How to Fight the Big Fight against Neck Threadworms


This follow-up to ‘The Disturbing Truth About Neck Threadworms and your Itchy Horse’ discusses how to manage the parasites, once you know your horse has them.

The original article was aimed at my Australian bodywork clients here in NSW, yet it quickly worked its way through other networks – I haven’t a clue what or where, but it started running and it’s still running today.

Astonishingly, it’s now been read by over 28,000 people in 90 countries – and that’s in the first four months.

I make no claim to be the first to write about neck threadworms. For making it a more widely known issue, the forum members of The Chronicle of the Horse website must take credit (and I recommend anyone with specific questions about their horse to head over there). I guess my post succeeded in bringing the available information together in one place – in that it simply reflected my own experience of researching the subject on behalf of my newly itchy, increasingly unhappy horse.

‘The Disturbing Truth’ has certainly offered a possible answer to many owners whose horses are besieged by the living hell that is variously known as Sweet Itch, Summer Itch, or Queensland Itch. That’s because in a certain percentage of cases – not in all of them – the cause is onchercerciasis, a hypersensitive reaction to the larvae of the Onchercerca cervicalis parasite.

Ignore the nay-sayers – it’s an international battle

Imagine your itchy horse with a regrown mane...

Imagine your itchy horse with a regrown mane…

One thing that’s become really, really clear from responses to the first article is that onchercerciasis is a problem for horses worldwide. It’s obviously worse in some climatic areas than others, but that doesn’t mean it doesn’t exist in cooler zones.

Reading the comments triggered by the article tells us all we need to know. Horses travel within countries and internationally – the larvae can then be transmitted to new host horses in the destination region, providing there are enough local culicoid flies to transmit them. As another reader pointed out, warmer and wetter winter and summers are giving the flies a better hit at it than ever before.

Research has shown the presence of neck threadworms in horses in such non-tropical countries as Canada, the UK and Poland. In fact, the UK research was conducted in the early 1900s, showing that air transport of horses has little to do with it and that this parasite has been in cooler climes for a long time.


Dragging neck threadworms into the daylight

The comments at the bottom of ‘The Disturbing Truth’ are illuminating. Some people have battled their horses’ itch, often so bad that it prevents their horses from being ridden, for a decade or more. They have struggled with different diagnoses, with various medications, with investigations into suspected colon disorders and testing for allergen sensitivities, all to no avail. Everyone involved certainly meant well, but the problem still remained.

Astonishingly, more than one person has previously mentioned neck threadworms to their vet, only to have it dismissed out of hand, because “that’s not a problem around here”.

Despite this, some of those same horse owners have started treating their horses and are already some way down the road to reducing the larval population and are resolving the issue. Some are seeing manes grow back on their horses for the first time in years.

This isn’t to say that all itching is caused by the larval stages of Onchocerca cervicalis. I don’t want to be grandiose about this. But it’s certainly affecting enough horses for it to be worth ruling out. For the price of a couple of tubes of ivermectin wormer, why on earth not do just that?

Culicoid fly in close-up

Culicoid fly in close-up

It’s baffling that this problem has ceased being common knowledge and so often slips under the radar. It’s true that the companies producing wormers certainly know about neck threadworms, but quite naturally focus on promoting their products’ effectiveness against far more serious gastrointestinal worms. (And let’s be honest, many horse owners feel distrust towards drugs companies, whether involved in human or veterinary medicine.)

Even so, in regions such as the Australian tropical and subtropical zones, you’d think there’d be a bit more awareness, wouldn’t you? But then perhaps we’ve all been so hung up on Queensland Itch, we’ve been unable to see the wood for the gumtrees.


Down to business: How to win at worming

With your initial burst of worming, either on a fortnightly or monthly basis, single or double dose (as described in ‘The Disturbing Truth’), you’ll have established that your horse does indeed have neck threadworms. Using ivermectin, you’ll have seen a temporary worsening of the problem and, possibly, the increased itching and/or eruption of pus-filled lumps in the mane.

