 4cm.

  11. cindy malski says:

    My horse and I have been fighting this “damn itch” for 10 yrs. Last year after trying all the potions, blankets, fly sheets, steroids, and anything I could do for him, I had allergy tests done to the tune of 900.00 plus injection monthly of 2 shots cause they said he was allergic to just about everything, he is still a mess. It is heartbreaking to watch him suffer after putting him thru all the treatments. I had asked my vet about neck threadworms. I got a BIG no way. My horse is unrideable starting early June and lasting till end of August. He was six when I bought him and he is now 15. He started this shortly after I brought him home. I live in the U.P. of Michigan. He had a beautiful mane and tail then and looks ok during winter but no mane and very little tail til about Dec. His neck,forehead,chest and belly and base of tail are scratched raw. He rarely comes out of his stall to see the sun. I am crying right now because he suffers so and I feel like I have failed him in some way. He has all the signs of NT and I had read about it 2 or 3 yrs. ago but was told “thats not what he has”. Well, I have had enough and so has he. I am buying what I need tomorrow. This is no life for him . I will see if “my vet” will give me the prednisone to make it easier on my boy. Thank you for finally opening my eyes. I am going with my gut this time and damn the professionals.

    • Cindy, gad, I’m so sorry you’ve been going through this! Your post and that of Mapelbee, above, on their own make the venture of writing this article worthwhile. I do so hope you can get to the bottom of your horse’s problems.

      At the same time, I’m speechless that vets like yours know about onchercerca cervicalis, but don’t test for it. Isn’t it bizarre, when a couple of tubes of wormer could confirm it – and start addressing it at the same time? Or failing that, a pretty inexpensive biopsy? The knowledge is there but it’s not there, if you see what I mean.

      Please let us know how you get on, right?

  12. My fella is 3, terribly itchy. He developed his itching at about 18mths old. I’ve noticed over the last six months he as developed a calcium pea size lump under his skin at his withers, right where the saddle sits:(. I’ve tried lots of remedies. Im going to get wormer on Monday!

  13. Jennifer says:

    My horse has had a particularly itchy face, and neck recently…to the point that I can’t scratch her face enough. No scaliness or loss of hair. Do you think I should treat her with an ivermectin??

    • Hi Jennifer, my best advice would be to read the article and decide on that basis. There are still other things to consider, such as bacterial infections or other environmental irritations, such as grass allergies. If you still feel it could be neck threadworms, then do consider the protocols listed in the article. And I hope you have a supportive vet!

  14. The biggest problems with NTW is that
    1. you can’t pick it up with a fecal count check
    2. the horses do not look poorly
    3. the horses are not without energy to work.

    So even considering the horse might have a parasite would be the last thing on anyone’s mind!

    This is my experience…

    Three and a half years ago, I bought a young horse, just 18 months old when it arrived at my yard. There were absolutely no issues with this horse at all. Just 14 months later, she became impossible to groom. Miserable as all hell. Biting and kicking if you even tried to wipe her gently with a very soft cloth.

    On mentioning to my vet that my horse was developing itchy problems (just like another horse in the yard), he just shrugged it off saying that it is terrible to buy a horse with skin issues and so many Warmbloods are seeming to be suffering from skin issues. One of her stable companions had similar issues that had been put down to a food intolerance, I therefore thought that my horse had also become intolerant to certain foodstuffs. Modern day premixes…. who knows? However, I did think it very unlikely to have two horses with food intolerance issues in a small yard of 5. I managed to handle my horse and her unwillingness to be groomed etc. over the past 2+ years without putting her on cortisone. I simply refused to put her on cortisone! However, I did use a cortisone cream on occasions to ease the sensitivity.

    In the beginning there was no sign of bumps although she was would rub her neck quite aggressively in the stable. The degree of itching and rubbing fluctuated but we never saw the connection after deworming with Ivermectin, likely because the treatment initiated an increase in itches!

    About 2 months back, I was completely desperate. My horse was itching so badly that she was breaking her stable door, just from sheer force. Apart from the itches, her skin could be regarded as elephant or rhino skin, she looked like a Shar Pei dog with folds around her neck. You could take a handful of skin and it seemed to come away from the muscle beneath! She was getting mysterious swollen fetlocks but never being lame. She had numerous sores appearing on her legs but there was nothing in her camp that could have caused them. My beautiful horse was suddenly experiencing weird things and I could not account for them.

    Something set me on a mission to find a solution. I started in a completely different direction but somehow ended up reading about NTW. I was absolutely thrilled (but horrified) because finally I had found a condition that correlated with the symptoms my horse was displaying. I didn’t bother to mention to my vet but instead bought 2 doses of Ivermectin based dewormer and administered them without hesitation. I got the results I was expecting….. increased itching and rubbing and surprisingly a slight decrease in the swelling in her fetlocks. Two weeks later, I double doses again and once again I got increased itching. As I had read that the dewormer remained active for 21 days in the system, I waited four weeks on and I have now administered another double dose of Ivermectin. Finally, I am starting to see the light at the end of the tunnel. However, I know I shall probably need to do a couple more single doses on a monthly basis before I see the end result I desire.

    The sad and frustrating part about this was the reaction I got from the vets when broaching the subject. The two responses I received were “No sign of NTW in the past 20 – 30 years. Definitely can’t be NTW.” and “More likely a fungal infection.” I am feeling very frustrated by this attitude as the vets are diverting attention away and instead treating the symptoms with cortisone and in so doing causing this to become an epidemic. Grrrrrrr!

    Thanks for the fantastic article. The most complete source of information I have yet to find. I can’t believe that the reaction I got from our local vets here in Cape Town, South Africa is the same as other vets world wide! With the sheer increase in the import / export of horses throughout the world, I am amazed that this is not more of a common consideration. So I join forces with all world wide to spread the word.

    • The reaction of so many vets is really strange – they are more resistant than the worms!! Horses travel, therefore the onchocerca cervicalis they carry travels. I don’t understand why people don’t want to consider what *might* be behind the symptoms they’re seeing, when elimination is so relatively simple and cheap. It should be the first to be crossed off the list, not the last!

      Congrats on the success with your own horse – sounds like she has two strains there, with the onchocerca reticulata affecting the suspensory ligaments too. (I know you realise that – just mentioning it for the benefit of anyone who doesn’t yet.)

      • I have a friend who studied veterinary – but is practicing small animals tho. When I mentioned it to her, she returned to her University lecture notes and discovered they spanned all of half a page!

        I agree with you…. the treatment is simple and cheap. It should be Step 1 for any vet when approached about an itchy horse.

  15. I have a mare with the same problem itching on her main and neck. Would like to know if I can double dose her as she is in foal. Will double dosing harm the foal

    • Hi Liza, I’m not qualified to comment on individual cases. I’d recommend talking to an equine vet (but you may find that they’re not NT-aware), or visit this forum: Chronicle of the Horse and do a search on neck threadworms – there are numerous posts and lots of people to make suggestions. Good luck!

  16. About 16 or so years ago I had a horse with NTW, diagnosed by the local vet at the time as ‘fistula wither’! The horse had on and off itching over the years, even spreading to the saddle area which made it almost impossible to ride when it was at it’s worst. He had it in all the ‘normal’ places as well. Then in 1998 we decided to move interstate, from Victoria to South Australia, and I had both my horses taken there by interstate horse transport. Unfortunately the truck was delayed and the horses were kept in a racing stables venue on the river for an extra day.
    All seemed well when they arrived (in June) but by about August the horse that was itchy came out with all these yellow pustules ALL over his body, even inside his ears. As you could imagine he was beside himself with the itch. As I was new to the area I called the local vet who suggested scrapings to determine what sort of ‘bacteria’ or whatever it was that was causing the itch. Needless to say it came back as ‘non descript’ and to treat topically, to no avail. A short while later I was talking to some new horsey friends and they suggested to ring the local HORSE vet (of which I didn’t know about).
    I rang him straight away and he diagnosed NTW over the phone but still came out to confirm. Wow, that a relief to know what it was and yes, the treatment of worming with Ivermectin once a week for 4 weeks seemed over the top but IT WORKED!
    That particular horse has since passed away but I was always checking his body and getting on top of it immediately.
    We have since moved back to Victoria to where we originally were, even keeping my new horses at the same property for 2 years till we found our own place. Guess what? The new horses got NTW at that same property but before that neither had a history of it.
    I have since “diagnosed’ NTW to various friends and they were amazed at how easy the treatment was, even though some were a little sceptical at first.

    • Thanks Helen! There seem to be a huge variety of individual reactions.

      I think so much itching happens around the neck, shoulders, belly etc because that’s closest to where the adults live, and where they’re issuing the microfilaraie. It makes sense that midges bite elsewhere on the body too.

  17. Candace says:

    At one time I tried alternative, natural worming methods until one of my Arabian foals became really sick from a worm overload. He developed itchiness which subsequent regular wormings did not control. Like others, I tried everything and ended up keeping him on a very strict no oats diet which was somewhat effective. I heard about and tried the double dose of equimax carefully by weight when the horse was 4 – I can’t remember how often but it might have been at 10 days or 2 week intervals. The horse nearly died or so it seemed. He lost all his weight in a twinkling and was a walking skeleton for a long time. Cured the itching, though. Now I have some other young horses who are itching but I am afraid to try the Equimax. Reading the posts here I am more confident that my Arabian’s reaction was unusual and will try it again. I was keeping it at a low level of itching by promptly addressing any breaks in the skin and keeping the flies down – though they often blow in from the various neighbor’s livestock. But now I have another Arabian foal who shows symptoms and she got a double dose of Ivermectin.

    • Hi Candace

      Thanks for this story! Your Arabian’s reaction sounds very much like a release of encysted small strongyles. These can only be killed with Panacur 5-day treatments or Equest / Quest wormer. Had you used these chemical wormers previously?

      Forgive me if you had – I don’t mean to preach and am hardly qualified to do so. But I’ll quote from Dr Ann Nyland’s excellent post on the subject, as your post raises an important point about what can happen if the horse hasn’t previously been wormed with those two products.

      ” When a horse who has a lot of encysted small strongyles is wormed with a standard wormer (that is, a non-Equest or non-Panacur wormer), the standard wormer kills the small strongyles living in the lumen – the standard wormer kills the ones which are not encysted.

      “These worms then die and are passed out of the horse in the manure.

      “This is not too bad IF the horse doesn’t have many of them BUT if the horse has a lot, this is what happens next. Because a lot of small strongyles have been killed in one go, those nasty encysted small strongyles, who have been sitting safety inside the horse untouched by this standard wormer, are given the signal to emerge all at once and in big numbers, to replace the ones that the standard wormer killed.

      “So, the standard wormer kills all the small strongyles in the lumen. The dead ones pass out of the horse in the droppings. Because they are suddenly not there anymore, the encysted small strongyles (which have been completely untouched and unharmed by the standard wormer) are given the signal to replace them. So a huge amount of them emerge all at once, right through the wall of the horse’s large intestine, bringing with them nasty toxins.”

      The full post can be read here: http://www.serasfix.com/2013/06/encysted-small-strongyles-killer-worm.html
      Ann’s excellent book is “Horse and Donkey Worms and Worming”. I’ll see if she has time to come in on this discussion.

  18. Donna R Simon says:

    Well after reading this post I ordered my Ivermection. Good thing as I noticed my itchy horse that hasn’t been itchy since moving here in Aug. belly is loosing hair. So I am treating that now but I can tell that the itch is coming soon. His mane had grown all winter and is the longest it has been since I bought him 12 years ago. All my friends in Fl horses are starting to itch, we all blame the no-seeums and mosquitoes. Anyone that has done this for the first time and can help me with the protocol please post your success stories. Thanks

    • Hopefully you’ll get some information here, Donna. Unfortunately my insurance doesn’t cover individual advice :-)

      If you go to the Chronicle of the Horse forum, there are several long posts on neck threadworms there, with many individual accounts. I hope this helps!

  19. Jennifer says:

    Is it a bad sign when the itchy patch has already made a solid line across the horses belly? I rescued two horses both have the same patch and a friend of mine has a solid
    line going through her belly.

    • Hi Jennifer, I couldn’t say without seeing the horse, so I’m avoiding doing assessments at a distance! Also I’m no expert – just read the research.

      However I do think that the more widespread on the body it is, the longer it has been going on. Your horses will have all kinds of immune system issues as well if they’ve been malnourished, but I’m sure you know that :-)

      If these are recent rescues, please take a look at my reply to Candace’s post, above, and encysted small strongyles. Do worm with Panacur 5-day or Quest/Equest before moving onto the ivermectin wormers.

  20. Candace, Equimax in a horse with a heavy burden of encysted small strongyles will cause Larval Cyathostomosis. In fact, worming such a horse with any non-moxidectn or non-fenbendzole wormer will. It is all explained here: http://www.serasfix.com/2013/06/encysted-small-strongyles-killer-worm.html

  21. Wow – what an excellent site and SO informative. Thanks so much. I have been battling with my itchy horse for 5 and a half years – ever since I got him. Had him vetted and like so many others, was told it’s food related or “just one of those itchy horses”. He was put on cortisone and as I had no other answers myself, I went along with the “expert’s” advice! My poor boy ended up being denied basic things like grass, which every horse loves, and by trial and elimination he’s been on a weird diet as it appeared that certain foods did exacerbate the problem. I have since realised that the foods were never the cause, but like a person with an itchy bite, it gets worse when you jump in the shower or hot bath. It doesn’t mean you’re allergic to hot water! Not to bore you all with a long story, we finally discovered in our small yard, that NTW was the likely cause of both my horse and a friend’s in the same small yard. So with NO help from any vets, we went ahead with our own de-worming programme of Ivermectin. We have now done 3 double-doses and are finally seeing the light at the end of the tunnel. My 9 year old, who has been suffering for many years, is a really bad case and will doubtless need more de-worming, BUT we have improvement in the itching and I’ve stopped the cortisone PLUS he’s getting more normal food and not showing any overt signs of extra itching because of it! His “rhino” skin and extra folds are improving. I’ve also been giving him coconut oil for a few months now, long before the de-worming, and just for interests’ sake, it has definitely helped him have a softer, silkier coat than his stable-mate who hasn’t yet been given coconut. His temperament has remained fantastic throughout, just by the way. Seems horses are affected in all sorts of different ways. I have been fortunate in that mine is the sweetest horse and has shown no grumpiness because of it. He also has an eye impairment, which I had put down to an infection a couple of years ago, possibly an injury, but now I’m beginning to wonder if it might not also be worm related? Any thoughts on that from anyone out there? He is now vision impaired on the left side and rather spooky, but we’re handling that as best we can. Thanks again so much Jane and to all the others who have posted their personal experiences. There was a time I felt my horse was the only one in the world with this problem! Not once did my vet even suggest it could be NTW – I was even told at one time to “up the cortisone if he’s more itchy”!

    • Luce, thanks for telling us about your experience. Some people have really been through hell as a consequence of non-diagnosis. I think it takes maybe a full year to knock down the microfilaraie to the point where they’re not an issue. In my next post I’ll look at things we can do to maintain the immune system and health gut function (related, of course) throughout all of this.

  22. Megan Breuer says:

    Wow! I think this must be my ponies problem. How much and how often would you recommend dosing a 400kg pony with “IMAX Gold Wormer”? Info sheet says 1ml per 50kg’s of horse so that would make a double dose 16ml to start with. How soon after that would you worm then again?

    • Hi Megan,

      Bayer Australia who produce Imax Gold have an advice page with : http://www.farmadvisor.com.au/advisory-line

      Hopefully they’ll have a vet available who is aware of neck threadworms – the product is certainly registered for it.

      For other queries specific to your horse, I suggest googling “chronnicle of the horse neck threadworms” and you’ll come across some very long and still active forum posts, with loads of people who’ll tell you about their experiences.

      Best of luck!

      Jane

  23. Thank you Jane for an informative and very useful article. More than food for thought and action.

    • Hi Victoria, the article was certainly borne of necessity! At the very least, this is a potential cause of itching that can be eliminated, particularly in ‘itchy areas’ where parasites are rife. It won’t help all itching horses, but it will help quite a few of them, so that’s got to be a good thing.

  24. Donna R Simon says:

    Yesterday I double dosed my horses, two of them where getting the crusty line down the belly, I had just cleaned their private parts so I know it wasn’t there 3 days before. I treated it with fly spay to keep the fly’s off and calamine location seem to help with the itching and dried it out. I think I will keep an eye on them and and worm in 2 weeks again. I am so happy to find out about this issue.

  25. Hi Jane – fantastic article with concise information everyone can understand.

    I’ve used the double dose (by weight) of IMAX Gold for over four years after buying a horse I suspected had NTW. Because he came from southern NSW vets also dismissed the suggestion that NTW were the cause of the lumps all over his back and withers. He now is only mildly itchy from time to time around his face and neck.

    During my research I read the whole 50 odd pages on the COTH thread – which I’m sure is now even longer but well worth a read. :). Another horse had become so itchy he would sit like a dog and rub his belly on the ground – that stopped after the DD protocol. I passed on my experiences at various times to others who had reached the desperate stage and invariably their horses also improved.

    Have bookmarked this to pass on as needed. Thank you.

    • Thanks Kerry. There are midges everywhere, just in lower numbers in cooler zones than in the humid areas. All it takes is for one horse with onchercerca to travel from one zone to the other, and the microfilaraie can be transported by obliging midges. Why does this possibility go unrecognised, when as you say, it’s so easy to identify or rule out through worming?

  26. At last an article confirming my suspicions about the link between microfilariae and qld itch through the same insect carrier. I have done quite a bit of research already on this but this joins all the dots for me. I am not sure if my pony has the neck thread worm but he does present the symptoms except the belly itch…so far. I see no reason why I can’t treat it as outlined as it’s still quite likely what he is suffering from. A vet told me once that the only wormer to continue working through all the cycles of worms is equest gold and it certainly worked for all the other worms my OTT had over weeks and weeks. I am now going to check if it also treats microfilariae.

    • Hi Heby, that was the aim of writing this, to bring it all together in one place :-) SO pleased that it’s joining the dots for so many people.

      Equest is important because only it and Panacur 5-day address the encysted small strongyle. It’s great that your vet recognised this!

      Equest is moxidectin based – research has shown a single dose to be as effective in addressing onchocerca milofilaraie as ivermectin. It’s in that research list somewhere if you can find it! I’ve not read anyone saying that they double-dosed with it though – people are only mentioning doing that with ivermectin.

  27. Hi Jane, thank you for your information and research into this. As you know my mare Xena, you are aware that she suffers quite badly with itch pretty much all year although she does improve slightly during the cooler months. She exhibits all the symptoms, neck, shoulders, face and also the belly, sitting like a dog and rubbing her tummy, even taking off skin. I will try the DD protocol and let you know the results. If she improves I will be very grateful to you, I had never heard of neck threadworms before !

    • Hi Karen :-) I did think of Xena but didn’t know about the belly rubbing, poor girl! Having had a shining and robust Colo suddenly transform into an itching maniac mid-summer, taking half his mane out in about 2 days, it was very obvious to me that something was going on. And as brumby Raine came to me, itching, for the Orara Valley – I believe Colo picked it up from her – then I’d say there’s good local cause for you to look into it. Drop me an email if you want to discuss it more….

  28. Ulrike Kraft says:

    Hi Jane,

    thanks for this article!

    I have two itchy horses and I’m hoping to be able to help them now. I have been able to keep them comfortable with a camphor spray I make up for them, but this winter they just won’t stop scratching. Their areas are mainly ears, face, wither and shoulders, top of back and underbelly. Not on the top of the tail but next to it.

    You said:

    “Whichever option you follow, it’s worth following this worming protocol with prebiotics, probiotics and ‘buffers’ such as aloe vera to support a healthy gut lining.”

    Where can I get more information on this?

    Thanks again,

    Ulrike

    • Hi Ulrike, probiotics can be bought from equine stores (online or local). There are dozens if not hundreds of websites offering advice on building horses’ immune systems, particularly with herbs. Any product used to help horses with ulcers will also help the horse receiving a lot of worming. Again, you’ll find loads online about these. I hope this all helps your horses. Are you in Australia? We’re having a warm and wet winter in our zone – I’m sure it’s been a dreadful year for itchy horses!