Moving on from that point , it’s important that you establish a strategy for dealing with the ongoing presence of the neck threadworms in future months and years.

Regretfully, when I say ‘win at worming’, what I actually mean is ‘win at managing the worms’. As we know, you can’t kill off the adults, only the microfilariae. Hence you can only strive to bring it all under control.

That’s why tackling neck threadworms in your horse is a numbers game. It’s safe to assume that most horses can deal with a relatively small number of microfilariae, so it follows that the more you can bring those numbers down – and keep them down – the more likely it is that your horse will be able to deal them without experiencing hypersensitivity.

In other words, the itching will ease.

A calcified lump in a dissected nuchal ligament

A calcified lump in a dissected nuchal ligament

Just to repeat: you can’t bump off the adults. Once they’re in your horse’s nuchal ligament, they’re there to stay for 10 years or more. And then even when they die, they remain present, entombed in a small calcified lump in the ligament. You can see one in the picture on the right. ‘M’ marks the center of a lump nearly 2x4cm in a veteran horse’s nuchal ligament.


How frequently should you worm?

At different times of the year, the microfilariae being introduced to your horse will vary in numbers, depending on the level of culicoid flies around. This means that with evenly spaced wormings, you’re going to have different results at different times.

As the warmer months are going to see faster increases of the population, it makes sense to worm more frequently in Spring and Summer. The microfilariae are picked up from a horse by the biting fly, after which they develop in the fly for 15-21 days (research seems to differ on this point). The flies are the vectors that take the larvae through an additional life stage. After this time period has lapsed, they deposit them back into a horse. This is going to happen faster with horses that live in herds within a kilometer or so of standing water.

  • Some owners feel that monthly worming during Spring and Summer is sufficient to interrupt the pre-adult lifecycle. Check with your equine vet if you’re not sure (although one reader’s vet suggested worming at 6-monthly intervals, for some mysterious reason).
  • Once the microfilariae numbers are down, possibly after the first year, some owners come down to 6-weekly and 8-weekly wormings.
  • Others prefer to leave the horse from mid-Autumn until mid-Spring, following only a ‘normal’ worming schedule during this time, before worming more frequently during the fly season.

In the end, it’s a matter of individual choice. All you can do is observe your horse and keep at it until you see a significantly reduced reaction in terms of itching.

The longer your horse has been living with neck threadworms, the longer it’s likely to take. And the more tropical and humid your regional climate, the more biting flies there are going to be. Even so, you might be pleasantly surprised by the speed of the positive change.


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Include gastrointestinal worming in your plan

Once you’ve used an ivermectin wormer to identify the presence of neck threadworms in your horse (see ‘The Disturbing Truth‘), it’s sensible to also worm intermittently with moxidectin, found in Quest/Equest. The reason is that this is the only wormer to hit Onchocerca microfilariae AND encysted small strongyles.

Encysted small strongyles in the colon. (c)

Encysted small strongyles in the colon. (c)

While neck threadworms can make life highly unpleasant for your horse, encysted small strongyles can kill him or her if they suddenly erupt. They would have to build up to a high level first, but if your horse has been malnourished before coming to you, or is a rescue horse, or if you’ve only used ‘natural’ wormers for some years, you have the perfect conditions for such an event.

The best approach is to address the intestinal worms before moving onto the neck threadworms. So if it’s unlikely your horse has had Quest/Equest or Panacur for some years, use one of these first.

In my region, Strategy is also valuable in addressing pinworms, which are resistant to many other products.


Support your horse’s intestinal tract

Shop for the Best Discounted Pet, Equine, & Livestock Supplies!Worming for neck threadworms is always going to be a necessary evil. None of us would wish to be following such a rigorous worming schedule if we had the option, so we must do our best to mitigate any negative effects.

If you’re following a heavy worming schedule, you should also be supporting your horse’s gut, which is going to be taking a chemical hammering.