      • Ulrike Kraft says:

        Hi Jane, thanks for your reply! I’m also near Lismore, NSW, Sue send me your article. The internet is a great thing! Sorry about my silly question, I just thought you might have an article on horses’ immune system too.
        My horse was itchy when I got her at the age of 2 1/2. She is rising 9 now and I treated her with spray everyday and up to twice a day in summer. It used to get better in winter but she’s a mess now. It’s hard for the spray to reach her skin with her winter coat on, even though I always rub it in. I have not been away nor will I ever be, while this is going on. In my experience, people might promise they will help and then they forget or it’s just too much for them. I wouldn’t risk my itchy horses going mad. The little pony I took on due to his itch needs daily treatment as well and also continued to scratch this winter. I’ve managed to keep them quite comfortable through out the years but it’s a lot of work and commitment. I’m still dreaming of getting them out of here but selling them is not an option as I won’t be able to make sure their hooves are looked after. I don’t want to split the herd, either. I really hope I can help them with something as simple as worming them.
        Thanks again, I soon will have a look at the rest of your website but for now I have to concentrate on the worming thing. And their immune system!

        • I hope you can help them too, Ulrike. It’s truly heart-rending. I’m sure Sue can help with the gut health side, as she’s your regular equine professional :-) I’m certainly no expert – I just write about it!

          • Ulrike Kraft says:

            Writing about it makes you an expert, Jane!
            That’s the humbleness I’m used to from good horse people. Thanks again for your good work.

          • Hello Everyone.
            I have just read everything that has been written and I would like to thank everyone for there in put. I have a 6y old Appaloosa Gelding and he has had an itch ever since I got him in 2010. My two vets and farriers suggested to wash regularly. Change diet, stock holm tar, insect rugs, insect replant’s, and many different products and nothing has worked. Poor Tonka has got in now worse than ever, His mane is the same as the picture and he has rubbed parts of it completely off. There is itching down under the midline parts of his body hair turned and hair missing at the wither. The mark under the stomach is also the same, so yes this is our problem. So I thank you all I will start immediate treatment for Neck Thread worm. My Standard Breed has never shown any itch and still after all this time nothing together with him still nothing…. So I guess it is not catching.
            Also can anyone tell me if people can catch it. I do worm both my horses every 3 months and change what brands I use so that they don’t get use to the same one. I am very pleased to have found this article from you all. I have printed it and will place it in his book. I keep a separate journal for both of my horses and everything gets written in for everything. I will keep a close watch on him and what you all have to say in the future. Thank you so much for your help for us all here. Tonka Stormy and Kym.

            • Hi Kym, the horse and human strains are entirely different. Look up ‘river blindness’ and you’ll see that it’s a huge issue for people in African river areas, also managed with ivermectin.

              You may find you need to worm your itchy horse more frequently, for a while at least.

              Most horses have this, and those in a herd with an obviously itchy onchocerca horse will also have it. However, not all will react to neck threadworms. So, do you give other horses a similar level of treatment, to prevent flies transmitting microfilaraie from heavily infested horses that don’t react, to those that do react?

              The follow-up article will help you to make choices…. hopefully!

              • Hi Jane, thanks for your reply. My Mare Stormy is in her early pregnancy, Is this safe to give her for the treatment of the neck thread worm. Can I give her regular dosage ivermectin based wormer multiple times, as I will be treating Tonka with it until all the symptoms subside. I have spoken to my vet and she doesn’t agree that this is his problem. But I am going to treat him for it as I have tried many other things that have not worked.

                • Margo Nielsen says:

                  My vet didn’t think it was the problem either, so my horses suffered for 10 months before I found this information. He gave me steroid shots for the itching and had to lance the hematoma in Cherokee’s ear (from rubbing) and that was it.
                  My horses’ condition was further aggravated by the fact that they are aged and it compromised their immune systems to the point that they became extremely reactive to bug bites, specifically gnats, but to flies too. Phoebe, the pony mule, who is the youngest at 20, had the least problem, but Romeo, a 30 year old TWH lost his entire gorgeous mane, half his tail and was bleeding in several areas. Cherokee, the 24 year old pinto, rubbed off half hishair from head to shoulder, made his butt raw and rubbed his mane and half his tail off too. You can’t lose by trying!

  29. I just finished reading the book Horse and Donkey worms and worming. By Dr A Nyland

    It is a wonder my horses are still alive. The book was very informational and I will attempt to follow her suggestions on worming. I didn’t see anything on double worming in the book, maybe I missed something. I am going to go over it again. I did double worm all my horse but in the book some horse are more affected than others and should be treated differently. After the double worming right on que two of them started to itch, not too bad though. The belly line has healed up nicely using Calamine lotion and fly spray.

    • Ann Nyland’s book is about intestinal worms, so you won’t find neck threadworms or DD in there.

      It’s always wisest to treat horses as individuals. I recommend talking about protocols with vets where possible, in case there are other issues happening with horses. (I think we need a page to honour the positive vets who help with this issue!)

  30. helen simpson says:

    Thank you for a great article. My horse had the outbreaks at the base of the mane last summer. Now I know what may have been causing it and will be watching the worming closely.

  31. I have double dosed my horse with 3 different ivermectin based dewormers 3 times in the last 10 weeks and am on the verge of double dosing yet again as she is still showing the signs of high levels of microfilaria in her skin. Interestingly enough, she is much better for 21 days immediately after deworming but in the fourth week she becomes considerably more itchy and I see her rubbing more aggressively again. I am concerned about the sheer volume of ivermectin I am putting into her system and the chance of developing resistance in other worms. Could Dr Ann Nyland possibly give me some reassurance that a 4th double deworm would not be too harmful to my horse. I understand a vet cannot diagnose in this manner but I am torn between allowing the microfilaria to increase in numbers too significantly and allowing other worms to build up resistance. What are the side effects of excessive ivermectin long term? To date, the improvement in her condition is considerable and I certainly do not want to go backwards at all.

  32. Jane,
    Thank you so much for posting this and explaining it so simply. I live in SE Texas on the gulf coast and have two aged geldings (30 & 23) and a 20 year old pony mule jenny who have been tormented with these symptoms for months… especially the boys.

    They have rubbed their manes down to nothing, and have abrasions all over their faces from scratching there. One gelding rubbed his ear so roughly that he developed a hematoma, and now his ear is bent permanently. I have tried everything to help them. When it started, the vet lanced his ear to relieve pressure and gave him a steroid shot and a double dose of antibiotics. I dosed them with Ivermectin 3 weeks in a row, and they seemed to get worse! Now I know why.

    I will do the double dose process and then once a month after that. Has anyone tried to give them a shot of Kenilog (steroid) at the beginning of this procedure to prevent the torment of the severe itching they will experience? I will call my vet on Monday and discuss this with him and let you know.

    • Margo, I’ll be interested to hear the outcome. I hope it goes well for the seniors.

    • mappelbee says:

      Hi Margo, I gave my boy prednisone powder the day before i wormed him until I saw no obvious discomfort (5-6 days). You get it from the vet, your vet may have something better. The prednisone definitely helped him cope with the itch due to and during treatment. My boy is doing fantastic compared to how he was (he’ll always be a little itchier than other horses but totally manageable). Fingers crossed for you :)

      • Mappelbee,
        Thanks. That’s what I wanted to know.
        I’ll ask my vet whether prednisone or Kenilog would be better. It was a shot of Kenilog that he gave them when he saw them in the beginning of this itching, when Cherokee damaged his ear.
        What form does prednisone come in? My vet has given me Kenilog to inject in the past for an older mare I had that suffered from arthritis (deceased now). It is a steroid. I have also given it to Romeo a couple of times in the last few years for a locking stifle. He is about 30 years old.

        • mappelbee says:

          Hi Margo, I believe Prednisone is also a steroid. it is in powder form, just add to feed, I did morning and night (it’s in sachets like bute). I’m told its what the vets in Australia give to horses suffering from allergic reactions….not a long term solution though :( Perhaps a longer lasting steroid injection would be better, If I ever have another breakout I will keep in mind. FYI I also read that anti-histamines don’t work very well in horses……

  33. Cathy whitney says:

    Great write up on neck threadworms! I found out about them last year here on the Internet, and started double dosing every 2 weeks in November through January of this year. My mare has had a very itchy belly, and a bald 1″ area in her mane. I now double dose once a month, and finally I have about 4″ growth on the bald area, and her belly no longer has an itchy line down her belly. However, she does get itchy in those two areas mildly every time I dose her, mildly. Have you ever hard of mixing DMSO with ivermectin paste and apply it topically as the die off occurs? It sounds interesting, and may stop the dying microfilariae from migrating out in the areas they normally die off in…Any opinion? Thanks, Cathy

    • Can’t help on that one, I’m afraid, Cathy! Do they migrate out? I assumed they headed towards the ligament while alive, within the subcutaneous layers. And when they’re dead, they’re dead, so why use ivermectin on the bald areas? However, I can see the value of using topical treatments such as normal itch treatments on the sore areas, which often have skin lesions, so that the flies don’t bite there. If I’ve missed something here, please let me know!

  34. Update on my 3 and now 4 babies. The 3 older horses I did one dose of double dose by weight ivermectin. It has been about 8 – 10 weeks now and they are mildly itchy. No belly rubs just starting on the chest, My horse Blackjack for 12 years itched and never had a mane. I have to tell you he has white hair where he damages his hair follicles from the constant rubbing. He also has a mane that is past his neck on to his shoulder. I haven’t seen this since I purchased him when he was 2 years old. I am so happy I found this article. Thank You Jane.

    • Oh brilliant news. That is just so good! There won’t be an instant resolution and it is going to involve keeping at it, but to see a positive result must be so encouraging!

  35. Well I finally saw the replies to my post. What you say is interesting. I’m sure I had wormed the Arabian gelding with Moxidectin (Quest). I was doing that about once a year at that time and he may have gotten the 5 day Panacur, too. I remember giving it to someone and he was the only one at that time with the long term problem. The only real improvement I saw with him was using the double dosing of Equimax – that you suggest he lost weight due to a toxic reaction involving small strongyles is interesting – but I admit I am a little confused at this point. So I have two horses now with symptoms of threadworms. I had no luck in the past with that gelding with Ivermectin in any dosage though regular worming seems to help a bit now with these two. So. Should I worm for threadworms which for me was the double dose of Equimax (Ivermectin + Praziquantel) at intervals or would I be safer using moxidectin first at the suggested intervals?

    • Hi Candace – Good to hear from you :-)

      The small strongyles suggestion was just that – a suggestion. If you’d been worming regularly with Quest or Panacur, then there wouldn’t or shouldn’t have been enough of a build-up to cause such a problem. Forgive me for wrongly assuming that you hadn’t wormed with Quest/Panacur prior to using ivermectin for the neck threadworm treatments.