The best place to start is with probiotics, either added to the feed or administered through a plunger tube (although your horse may be a little off plungers at the moment…). The reason for using a probiotic, which is essentially a supply of beneficial flora for the hind gut, is that the existing ‘beneficial bacteria’ will have been reduced by the wormer. It’s then more likely that pathogens (‘bad bacteria’) will proliferate, potentially leading to intestinal inflammation and diarrhoea. This is not only uncomfortable and painful for your horse, but the affected digestive processes will reduce nutritional uptake, which in turn leads to an impaired immune system.

And what happens with an impaired immune system? The horse will be itchier.

Using probiotics means that in supporting your horse’s intestinal function during worming, you will also be supporting your horse’s immune system. It’s a double-win .

You can also help to restore damaged mucosal lining. Various plant sources are ‘mucilages’, meaning that when mixed with water, they form a slippery substance that lines and soothes the intestine. You can consider using aloe vera juice, slippery elm, marshmallow root, liquorice root and chia seeds.


Itching elsewhere on the body

Some owners are saying that their horses, which have had all the signs of neck threadworms, have also started itching on the tail head and along the back. This doesn’t fit with the usual oOnchocerciasis locations of head, neck, chest and ventral areas, and could be due to:

  • Pinworms, which lay eggs around the anus and cause itching of the tail head,
  • The horse reacting to dying microfilariae previously delivered by culicoid flies biting in ‘atypical’ areas of the body (it’s interesting to note that bite locations may vary according to the particular species of fly, which differ from country to country),
  • The horse reacting to the saliva of all culicoid flies, having become hypersensitive to microfilariae that have entered their current life stage within the flies’ saliva. In other words, the horse has developed the Itch.

It’s worth noting that there are two different types of Onchocerca worms also affecting horses and donkeys, and that these cause problems in other areas of the body.

  • Itching on the legs can be due to Onchocerca reticulata, as the adult worms are found in the connective tissue of the flexor tendons and suspensory ligament of the fetlock, mostly in the forelimbs.
  • In donkeys, Onchocerca raillieti are also found in the nuchal ligament but also, nastily, in subcutaneous cysts on the penis and in the perimuscular connective tissue. 


Can neck threadworms lead to the dreaded ‘Itch’?

Itching along the topline

Itching along the topline

Now, this is where things get a bit curly. Once your horse has started reacting to Onchocerca microfilariae, they may develop The Itch – aka Queensland, Summer or Sweet Itch (take your pick). If their system is reacting to the microscopic larvae carried in saliva, why not react to the saliva itself? The immune system is nothing if not intelligent: it learns and it acts on the information it receives.

I’ll be honest here. I’ve not read any research into this, but hooray for Dr Carl Eden BVM&S MRCVS of Virbac, who writes:


Internal parasites such as Onchocerca cervicalis… may also cause pruritus and in the case of O. cervicalis, its involvement in cases of Queensland itch must not be underestimated.

Let’s look at this for a moment.

The Itch is a clinical syndrome, being a hypersensitivity to certain allergens. When the allergen is the saliva of the culicoid flies, the outcome is an inflammatory response. This in turn leads to a pruritic (itching) skin condition. We’ve all seen its awful progression from hair loss, bumps and wheals, to alopecia, crusting, broken skin and worse.

So I’m speculating here: some of the horses with neck threadworm symptoms develop the Itch as they develop a heightening, acute sensitivity.

The thing is, whether this supposition is right or wrong, you can do no wrong by managing your horse as if it has both neck threadworms and the Itch.


Managing the itching side of neck threadworms

Furiously rubbing the tail head leads to hair loss (c)

Furiously rubbing the tail head leads to hair loss (c)

While you’re working on reducing the microfilariae numbers, there’s plenty you can do to make your horse more comfortable. There’s nothing worse than seeing your horse breaking his or her skin while rubbing an itch that won’t ease, whether it’s caused by neck threadworms alone, by the parasite and a developing itch problem, or by the parasite and a pre-existing itch problem.

I’m not going to go into lots of detail as to what you can do, but here, in no particular order, is a starter list.