      Regards future worming, I’m trying to steer clear of giving specific advice, as I’m not a vet. But with my own horses, while I’ll be primarily using ivermectin for the neck threadworms, but will keep using Equest/Quest intermittently as well. It’s partly economic as much as anything else, as there are very low cost ivermectin wormers for the frequent hits on the microfilariae.

  36. Thanks. I have gotten away from using moxidectin (Quest) lately. I will carefully resume. I had a thought. We never had much trouble initially with parasites of any kind as we did not live near any other livestock (vet confirmed). I took a mare for live cover and to my annoyance she came back with those cattle cluster flies and I have had trouble ever since. IT WAS HER SON WHO HAD THE HUGE PARASITE LOAD. All of my foals since then have had problems even though I try to be so careful but not excessive with the worming. Perhaps with ya’lls advice I can reduce the effects. Unfortunately we are now surrounded by cows, donkeys, llamas and when the wind blows from their direction we get bot flies from the donkeys on the West and those cow flies from the cows in the East : (

    • My horses are with 10 cows and one Donkey, I had this issue way before they were with any cattle. I double dosed them several months ago when I read this article. I have always wormed my horses on a regular basis but it would get worse after I did so. My horse never had a mane for the last 12 years, he would rub it off every summer and if we had a hot winter in Fl. it would never come back. Now it is well past his shoulder and summer is almost over. I am so excited I found this article. I also purchased the book put out by Dr. A Nyland Horses and Donkey Worms and worming. Very helpful too. Hope this was helpful.

      • Hi Donna, Of course a horse can have threadworms without being exposed to cows. As I said, I now think a mare of mine picked up the threadworms (and some cow flies) when she went out to be bred. I believe the cow flies spread the threadworms from horse to horse … and other things like pigeon fever …

  37. Cathy whitney says:

    Jane, I read a brief thread on the chronofhorse site. Someone mentioned in late July to place ivermectin paste on affected area followed by DMSO(to help deliver it) to get to the neck threadworms that were not killed by the internal wormer. There wasn’t a lot more discussion on the idea..I re-read it and I mis-spoke on it was to target those dying off. It is an interesting idea. In reading a little more on DMSO, I also wonder if applying it with steroid cream if it would help to get it a bit deeper in to tissue that is itchy from the die off?

  38. Ulrike Kraft says:

    I love reading the success stories! It gives me hope. My itchy horses are about to get their 3rd double dose today. I did them on day 1, 7 and today is day 14. Do you think I’m overdoing it? Donna, it sounds like you had to do it only once?

    • Yes I have only done it once, just remember they get itchier after the worming so don’t think that is a sign of needing to worm more.
      Two of the horses have started itching on their chest but I have just put calamine lotion on and keep them in fly spray. I got the book by Dr. Ann Nyland but she doesn’t go over neck thread worms too much. She worms according to climate and the horse as they are all different. Her book is very useful.

      • Ulrike Kraft says:

        Thanks for your reply Donna! I didn’t give them their 3rd dose now. I’m thinking of double dosing my other horses too, because their manes are short around the withers. They show no signs of itch other than that. I have Dr. Ann Nyland’s book.

  39. Rebecca smit says:

    Hey,

    My 13 year old thoroughbred gelding got this over the summer and I wormed every 21 days with ammo wormer until where no more sings of the worm. Then I treated the marks on his neck and face with a mixture of Benadine and antiseptic solution three times a day for 6 weeks. This has seemed to keep everything under control and he is now only itchy after he sweats.

    When he got it I thought it was sweet itch too, but he had never itched before. A lady at my riding school took one look at him and told me it was hook worm. Then I did research and there is nothing really out there. So thank you for putting this up and making the information more accessible.

  40. I too have been dealing with these exact symptoms in increasing amounts for over 4 years now. I have had potential diagnoses of Qld itch, tick bite allergy and rain rot. I have tried various treatments including a cattle lice product to keep the bugs away – that nearly earned me an a double barrel to the head! My poor boy has suffered tremendously and I feel like the RSPCA will come knocking on my door for neglect. Looking at photographs of cases of NTW and hearing everyone’s descriptions definitely tells me this is what he is suffering from. I now have no doubt in my mind.

    When I bought him he had a long, thick, luxurious mane, forelock and tail. At his worst he had none, but a few wisps left. He regularly has patches of hair missing on his face and neck and sometimes will ooze blood from rubbing. He is BADLY affected around the anus and tail, although its possible he may have pinworm as well! Rugging him to physically prevent as much damage from the mad rubbing due to the intense itch has definitely helped regrow a couple of inches of mane, but no forelock of course. He has thickened skin and at times has looked like the old “Michelan tyre man”!

    I intend to follow the protocol of Quest followed by DD with Ivermectin. Jane – you mentioned interest in an older horse who’s suffered over time. My boy is a 10 y.o. arab who’s itched for over 4 years. Would you like photos/video before, during and after to add to this article?

    • Hi Jo-Anne, I’m working on the follow-up now, “Life after worming”, :-). I’d love to see some photos and could probably use them in the next article. Thank you!

      One thing I’m covering is that these horses can develop symptoms of ‘typical’ itch. The horse is reacting to the michrofilaraie that have been vectored in the culicoid flies’ mouth and that are deposited in the saliva when the flies bite. Is it surprising that the horses then become hypersensitive to culidoid fly saliva, full-stop? It makes sense: the immune system is simply doing its job. This has happened with my boy who has never been itchy in 5 years, and who is now itching his tail area and spine as well.

      I do have to wonder, also, why culicoid flies carrying microfilaraie would only bite on the head and ventral areas, when the reactions of sweet itch horses show that the flies bite everywhere? So that’s an unanswered question for me… perhaps it’s a matter of population density, as it’s presumably the adult worms that shed the stage 1 eggs and then larvae… picked up from lesions in the mane by the flies. Just thinking aloud there!

      My horse also itched his tail head. I used Strategy for pinworms (poor boy, yet another wormer), but to no avail. So now I think it’s a matter of building up the immune system even more, while knocking the OM numbers down.

      • I love you “thinking out loud”:) I have done that since I first read your article. SEE post below, today and yesterday. I think that as you mentioned, certain horses are more sensitive to this condition than others and I BELIEVE it has to do with the condition of their immune system also. I adopted a mustang in poor condition and scared of fly spray/any spray! So the process, without wormers, because of her condition, has been long and laborious (sp?). For years I have been chemical free on the farm. My addition of L-Lysine to horse feed has kept all very healthy and given this girl a sheen, despite the sores. I have “stepped” up my dose of daily food grade DE for her, since reading this article and she has shown improvement. (DE can be dusted on as an effective parasitic control method also) A full body wipe of Calendula powder, aloe gel, natural Vit.E oil and pyrethrin liquid relieves the red and itching. I wish I had a better beginning picture of her misery, but I guess I just didn’t want her and I to remember it:) NOW, cool thing you mentioned also…..the calcium deposits around the adult worm…well, I remember someone telling me that horses with “knobby knees” are usually suffering from some kind of skin condition. WELL, she will sometimes look less inflamed inside/cranial of hock/ankle after a massage or Light treatment and this could be a result of moving the calcification. I know this worm should be at the neck area, but since the larvae travel, maybe the worm will stagnate at other tendons/ligaments in the body. Therefore the itching/sores elsewhere. This mare was raw and bleeding in many areas of her body last summer when I first saw her. Her owner said “summer itch” was the cause. ** Sorry for the long post, but I think a lot about pony-type things with all the stalls I have to do everyday:)

        • Keeping on topic, Onchocerca Reticulata is a slightly different strain that migrates to the suspensory ligaments in the lower legs of horses. I doubt it would cause swelling or fluid around the knees and, as these worms are microscopic, it’s unlikely you’d notice the calcification until it had been present for many years.

  41. Allergic reactions to bugs in general (fleas/ticks and so on) are often said to be due to the saliva, so not at all surprising that a generalised allergy could develop. Even in humans its a very under researched problem (my husband suffers from tick bite allergy) and the only “cure” is to avoid being bitten in the first place and symptomatically treat the itch with cortico-steroids and the dry sore skin with soothing creams. The fact that my gelding’s skin is better when rugged, so the bugs can’t bite him in places he can’t stop them, seems testament to that. Tail swiping only reaches so far and the more the tail is rubbed out, the less of a fly swatter it makes!

    Re the pin worms, I have read that wiping/spraying oil (olive oil is fine) around the anus and under the tail where the adult females lay their eggs stops the eggs attaching or the larvae developing. There is also anecdotal evidence that straight Neem oil or tea tree oil (diluted 2ml in 500ml of water), similarly applied also has an insecticidal affect on them. Maybe worth a try, as its cheap enough and non-toxic.

  42. I have commented on my horses’ condition in an earlier post. Just giving an update here, about 3 weeks into the treatment… I have pictures and descriptions on my Facebook page, and will try to post the link here.
    https://www.facebook.com/margo.nielsen.3/media_set?set=a.10200326885519097.1073741829.1363118263&type=1

    • Your poor horse – what misery itching causes. I see you’re on the Gulf Coast – I was yesterday reading a research abstract from the 1980s about Gulf Coast horses (Louisiana) and OC was found in around 80% of horses in breeding herds in that region. I do hope Cherokee improves. Onwards and upwards!

  43. This was well written and informative, but I still have a few questions:) Does a fecal sample reveal the presence of NTW’s? It was mentioned that a biopsy was needed. Is that the only certain way to identify them? So, the worm itself will live happily in the region of the horse you mentioned for up to 10 years and a good worming program will not kill the adult worm for UP TO that time period?? In the mean time, the adult worm will continue to produce microfilaraie and the whole process can continue for the life of the horse and all it’s herd, even through a flyless winter? Is there any research on the effectiveness of DE? Want some:)?

  44. I was just looking back at the article and the post. I posted June 22 that I discovered this article. Double doses Ivermectin right away. Treated the itch with lots of fly spay and calamine lotion to calm the itch. Just in the last couple of weeks starting to itch on the chest. No belly breakouts. I am going to do Quest in Sept. single dose. Going back and reading all the other post helps alot. Each horses are different with their reactions and symptoms. One thing for sure if you single dose and they have the worms they will itch. Thanks for mentioning NTW in the bloodstream. Read the article several times you will understand it more each read.