  • At the heavier end, a short course of glucocorticoid therapy (ie, steroids) will reduce the inflammatory response. Some owners have used oral prednisolone – Preddy®-granules –  to support their horses during the initial stages of ivermectin worming. It’s not good for pregnant mares, suspected or actual laminitics (steroids can trigger an onset) and horses with internal issues.
  • Antihistamine preparations work on the chemical response, but may lead to occasional behavioral changes or even have a sedative effect.

There are changes you can make to your horses diet and nutrition:

  • Supplementing your horse’s diet with Essential Fatty Acid (EFA) – Omega 3s – has been shown to reduce insect hypersensitivity. This can be a shop-bought product, or cold pressed linseed oil, or cod liver oil added to the feed.
  • Improving mineral supplementation helps to boost the immune system. This doesn’t mean using an off-the-shelf standard product, although that is better than none. Ideally, identify the deficiencies or imbalances in your horse’s forage and diet, and then supplement accordingly.
  • Some people are using a combination of chondroitin sulphate, spirulina, and ground linseed (flax) in the daily diet, with some success.
  • Probiotics also help to boost the immune system by improving gut function, as we saw earlier.

There are also measures you can take to keep the culicoid flies away from your horse in the first place:

  • A fly rug keeps the carriers, the culicoid flies, away from the horse (c) sweetitchtreatments blog

    A fly rug keeps the carriers, the culicoid flies, away from the horse (c) sweetitchtreatments blog

    External and topical protection can help to keep the culicoid flies at bay: fly rugs, wipe-on insecticides, and oil-based creams and lotions, especially those containing camphor, menthol or thymol, act as barriers while providing relief and repelling flies.

  • If you stable your horse, try to do so between 4pm and 8am, when the biting flies are most active in subtropical and tropical zones. Fans will help circulate air and discourage flies, while mosquito netting on windows will also help.
  • Bathing in dermatological shampoos containing chlorhexidine gluconate bring relief while working against localized bacterial infection.


Do it your way: it’s an individual fight

Ultimately, the line you take when tackling neck threadworms in your horse is going to be an individual one. You’ll be taking into account the severity of your horse’s reaction to the microfilariae, the duration of the problem, and the intensity of the fly presence in your area. And in managing the itching side, different treatments will work with different horses.

Let’s not forget, there’s also the matter for what you can do in practical terms – eg, if you’re never home from work before 6pm, you’ll be unable to stable your horse from 4pm every day. And then there’s what you can afford to do on a financial level, especially if you have multiple horses affected (one reader of ‘The Disturbing Truth’ had four).

fight-header-2Please feel free to add your comments and share experiences below. We’re all learning and the contributions are fantastic. Meanwhile, if you’re after specific advice for your individual horse, I recommend talking to the guys over at the Chronicle of the Horse forum.


Queensland Itch, Dr Carl Eden BVM&S MRCVS

Studies on Onchocerca cervicalis Railliet and Henry 1910: I. Onchocerca cervicalis in British Horses* Philip S. Mellora1 p1 , J Helminthol. 1973;47(1):97-110.

Prevalence of Onchocerca cervicalis in equids in the Gulf Coast region. Klei TR, Torbert B, Chapman MR, Foil L.  1984 Aug;45(8):1646-7.


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  1. I’ve been following the worming protocol for neck threadworm more enthusiastically this season on my itchy mare. So far the results are very positive and she still has a full mane and tail and very little scratching and itch. If by the end of summer I’ve managed to maintain the ‘itch free’ state, I’ll be extremely happy as will my horse. Thanks to the information I found from this site and Chronicle of the Horse 🙂

    • I’m fighting this right now. My horse started scratching 3 years ago. I came across the article the COTH article from another site. What a nightmare! I have him at a point where he is a lot better, but I’m finding apparently not good enough as I’m having to worm him every 2 weeks before he starts scratching again. These are what I call the worm’s from hell. Has anyone tried the heart worm treatment? I’m at a point where I’ll try anything. And why is it that there appears to be nothing to treat the adults? I didn’t have to de-worm in the winter due to living in a very cold climate and the worms going dormant.