    • I agree, read carefully and often…….but someone mentioned I should have a fecal exam to determine if the mare is a carrier. The article mentioned biopsy not fecal check, therefore my question. IT also mentioned biopsy should be done at least 34 days after worming, therefore it created confusion in their interpretation of the life-cycle of NTW. Bloodborn/transported parasites would not be identified in a fecal exam as with heartworm in dogs, is that correct? I will read further, just wanted to know if a blood test or fecal sample would reveal the presence of NTW in the horse, or is a biopsy the ONLY way. I have resisted chemical wormers for over 5 years now. My latest rescue is the only horse I have with skin issues, and I brought her in because she was in poor condition and past owner could not care for her the way she needed to be cared for. Thanks for reply……always learning:)

      • The reason for only doing a biopsy 30+ days after worming is that you will have reduced numbers of the microfilaraie so will get a lower reading that doesn’t reflect the extent of the problem.

        These parasites aren’t blood born. They’re subcutaneous nematodes. So while like the heartworm in dogs in that they rely on a separate carrier for lifestyle stages (the culicoid fly), they don’t enter the bloodstream or digestive tract (or, of course, the heart).

        Non-chemical approaches won’t reduce onchocerca cervicalis. You can of course build your horses’ immune system so that they (possibly) have a high tolerance level and don’t develop sensitivity.

      • I didn’t worm for a long time myself, might be the reason my horse is stuck with these worms now. Everyone that double worms and the horse started to itch about 24 – 72 hrs after is a sign they have the worms. I am going to do quest this time and see what happens. It is all an experiment but my horse has a mane for the first time in 12 years. Just starting to itch some on his chest so that is why I going to do quest. It has been only 2 months since I double ivermectin.

        • mappelbee says:

          My 2yr was very badly and dangerously itchy due to NTW. When I treated for it I did Double Dose (equimax) 3x 2 weeks apart, then single dose monthly for about 3 months, now I treat him with a single dose every 2 months, too scared to leave longer. However, the last time I treated with Equest and I got absolutely no itch response at all which is very positive, makes me think that Equest is very effective (I would not do the double dosing with it though). It says on the Equest packet it lasts 14-16 weeks, do you think this also applies to NTW??? I also wonder if I’ve managed to get rid of any adults as well?

          • You will only get the big reactions to ivermectin wormers. Quest/Equest doesn’t contain ivermectin, as it’s moxidectin based, so you won’t get any itch reactions. Don’t worry, this wormer is also effective on the onchocerca microfilaraie.

            I would stick to your regular worming schedule with ivermectin, with occasional Equest worming. You will gradually bring the microfilaraie population down. Be prepared for an increased itchiness in Spring when the flies really kick in again (I see you’re in Australia).

            Nothing kills the adults except old age… :-)

  45. Ulrike Kraft says:

    Hi Jane,

    so do you recommend to single dose ivermectin every 4 weeks after the initial doubles or will only a double dose do it? And the lumps you could feel on an infected horse, can they be quite widespread (space in between) around the wither and top of the shoulders?
    I think my horse is getting better but she still has some small lumps around the wither. My friend said that her horse is better than ever at the moment but she didn’t do the worming because he scratches his tail so she doesn’t think it’s it and so I can’t say that it’s working…

    • I’m avoiding making recommendations for individual horses, Ulrike, as it’s not really my role – I’m trying to present the information clearly so that you can make an informed decision :-) I recommend the Chronicle of the Horse forum for individual suggestions.

      One thing I will say as I’ve noticed it with my own horse – the reaction to the microfilaraie, which are vectored in the saliva of the biting insects, has led to a hypersensitivity to the biting insects. It’s back there in the article. In other words, he has now developed the itch as a secondary issue, and is scratching wherever the flies bite him, ie primarily along the top line and the tail dock. My next article is going to cover this amongst other aspects of managing the problem.

      • Ulrike Kraft says:

        Thanks Jane, I’m looking forward to your next article! I will have another look at the Chronicle of the Horse forum as I didn’t really find my way around the first time I tried.

        • mappelbee says:

          Hi Jane, thanks for the info re Equest. However something you mentioned confuses me. You said Equest treats ntw larvae but does not result in the itchy reaction but then you go on to say keep treating him with ivermectin which does cause an itchy reaction………….my question is if Equest treats it (I assume kills the larvae efficiently, hence no allergen release resulting in no itch) why would I use ivermectin? Cheers Marie

          • I fear there is much to be confused about when it comes to neck threadworms… ;-)

            Research has shown that moxidectin and ivermectin are equally effective. But for some reason, Equest just doesn’t bring about the intense reaction, even when it’s the first choice of wormer used. So if people are using Equest all the time, they may not even know about the NT, because it doesn’t provide that diagnostic sign.

            Ivermectin wormers can be bought a lot more cheaply and the intense reaction appears to decrease with repeated use in most cases as larval levels decrease (anecdotal evidence). It depends on the sensitivity levels of the horse.

            I didn’t pick up that your horse is still reacting extremely when I replied – or I just wasn’t thinking straight. If you know you’re up against NT and your horse is still reacting intensely to ivermectin, then it would make sense and be more humane to use Equest. I haven’t read of people double dosing with moxidectin though.

            • mappelbee says:

              thanks again jane, ok that makes sense :). You are absolutely correct, he has only been reacting very mildly with ivermectin (post initial treatment stages) but I always worry as he seems extremely sensitive or at least very expressive…….lol. I agree, I wouldn’t double dose with Quest/Equest.either, not unless I saw proof that its ok. I made sure I double dosed with ivermectin only, nothing extra :).

  46. Hi there just wondered how common this is in the UK? I am going to call my vets tomorrow because my horse has always had a really itchy head, to the point that as soon as you are near him he just wants to rub on you. He also has lost some pigmentation on the black skin around his eyes, and has pink spots. I have been googling and have read that the pigmentation loss could be a symptom of being infected with this worm and that once the worms are killed the skin should return back to normal…. I am really hoping this could be the root of both problems and that I can get them cured!

    • Well you made me go searching… the nearest recent study apepars to be one from France, which was largely negative (although horses imported to France from Poland were found to be carriers of OM). However I found this reference, made in the 1970s, to a study done in 1910! What you might take from this is that there aren’t huge percentages of horses with the parasite, and remember that of those, many show no sensitivity, so nobody would ever know or go looking. At the very least, this gives you something to rule out. I hope the reference helps in talking to your vet. Do let us know…

      Studies on Onchocerca cervicalis Railliet and Henry 1910: I. Onchocerca cervicalis in British Horses*
      Philip S. Mellora1 p1
      a1 Department of Medical Helminthology London School of Hygiene and Tropical Medicine, London WC1E 7HT

      1. 903 horses were examined at 3 abattoirs in South East England. 10(22–7%) of the horses at the London Colney abattoir, 23(13–9%) of those at the Braintree abattoir, Essex, and 90(12–9%) of those at the Islington abattoir, London, were infected with O. cervicalis. All 105 horses examined in Southern Ireland were found to be negative.

      2. The adult worms of O. cervicalis were found without exception, in the ligamentum nuchae of infected horses. The suspensory ligaments of the fetlock and flexor tendons were always negative.

      3. The microfilariae of O. cervicalis concentrate along the abdominal mid-line of the host. In 5 complete horse hides, 95% of the microfilariae were found within 6 inches of the linea alba. The examination of 31 other horses infected with O. cervicalis confirmed this pattern of microfilarial distribution.

      4. The microfilariae were concentrated along the ventral mid-line, of the host; presumably an adaption to accommodate the habits of the vector C. nubeculosus, which bites preferentially in this area.

      5. Seasonal variations in the number of microfilariae in horse skin, as reported by Japanese workers, was not observed. Evidence was found, however, to suggest that the microfilariae migrate into the deeper levels of the dermis during the Winter. Histological examination of infected horse skin showed that the microfilariae have a very uneven distribution in the dermis. They congregate together in isolated “clumps” or “nests” and are frequently found in close proximity to the sweat glands or hair follicles.

  47. Thanks for your great coverage on this horror, I wonder if you had considered a poor on application such as Ivermectin for cattle but or for horses what would you think about that and the adult control perhaps another product chemical.Is this been covered at all?

    • Hi Stewart, as far as I’ve read, ivermectin is the main chemical used for humans and animals where Onchocerca is concerned (different types of the worm for different species) but I’ve not read about pour-on treatments. Most equine products are designed primarily for the gastrointestinal worm, but of course neck threadworm isn’t one of those.

      I have read in many places that the adult worm cannot be killed by any product.

      • Regarding the pour-on product asked about in a recent reply…
        I have a pour-on product that I purchased last year. It is for cattle, and is called Ivermectin Pour-On for Cattle, made by durvet. It is labeled for use in cattle, so use in horses would be off-label.
        It contains 5 mg ivermectin per mL.
        I wonder if that would work differently than either the injected version, or the invermectin paste wormer?
        What if the pour-on was applied right on the crest of the neck? Would it have a stronger impact on those worms?
        questions, questions… :-)

        • I wouldn’t know! I do know that injectable Dectomax, used by some vets against this parasiste in horses, is also a cattle product. Thinking off the cuff, I imagine the reason that most equine wormers are orally given is that they’re aimed primarily gastrointestinal worms. Would a pour-on product that acts transdermally be adequate for the subcutaneous worms, with less product reaching the intestines? Would the very different hides of horses and cattle make a difference, given the strength of the product? This is where you need to ask an equine vet.

  48. HI. I have also found recently that moxidectin wormers don’t seem to be as effective as Ivermectin. I will share something I have been experimenting with. I use fresh rosemary to eliminate fire ant bites. The sooner you rub rosemary on the site the faster and more completely the bite disappears. If you do not treat it with something it will very likely turn into an itchy pustule and may leave a scar. Any aromatic plant will help but rosemary is by far the best. So, I started wiping down my itching foal with a rosemary tea (1 cup boiling water and a 2 inch sprig – cool before using. Can store in refrigerator). It takes a day or two but it seems to reduce the swellings and itching significantly. I’ve started wiping down the tall infected mare with good results. I have to do this once a day. The two horses learn to love being wiped down. If ya’ll have rosemary growing, give it a try while you are going through the worming protocol.

    • I use the rosemary tea for ant bites on myself. The soothing and healing effect also seems to ease the itching and swelling of the threadworm lumps – and repels the flies somewhat. It does not CURE the threadworms – just eases the suffering.

  49. Here in Florida, my TCVM vet actually diagnosed my horse with onchocerca. She did not recommend the double dosing, but to use praziquantel on him, and again in 6 months (she said it’s not safe to administer it more frequently). My horse had the manic itching in the week following. However, after three rounds of praziquantel, I think I need to try something different because he is still itchy. To make matters worse, he’s really sensitive to bugs.

    • Donna R Simon says:

      I lived in Fl my whole life, my oldest horse Blackjack came from TN. to me when he was just under 2, with a long black beautiful mane. One year later it was itched off, gone forever. I tried everything, in the winter if it was cold it would just start to grow back then summer would come and it would start all over again. He got worst and worst and every time I would worm him he would go crazy making it even worse. This went on for 12 years. Then we moved up to NC his mane and itching around the face, chest, and belly, tail dock started to grow back. I found this article and double dosed all my horse he itched some after the worming. His mane is still growing, face belly, chest and belly are doing great. I am going to do quest next worming soon.
      Good luck

    • Worming every 6 months will make a tiny, temporary dent in the OM population in your horse. They mature within 3 weeks in the flies before being deposited back int your horse, which is why more frequent worming is usually recommended.

      If you’re using a praziquantel/ivermectin wormer, then it’s the ivermectin that’s hitting the larvae – it’s used extensively in the ‘human version’ of this problem as well. I’m convinced that in the horse, sensitivity to onchocerca milafilaraie leads to a hypersensitivity to the saliva of the culicoid flies that deliver the larvae. It has certainly happened with mine.

  50. Please contact me through the email above. I have a long history with the neck threadworm and have photos of a 28 year old mare, afflicted for over 10 years. She was finally euthanized to put her out of her misery.

  51. Ulrike Kraft says:

    Hi Jane,
    I thought I give you an update on my horses. I double drenched with ivermectin twice within two weeks and when they got itchy again after five weeks I did another double drench. I’ll definitely do it again after four weeks this time. They still have itchy areas but no blood. It’s all dry and dandruffy. Every few days I put white clay on those areas and that seems to be enough to keep them comfortable for now. I’m only wondering how they’ll go when the weather gets humid.

  52. Hi Jane
    Thank you for this extremely informative site. I thought you might be interested in my UK experience. I am in England and have a normally kind and gentle Connemara pony we purchased last winter with a few itchy spots on his neck and face. At the purchase vetting we were warned of possible sweet itch, however the seller had noticed no such signs during the previous summer. The pony did not itch all winter but started to rub his face and neck when the weather warmed up in the spring. We kept him covered with fly mask and fly rug all summer and he had a full mane and tail, but continued to rub his face and neck a little, and constantly. He had a worm count in May and it was clear so he was not wormed at that point. From July, he started rubbing and biting his legs so they often bled and were scurfy/scaly and sore. We assumed it was connected to the possible sweet itch and managed everything with topical applications all summer, but by September he was kicking out with his legs, itching all over his mane and face and really grumpy and irritable, even rubbing his tail.. He was wormed with Eqvalan at the end of August, and after reading your site, I suspect the increased mane and face itchiness coincided with that. With the continuing leg problems, we also suspected leg mites. Our vet agreed the pony had classic mites symptoms and also cannot rule out sweet itch, but told me the sores on his neck and face could be characteristic of neck threadworms. I had never heard of them. The pony was given an injection of Dectomax on 25 September and will have a second injection on 7 October. In addition, we are to consider a regular programme of ivermectin worming. His itching has become really intense since the injection and he has rubbed out areas of his mane. I started to research neck threadworms and came across this excellent site which I am forwarding to my vet to read. As you point out, there is hardly any current UK based research on this but given the movement in horses worldwide over recent decades and also the changing climate, it seems unlikely that the situation remains the same as it was in the 1910 study. Having read this site I feel fortunate to have a vet who immediately considered NTW as a possibility and I hope to discuss with him whether we can investigate the pony further and also find out if any research studies are underway in the UK at present.

    • Melanie, you are very fortunate indeed with your vet! Being open minded and recognizing that there could be more than one thing going on at a time is so valuable, especially when neck threadworms might be rarely seen as a primary cause.

      The movement of horses, yes, it’s so important to note. A non-itchy horse may be carrying neck threadworms without outward signs, then moves into a new area, where another horse nearby becomes itchy. If one horse in a paddock has it, it’s highly likely that the others will too.

      And Australia has had two warm years, including the last 12 months (hottest on record). In a sub-tropical, high rain zone, this has led to a big increase in itching – the normal winter period of relief for these poor horses never came this year. Many people sell their chronically itching horses to homes ‘out west’ or further south, in more temperate zones. It’s very sad.

      I have just posted a follow-up about managing the neck threadworm horse (or pony), covering probiotics etc…

  53. Hi,

    I have bought the liquid ivomectin that comes in a bottle, how many ml’s do I give per 100kg.

  54. Susan/ChocoMare says:

    If you want to read/wade through the biggest thread on NTWs from the Chronicle of the Horse bulletin board, here it is: http://www.chronofhorse.com/forum/showthread.php?155469-something-to-kill-adult-Onchocerca-19-CASE-STUDIES-POSTED-PAGE-58

    We do find that the Double Dose By Weight on Day 1 with Equimax (ivermectin/praziquantal) and repeat the DDBW on Day 14 seems to be more effective in those horses with long-term infestation.

    Happy reading!

    • Thanks Susan! I’ve seen it before but couldn’t find my way back to the thread, so that’s really useful.

      The only thing I’d point out to people going there for the first time is that with so many queries, inevitably there are some contributors mentioning symptoms that may not be neck threadworms. It’s just important to bear that in mind. One reason I wrote this article was to pull together a lot of the researched information in one place – this wouldn’t have been possible without the pointers offered by the COTH forum :-)

      The forum is fantastic for is suggestions about dosing – as it’s off-label and I’m not an accredited practitioner in that area, I’m not going there!

      • Susan/ChocoMare says:

        Yes, you are correct. It’s why we often posted our own “disclaimer” — If after the third double dose you don’t see Marked/Obvious improvement, then it’s possible something more nefarious is going on and you should contact your vet for consultation.

  55. Lori Maciulewicz says:

    I just read this article and it really fits the problem my poor little pony has been experiencing. He came from Alberta Canada as a 4 yr old with not the best start in life. I life in Massachusetts. He is now 13 and for the last couple of years along with some respritory problems, he bites at his legs and has been scratching his neck on every tree he comes across. This summer was particularly warm and humid and I notice little round spots along his neck and jaw. Not pustular or crusty, but very odd. I had the vet out for another horse and mentioned his extreme scratching. She brought up the possibility of neck threadworms. I had never heard of this. I did double dose him and although I didn’t see more itchiness or mood change, he did break out with bumps on his neck. I thought they were hives, but after reading this article, conclude it may be the reaction from worming him. I will double dose him again and see if he gets some relief.
    After reading how some vets have poo pooed the NTW theory, I am so glad my vet suggested it right away.

    • There are some great vets who are totally up on this! Great to hear that you might have some confirmation of the problem.

    • Sorry about the extreme lateness of this reply, Lori.

      There seems to be quite a bit of variation in how horses react to the worming, but any worsening of signs after worming, particularly with bumps, would seem to confirm neck threadworms. Never stop watching and thinking though!

  56. Sherry Moore says:

    Dear Jane,
    I so appreciate your well written, obviously well researched article. I believe my 14 yr. old Mustang is infested with the Threadworms. I worm typically once every three mos. and supplement with probiotics several times a week. I noticed a problem last year starting in the spring continuing throughout the warm weather. We had nine horses at the time and no problem with any of the others. We changed feed, increased the probiotics, tried natural allergy relief supplements, and finally Dexamethasone to give him some relief from the itching. This was a last resort as I do prefer to treat with natural supplements.
    The problem is we could only treat the symptoms not the cause. We were perplexed as to our next plan of action until fortunately finding your article.
    I believe after reading your article I could have prevented the outbreak had I continued my routine of probiotics and worming. My Mustang developed the outbreak during the year that I was recovering from neck surgery and had not been able to keep up on my routine prior to the surgery and for some time after. He flared up again this spring and is still suffering as the weather is warm during the day. I have noticed that the lumps become more prominent when his body temperature rises. Is this typical?
    I will be following your protocol for worming and probiotics tomorrow.
    Thank you for sharing ! I am so looking forward to having my good natured horse back, happy and comforable.

    • Hi Sherry, I wish you the best of luck in your efforts to help your Mustang. As the lumps are an inflammatory reaction, it seems entirely plausible that an increase in temperature would aggravate them more. I have no idea if it’s typical or not though.

    • Hi Sherry, I’m so glad to read that you’re going for the wormers. I firmly believe that the natural approaches will build the horse’s immune system and reduce symptoms accordingly, but will not successfully address the underlying issue of the parasites.

      As anyone who lives in the subtropics knows, the parasites can reach horrendous levels in the warmer seasons. So yes, I’d expect to see increased inflammation and bumps during these times. The adults can’t be killed and will be shedding more larvae, which the flies – also present in higher numbers due to the season – will transfer more of them.

      So I agree with you that a protocol involving ivermectin, the probiotics for the immune system, and topical applications for the irritation and lesions is a a great idea!

  57. Ken Morgan says:

    Thank you, thank you, thank you Jane@THB, and a special thanks also to mappelbee.I have also spent a fortune on treating ‘Qld Itch’ with limited success. I’d been told the cause was anything from high blood sugar to sensitivity to humid climates. My intended question to you was ‘ why is it then that once I ship my ‘itchy’ horse to a non humid area, the condition is resolved’, but mappelbee answered that for me.. Thanks again for sharing this priceless piece of information

  58. Margo Nielsen says:

    UPDATE on my horses with this problem…

    On Aug. 5th I started them on an herbal Sweet Itch mix (from HerbNHorse.com) a few days before I started the double dose of Ivermectin 3 weeks in a row. I was hoping to minimize the itching, bad as it was, which might get worse from the Ivermectin. The first month it seemed that they barely stopped itching. Then they got a single dose of Ivermectin each month since then, and will get it monthly for the rest of their lives. They are aged and may die before the Threadworms do. The second month they seemed to be itching a lot, but their skin was actually healing. I’m afraid to stop the Sweet Itch herb, so I won’t. It has no negative side effects and they seem to love it in their wet beet pulp at the midnight feeding.