      • Today I called Bimeda the makers of Equimax and asked a bunch of questions. The girl had the Vet call me back. I spoke with him in detail and he claim’s that Equimax will kill the adult neck thread worm. I have not read anywhere that supports such a claim. I am finding now that I can get through for 3 weeks before my horse starts scratching again. The Vet for the company assured me that Equimax is safe for extended uses but advised me not to de-worm as often due to other worms building up a resistance, mainly strongyles. What I find ironic and odd about our conversation is that on the box of Equimax and in the package insert, it clearly talks about the microfilariae, but not the adults. I’m going to call the makers of Strongid tomorrow and I’ll post what they say tomorrow.

        • Hi Pam

          The current advertising for Equimax Elevation, which I’ve just read on the Virbac Australia site, does indeed state Onchocerca threadworms as well as microfilariae. I’m going to inquire about the research, because to date I’ve not seen any research papers showing effectiveness against adult worms, in horses or humans. I’m curious to know which chemical of the Equimax trio is working on them, out of Ivermectin, Praziquantel and Pyrantel.

          Tip: ask which research journal the paper is published in when you hear something surprising.

          More will follow!


          • Thanks for the reply Jane. He said he was 100% sure it kills the adults. I’ve also called a local Vet here who has a large facility. We talked for quite a long time and he also claim’s ivermectin will kill the adults. I myself have done quite a bit of research and I do see where in people it is only manageable by killing the microfilariae. I messed up in the post above. I’m calling the manufacturers of Zimecterin. I’m going to go onto the internet tomorrow and pull up as many products that contain ivermectin and call them. I’m really curious and interested in hearing what they have to say. Good question though, about what is killing them, if that is the case. And, I will ask if there are any studies done that they can direct me to. I’m not seeing the adults being killed off in my horse, because he is still rubbing his tail, but not nearly like he was. The Vet I spoke to today said then its not neck thread worms. He also claimed that horses do not get the lesions down the back, only on the underside, chest, face, and neck. My horse didn’t have them down his back, but on Google images it shows such. I will add that my horse has made a really big improvement even though I don’t think he’s out of the woods quite yet.

          • Okay, so, I’ve contacted Merial in regards to Zimecterin Gold, which states it kills the microfilariae on the box. It does NOT kill the adults. The rep suggested anyone dealing with neck thread worms and has used zimecterin gold to contact them and give updates on what has taken place with your horse. By law they have to file a report. I’m totally not sure what is going on with Equimax and their vet, but they are closed today and I’ll be contacting them again on Monday. These de-wormers are regulated by law, so I’m not sure why the makers of Equimax didn’t take a report. Will keep this updated for everyone dealing with this.

            • I thought about this a lot yesterday. Please refer to the above article for why affected horses might develop hypersensitivity and ‘the itch’, ie tail head sensitivity, as a consequence of reacting to neck threadworms… I think I need to write another, shorter post too about the spaces in the research and why not all horses are showing the belly patches.

              I just wish some professionals would, instead of stating “there’s no research to state this so therefore it cannot be” might look a bit wider and say, “well there’s this observation, and there’s no answer for it that we know of, and so maybe there’s a gap in the research”.

              And so much for evidence-based veterinary medicine – here we apparently have companies offering products that are endorsed by their own salaried vets, whose word customers are supposed to accept, yet for which there doesn’t appear to be any published data.

              Can I just clarify, Pam, which products are being claimed as being effective against adult onchocerca?