    Now it is 4 months later and their coats have grown back in all the previously raw areas. The manes and tail are going to take some additional time. I have only photographed the pinto horse, Cherokee, because my black aged TWH gelding just doesn’t show up in photos.

    The Sweet Itch blend consists of equal parts of chamomile (soothing, calming), burdock (anti-inflammatory), garlic (bug repellent) and rosemary (also a bug repellent). The two links below will take you to my Facebook post on his condition at its worst and then follow up photos.
    My Facebook posts are public, so anyone should be able to view them. Thanks!

    https://www.facebook.com/margo.nielsen.3/media_set?set=a.10200326885519097.1073741829.1363118263&type=3

    https://www.facebook.com/photo.php?fbid=10201007668978258&set=pb.1363118263.-2207520000.1386217668.&type=3&theater

    • Margo, thank you so much! I will certainly be sharing your pictures on my Balanced Horse facebook page. Hopefully your story will help to inspire others that it’s never too late to help an older horse with itch problems. I have to say, your photos make difficult viewing – it must have been such a hard journey for you over the years.

      • Margo Nielsen says:

        Jane, Sorry about the photo quality. I don’t know how to set the resolution on my phone camera, if it’s even possible. The horses have only had the problem since August 2012. I believe they had such a severe reaction because of their age. Cherokee is showing signs of Cushings.

  59. 27 yr mare has signs of this 2 years now, vet said culicoides allergy, used Dex IV, IM and orally
    can the Injectable Ivermectin (for bovines) be used IM on horses? I use this liquid orally for horses.
    What about the “pour on” also used on bovines… can it be used externally right along the mane area?
    apple cider vinegar, raw organic, supposed to help w pH, provide pro-biotics, soothe and remedy skin eruptions

  60. Judy Streiber says:

    I havent read all the threads yet, but thank you for this very informative article.
    I rescued a young horse totally covered on his entie body. I found that using lice
    Shampoo helped immensely in reducing the symptons and controlling
    The larvea stages. Definitely had to address the overall health and immune issues
    As well. But it was alot better and easier to do with using the lice shampoo too.

  61. Jane I’m not sure if you have posted this link elsewhere in the articles and I’ve missed them, but this is the page 1 link to the Chronicle of the Horse thread on their forum with case studies etc., now added. It is now up to 81 pages long. I’ve followed this thread since about 2009 and even though it is incredibly long – it is a worthwhile read.

    http://www.chronofhorse.com/forum/showthread.php?155469-something-to-kill-adult-Onchocerca-19-CASE-STUDIES-POSTED-PAGE-58&highlight=Onchocercca

    On another note, have you had any experiences or know of any success with using Ivermectin and DMSO along midline/neck and tail head? It is mentioned in the thread above and apparently helps with the intense itching in those areas by targeting microfilariae. My hesitation is that DMSO crosses the blood/brain barrier?

    Thanks – and keep up the good work.

    ~Kerry.

    • Margo Nielsen says:

      Kerry, Thanks so much for doing the footwork in finding the info in the Chronicle forum. It really is a daunting chore. I am forwarding a link to p.58 to another group which is discussing this because of their tormented horses. I went through this last year and it is very hard to convince people when their vet says there is no NT in their area, contrary to the evidence. The value of this particular link is the mention of being able to test for it.

      • Thanks – I mention the COTH forum quite often in the replies to comments, but I can quite understand if people don’t read every single one, so another mention is more than welcome!

    • Hi again Kerry

      I decided it was time to find the answer to the pour-on ivermectin for cattle question – is it safe for horses? So I asked a senior scientist vet, who explained it well. I’ll paraphrase here.

      As you say, DMSO (Dimethyl Sulfoxide) is a detergent/solvent product that enables the pour-on ivermectin to penetrate the skin to the subcutaneous layer. It’s surprising to read that this product is at once advocated as an alternative treatment in human medicine, while being subject to campaigns against it, due to its toxicity.

      When using a pour-on product such as this, designed for cattle, on horses, it’s obviously important to note that the skin of the two species is significantly different. It’s probably safe to assume that a higher dosage is required for cattle than horses.

      Another difficulty is that different species, or even breeds within species, react to ivermectin in different ways. A normal dose of ivermectin can cause some individual to throw a fit – apparently rough-coated collies have a genetic mutation that renders them sensitive to the drug in this way.

      Vets make a decision to use products off-label based on research papers – and on the recommendations of other vets. Technically, they should advise us of the very small or miniscule risk involved in drug use, especially if it’s off label – but obviously, this doesn’t happen and (possibly) the majority of owners wouldn’t expect to receive the equivalent of the small print leaflet in the aspirin box every time their horse receives a relatively innocuous treatment. (BUT I’m sure that the owner of dogs who have reacted negatively to pour-on treatments would feel otherwise.)

      Throwing a fit is a serious reaction and could be life threatening. It could very well be that using a pour-on product will never deliver enough DMSO to penetrate the system to that degree. However, if it’s an animal that is sensitive to ivermectin… I saw a sheep drop with it last week and it was a startlingly fast reaction.

      HOWEVER orally administered treatments are a lot safer (I am told by this animal scientist) because a very wide margin of error is involved with the dosages, and a significant amount of the drug passes through the system anyway.

      I have also read a research paper concerning a study in which pregnant mares receiving a periodic overdose of ivermectin, 3x that on the packet, suffered no adverse affects – nor did their foals. (Oddly enough, the only foals that experienced problems were those in the control group, which received no ivermectin at all).

      So, as with many treatments we give our horses, it comes back to making an informed decision – whether to use, and if so in what dosage, or whether to play safe and not use. There’s often a reason such treatments aren’t licensed for horses and the fact that 99.9% of them will be fine is of little comfort to the owner of the one horse that pays a big price.

      Hope that helps – I certainly found it an interesting conversation!

  62. By the way, after a horrible outbreak last year on 2 of my 4 horses …. I also read in my research that humans CAN contract neck thread worms from their horses as well.

    Ick.

  63. I have a 9 yr old paint gelding that I have noticed some small lumps under his thoatlatch and on his cheeks. They are crusty and sometimes oose. The lumps seem to hurt if you try to squeeze them like a pimple. I board him at a small barn and my job keeps me away during the week. I worked him the end of November (I know that’s way to long ago) so I’m not sure of how itchy he is. Could this be neck treadworms?

    • Hi Angela, I’m sorry, I’ve only just seen this post. There are many things this could be… I’d recommend observing his responses after worming with ivermectin as an early indicator of neck threadworms. Also, the Chronicle of the Horse forum mentioned a few posts above this one is worth checking in with – a lot of people post photos there. Best of luck!

  64. Anita Thompson says:

    This has me captivated, interested and intrigued!!!! Someone posted a link on Facebook months ago about Neck Thread Worms…..i had a brief look and that was it!!! I can soooo relate to everyone’s comments (except my fella hasn’t started on his underbelly …… yet)!! It was mentioned earlier about “wavy skin”….. would that kind of be like it looking crinkly and a little de-hydrated? I’m just trying to visualise what it looks like. I asked my vet to do a skin scraping to check for mites……I was told it’s probably not mites and wash him in medicated shampoo that’s a fungicide …etc….etc…..sound familiar???? I’ll definitely be following everyone’s comments…….and definitely off to get my ivermectin tomorrow :) Thank you so much everybody for your input and insight…..and Jane, thank you for the comfort you’ve given so many horses (and their owners) :)

    • Anita, The waves were located about where the neck thread worm lives along the crest of my horses neck. They showed up on the third day of a 5 day Panacur powerpak and I had never seen anything like this and I have been in the horse business for 40 years. I researched this and found the Neck thread worm protocol and started that the next day. Its been two years, and no more itchy horse or any more signs that the microfilia is still there in amounts that bother my horse. I do the protocol at least once a year.

      • Anita Thompson says:

        Thanks Rachelle, i understand that, i was trying to get an idea of what the “wavy skin” looks like :)

  65. Can i just ask if anyone’s horses developed a hyper-sensitivity to this certain type of fly?? My fella can have the normal black flies sitting on his face but then all of a sudden the “no-see-ums” come along and he’ll start tossing his head to get them away from him, or drop his head like he’s hiding from them. I’m starting to get a little concerned at this behaviour….. could it be related do you think? Thx

    • Donna Simon says:

      When I in Fl we had terrible no see ums. I thought that was his issue for his tichy problem. It might have had something to do with it but I truly believe it was the NTW’s. I would fly spray, fans, keep him in at dusk and dawn, garlic, I tried it all. It did help leaving him in but then he would scratch in the stall too. Once we moved out of Fl to NC he was much better for sure and now that I have double wormed him last year and once this year so far he hasn’t scratched off his mane for a year.

      • Thanks Donna! I did the double dose on Saturday afternoon, today is Monday, i will dd in 2 weeks. I don’t know if he has NTW but this itchy behaviour and the head tossing is driving me (and him) nutso!!! I was just wondering if this symptom (the sensitivity) was part of the whole picture?? I’ve tried all the sprays, creams, additives in feed etc etc all to no avail :(

    • Margo Nielsen says:

      Yes, Anita… the same with my horses… no real problem with flies, but when the gnats start buzzing around they go crazy.

      • Thanks Margo…..i was starting to feel like my horse was becoming a neurotic mess (and me too)!! Will see how he goes after the dd i gave him on saturday and the next one in 2 weeks!!

        • Margo Nielsen says:

          Anita, Don’t be alarmed if he starts scratching madly a few days after the dd. It is a sign that it is working! At the end of the the triple use of double doses, it will have been a month since beginning the treatment… then all of a sudden he will be calm and his old self and you will notice a lot of healing where he had been scratching.

          Rachelle, I have noticed that when the horses’ immune systems are so stressed, they react to all kinds of stimuli in a negative way. Resistance to fungus is lowered. My 30 something gelding used to get rain rot on his rump even if there were just a few drops of rain, so he always sought cover in rain. I have also noticed that I have to clean my geldings’ sheaths frequently since they have this problem (the last year and a half), and I never had to do it before.

      • Rachelle says:

        Have you ever seen this same weird behavior when it starts to rain or drizzle. Besides going nuts with the no see-ums, my horse goes nuts when it rains or even just sprinkles. Hard rain does not bother him. He is now due for his next double dose. I usually have to put everything but the kitchen sink on him just to turn him out for an hour. As soon as the swarming of the no see um stops, he seems to get better but the hyper sensitivity to the rain never goes away.

    • Hi Anita, I’ve written in the second article “How to Fight the Big Fight…” that I believe a hypersensitivity caused by the microfilariae can lead to a reaction against the saliva of the same culicoides that deposit the Mf in their saliva. My horse had never had the itch and then suddenly acquired aged 5 years, after I’d identified the neck threadworms.

      • Thank you Jane, i’ll have to go back and re-read that article. I think i got so excited to think that i may have found a solution (or what the problem might be) i was speed reading and not taking it in properly!

        • I can’t remember everything I’ve written here, so I hardly expect anyone else to! I’m just very pleased that other people are finding a way through this problem. Good luck :-)

          • Thank you Jane, will keep you all posted. Just a little update…..he’s given his mane a little work out (scratching) and still tossing those midges with his head – can’t wait to dd him in another weeks time!

  66. I have a shire mare that I bought as a welfare case about 4 years ago and her neck rubbing drives both her and me mad! She’s had her fair share of problems in her earlier life (she’s now 8) most of which we’ve overcome, but I still can’t get on top of this rubbing and am now seriously beginning to thing it’s NTW.
    We’re in England though, not renowned for our hot weather, although certainly have our fair share of midges. Do you have any recorded ‘sightings’ of the things over here?

    • Hi Deb

      Somebody from the UK had a vet assess their horse as having NTW – it’s somewhere up there in the comments. And one of the oldest bits of research that I’ve read was from the Home Counties in the early 1900s. More recent research comes out of France and Poland, so I don’t believe the north European climate precludes NTW.

      I’d imagine that the increase in worming practice will have severely knocked them back since the 1960s, so no doubt the incidence is way lower than in the hotter climates. However, as you say your mare was a welfare case, who has likely been around other ‘underwormed’ horses, it certainly seems worth eliminating. A couple of tubes of ivermectin wormer could give you an answer – look for the frenzied itching during the following week (it’s hard to miss it!).

      Please do let us know how you get on… it’s all useful information to pass on to other people.

      • Deb Eastwood says:

        Thanks for your reply Jane. Have worked out her weight as accurately as possible today and intend to double dose her tomorrow. Will keep you updated re results. I’m giving her a liver booster supplement for the next couple of weeks as well as I don’t like over worming and am very cautious re double dosing but feel I have to give it a go.

      • Deb Eastwood says:

        Hi Jane,

        Sorry for taking so long to reply, I’d lost this thread and have only just found it again.

        I do think the neck threadworms are at the bottom of Lily’s problems. She was about 5 days before she began itching, to the point that I’d begun to think I was wrong.

        Unfortunately she was away at stud when she began, and came back with less than half the mane she’d gone with and a neck full of sores so I’m pretty sure this was the cause.

        I’m in a bit of a dilemma now, as ordinarily I would get straight in and double dose her again, but as it seems she may be in foal (has been back to stud and was adamant she wanted nothing to do with the stallion – just waiting for a scan now) I’m reluctant to do anything that could upset the embryo, despite the literature with the Ivermectin saying it can be fed to mares in all stages of pregnancy and lactation.

        Any suggestions would be gratefully accepted.

        Regards,,
        Deb.

  67. Joyce Robinson says:

    I have been treating my mare for 3 years for Sweet Itch. No help at all from my vet who basically said that I needed to give her decadron, up to 5mg IM – up to 3 x a week to help with the itching. I’ve tried everything. Even the steroids don’t seem to help the itching. I get no answer from the vet, but am going to double dose her today with Equimax, then 1 week another double dose, then 1 week later a single dose and see what happens. Thank you so much for this article and thread. I’ll let ya know how it goes.

  68. Deb Eastwood says:

    Hi,

    I last posted on here on 27th May re my mare. .

    Almost certain she has NTW as she has virtually no mane left now following Ivermectin double dosing.

    I’m happy to write the mane off this year and get to the bottom of the worms but she is definitely in foal so I’m concerned that the double dosing may have an adverse effect on the foal despite what it says on the leaflet.

    Anybody any ideas?

    • It’s good to hear that you’re making progress, even though it’s at the cost of her mane :-( The price of comfort, eh?

      I’ve read a good research paper that covers a test done on pregnant mares. Two groups were given different high levels of ivermectin wormer – up to 5x the recommended dosage and 3x during the pregnancy – while the control group was given nothing at all.

      No adverse affects were reported in the foals, with minor issues being within the normal range. One foal died and it was in the control group, so the dam in that case had received no wormer at all.

      I’d give more details but I don’t have the paper here in front of me.

  69. Heather Hamel says:

    Thank you for this information. I’ve been treating my mustang for years for sweet itch and nothing has worked – that’s because I’ve been treating the wrong thing! I feel as if the end of the itchiness may be in sight – we have hope again!

  70. Anyone know if we have Neck Threadworms in New Zealand?
    Reason for asking is that last summer and the summer before that, my horse had incredibly severe itching. Awful. Started when I was grazing in a place where there were lots of sandflies – New Zealand blackfly (Austrosimulium australense). I moved grazing, but the itching was even more intense last year. He was on steroids, bathed daily with iodine washes etc.
    I also tried dietary things – linseed etc. Plus stopped using synthetic rugs against his skin. Many many things I tried. The itching finally went away, probably when the colder weather hit. It hasn’t yet returned and I hope it never does.
    However, since then, he has had problems with his eyes. Since he fell on his head 12 years ago, he has always had one dribbly eye – often squinting in the sun with it. But since the itch stopped he has had trouble with both eyes and it got worse and developed into Uveitis. Went through all the normal treatment with steroids etc. No real progress until I got a Guardian Face Mask a few months ago and as long as he has it on, he’s fine, but minutes after taking the mask off he’d be squinting in pain again. For a couple of months now, I’ve been giving him Turmeric, oil and freshly ground black pepper and his eyes have improved dramatically. I’m very hopeful for the future.
    I’ve been researching Uveitis for months now, and found that NTW may be responsible for Uveitis/eye problems. So I’ve ordered Equest wormer and will let you know what happens.

    • Hi, it sounds like you’re having a really difficult time there. The ‘human’ onchocerciasis causes ‘river blindness’ due to its effect on the eyes. I’ll be interested to hear how you get on. Are you still discussing this with your vet?

      • Jane – after thousands of dollars spent on vets and drugs over the past two years for his itch and then his eyes – none of which helped much, I’ve just been doing stuff myself – researching and trying out. And his eyes are MUCH better since I’ve been doing that – one eye actually seems perfectly fine now – woot! And no itch at all. The other eye is still a bit squinty when he’s not wearing his mask, but it isn’t too bad and seems to be improving all the time (fingers crossed), as long as I keep up the turmeric, pepper and oil. If I miss a few days of feeding it, his eye seems to go downhill again. And I’m too afraid now to take the Guardian Mask off – that thing was magic for his comfort.

        I DO have a vet friend that I catch up with every couple of months on what I’m doing. She’s extraordinarily clever and it’s a bit like talking to an encyclopaedia. She and her husband have a big free-range pig farm so she is pretty up on everything. She was fascinated with the Turmeric I’m trying, and came out with about 10 minutes of rhetoric on why it WOULD be working lol (mainly around inflammation). I am so far, very impressed with what the Turmeric appears to be doing. I just wish I’d known about it when the poor bugga was suffering so much with the itch.

        Just in case anyone reading this wants to try it for the itch, you need to do some homework first. The stuff from the supermarket etc is no good – it’s usually had the active ingredient – cucurmin – removed. Plus it needs oil to work and pipperine from freshly ground pepper. If you try it without these things you’ll be disappointed. I joined a Facebook group started by an Australian vet – lots of info there on how to use for Turmeric for sarcoids, itch, arthritis etc.

        After finding this article, I am looking forward to worming my boy with the Equest first (it’s on order), then with Ivermectin maybe a couple of weeks later? He hasn’t been wormed for a couple of years as his samples always come back ok, but I’ve always been worried about encysted strongyles. And now, perhaps, NTW. This article has been a great learning tool for me and I figure I’ve got nothing to lose and you never know….. THANKYOU.

  71. Kerry Belot says:

    Hi Jane, I too have a mare that has come down from Qld and started to itch last year. I have been treating her with ivermectin and only having a small effect. The vet said she had dermatitis, took a skin scraping to confirm it charged me heaps. The Vet also said to give her minerals everyday so following the Pat Coleby idea I have done so. Dolomite, Seaweed meal, Sulphur and a pinch of Copper Sulphate. Interestingly enough, the itching episodes have subsided somewhat. Wether it is working or coincidence I am not sure but she seems less distressed.

    Cheers

  72. I have been fighting with my horse’s itching that has gotten worse over the past 6 months. We live on the coast of SC where the gnats are horrendous! He wouldn’t allow you to even rest the reins on his neck it was so bad. I believe he does have Threadworms and plan to do the DD of Ivermectin Nov 1 to see it that helps. I feel so bad, have tried so many things, keep him in under fans and completely covered when in the pasture and nothing seems to have helped so far. I even roached his beautiful blonde mane (he’s a Haflinger) because he seemed so miserable and he has rubbed his tail to half the size it was. I have searched and searched and now I might have found the reason – THANK YOU.

    • Kerry Belot says:

      Ivermectin is helping my mare as are the minerals, have also started her on turmeric as per the Turmeric User Group on facebook. Poor thing has rubbed her chest again, It seems to be a never ending battle.

  73. Donna Simon says:

    Just wormed my horse this morning with double ivermectin wish me luck. Last season only had to do it once for him to get relief. He was going after his main this week. I am so happy for this article as it has saved my horses main tail, face, belly, and under his front legs.He would rub himself raw in the summer. Fly spray, creams, fly mask, fans, and leaving him in the stall were he would itch like crazy after I wormed him. Nothing worked, till I read this article, thanks again Jane.

  74. Just to be clear, you did double dose by weight and just the single double dose worming will not do it. You need to come back in 2 weeks and do it again and then 2 weeks after that. The reason for coming back is to make sure that the microfilia do not build up and that can be safely excreted out of the horses body and they do not turn into adult neck threadworms that you can not get rid of.

  75. Donna Simon says:

    Yes I did. He has not any issues as of yet with this worming.

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