              • Hi Jane,

                I’m in the USA, not sure if that really matters. I hear you and totally get where you’re coming from. I do research for a living so this is really bothering me. More so, I’m bothered by this, because of my horse. I myself had to convince my own Vet that my horse has them. It was quite an argument because he had just attended a seminar on worms, during the seminar, it was stated, by a worm expert, that Neck Thread Worms were not a problem in this area. I see lots of horses, and I can say, its a serious problem here. Both the Vets I spoke to in my area now agree and believe horses are being misdiagnosed. The Vet I spoke to yesterday was from Bimeda, the makers of Equimax. I did not get his name, but I’m going to call back and get it on Monday. This is only for my own reference and is no way to doubt what you’ve researched. I’m just trying to get to the bottom of this myself. I find it hard to believe there isn’t something out there to kill the adults. And if there isn’t, then I’m going to push for a product. I’m also looking into holistic treatments.

                The Zimecterin label states Ivermectin 1.87% and Praziqantel 7.75%
                The Equimax label states Ivermectin 1.87% and Praziquantel 14.03%

                So could it be possible that the higher dose of Praziquantel in the Equimax is killing the adults?

                • I was asking because I’m in Australia and the branding is sometimes different… when you look at the Australian websites, they also all carry the safety sheet (downloadable PDF) which has licensing information it. This is effectively the small print on the leaflet inside the packet, although of course you have to buy it for that.

                  I’d be very interested in learning about how they’ve tested for this. Most papers show testing at necropsy, with multiple samples taken as slices from the nuchal ligaments. I assume this is done at the point of death, so that living adult worms can be identified. Biopsies on living horses are going to be limited by ability to hit the right area, ie where the living worms are located, and by only accessing those that are near the surface.

                  Also, are results gained in the lab or, as above, from case studies, pre and post-mortem?

                  Ivermectin and the other ‘mectins’ work on the central nervous system of the parasite and effectively paralyze it. Nothing I’ve read shows a chemical that can work on the CNS of the adult worm. Huge research has been done because of ‘river blindness’, the ocular problem occuring in adults affected by the human Onchocerca Volvulus. It is an established fact that ivermectin kills only the larval worms and that people are having the microfilariae ‘managed’ through twice a year ivermectin doses. If another chemical were effective, it would surely be in use… Praziquantel for human use, is effective for types of liver fluke, ie types of flatworm that inhabit the blood in their later stages. In other words, a different type of parasite entirely.

                  My feeling is that Onchocerciasis in horses is little understood by many, beyond the dermatological effects. The focus is naturally on intestinal and blood-born worms.

                  Good luck Pam, and please feel free to email me and discuss this off-site:

                • Hi Pam
                  Any more update on your research? How’s it go with your horse? Just found out my horse has this. Picked it up in his boarding facility, and the managers been trying to hide the fact that 3 horses on property had it and its spread. I’m really pissed off as you can figure. I’m wondering is there no way to surgical remove adults? Maybe fine them with an ultrasound? My horses is a show horse….. Or well was… I’m going to try everything for him.

                • I just wanted to make an observation re NTW V skin irritation.
                  Some horses rub their necks & shoulders & pretty much rub themselves raw including loosing their mane, causing serum exudate & making the skin lumpy.
                  Other horses get under a strong branch or rail & push up hard to get in deep into the top of their neck right infront of the wither usually. I have seen this type of rubbing further up the neck but less so.
                  In doing so they often rub out their mane & a lot of hair. But the pattern of rubbing is different.
                  The method of rubbing is different.
                  The horse rubbing it’s skin, rubs it’s neck up & down vigorously against something rough or rubs crosswise side to side under a rough branch that may be very bendy.
                  The horse trying to get deep into the tissue pushes up hard under the sturdiest biggest branch or rail they can find & just about lifts it out of the ground & works at getting in deep in one spot.
                  They don’t always actually rub out the hair or mane completely although they often do shorten the mane because it gets broken off.
                  I feel the horse rubbing in deep is trying to ease the discomfort of the NTW chewing inside the nuchal ligament. It must be terribly uncomfortable.
                  The horse that has a skin irritation of some kind needs to rub the skin raw to get rid of the offending critter, parasite or fungus.

                  What got me thinking about this in so much detail was a few years ago I had what I was convinced was a worm or bot in my bicep muscle. It felt like something was chewing me apart from inside a hard lumpy bit. It all but drove me mad. If I grabbed hard at the area & wrenched it around, the ‘chewing’ stopped for a while.
                  My doctor told me I had a misfiring nerve & gave me a medication that homed in on such nerves & quietened them. It worked so long as I took the medication, which of course has undesirable side effects, so I do tend to stop taking it after a while until the discomfort of the ‘chewing’ gets too much again.
                  So if a horse does infact have something in it’s nuchal ligament that is chewing it apart from the inside, the discomfort would be maddening.
                  No wonder they want to rub deep & hard as they can to stop it.

                  My mare has a favourite branch that has a 2inch wide stump protruding downwards where I cut off a low hanging branch. She gets up against that stump part & pushes up as hard as she can & works it into the side of her nuchal ligament in one particular place.
                  She doesn’t take much hair off although she does shorten the mane at that location.
                  She must have a few adult worms in there because at other times I see her doing same thing at other locations along her neck.

                  I think I have gotten the NTW microfilia under control in her. I did the big worming program right before the mozzies came out this year & now she is having far less reaction to them.
                  It is obvious there is some sort of interaction between NTW & mozzie season as I mentioned in an earlier post re the protozoa & microfilia.
                  She is scratching a bit under her belly but not anywhere near the extent she was a few years ago. Just only what I would expect to see from all the horses due to the numbers & kinds of mozzies around right now.
                  She hasn’t torn out the hair under her belly or caused those long lines to develop or made the skin scaly etc.
                  So at this stage it’s all good this year so far.

                • Hi Zoe,
                  I have been treating my horse for NTW for about 2 months under a vet’s care. It’s been a bit of a nightmare. I gave her ivermectin every two weeks as prescribed and the vet also prescribed Dex for itching. She had a horrid reaction to the Dex and colicked twice. The second time was quite intense and the vet said it’s too coincidental that she colics with Dex so we stopped it. I decided to give her a probiotic and she was so much better after that. I’m thinking all the dewormer and the Dex, plus Banamine for colic, was too much on her digestion. The vet never prescribed a probiotic, but it’s just what she needed. I highly recommend giving probiotics, before and along, while treating for NTW. Maybe it will save someone the trauma of a colic episode. We also had an emergency vet call after she sliced open her chest, requiring stitches. The itching was so intense she was scratching her chest on anything and everything. I would really like to bring an end to these NTW!

                • Hi Pam,
                  I was reading over your posts here and was looking for an update. I would like to know if you have any information to conclude with the Equimax and a possible protocol for treatment?? I discovered my horse to have the neck worms about 2 years ago but know he has had them for way longer. He is 18 and I have owned him 16 years. I ‘m sure there are many horses out there with infestation since it is not diagnosed properly. I am very interested in finding a treatment for my horse that gives us both some relief. Thanks.

                • Hi, I’ve removed your publicly displayed email address, as this site does attract the spammers now that its traffic has grown. Pam, let me know if you’d like it and I’ll pass it on. Thanks, Jane

        • Denise Adams says:

          My vet just had me double dose with equimax and two weeks later double dose again. I bought my boy Splash last spring, I thought I caused the itching due to leaving conditioner in his mane. He began rubbing his beautiful mane out. Come winter it began to slowly grow back… than BAM this spring his mane is gone! He has a section about 6inches long that is bare and sore. He has started to rub his tail too.
          Thank you for all the information. I will continue to fight this Damn parasite! Any new information is welcomed.

      • Hi I bought a hose a couple of years ago seems nothing wrong with him then, but with-in no time at all he started itching to the fact he was almost removing his skin on shoulders tons of vets visits, visits to equine clinics allergy to this allergy to that and so on and so forth.
        having read several of your links I have tried the worming and success I nearly have a horse complete with skin, but I’m worming with Noromectin every 10/12 days we live in Somerset, England.

        • Hi Teresa

          You are the second person I’ve heard from recently living in Somerset and dealing with this issue.

          It’s so good to hear that you are having success with the worming. You shouldn’t need to keep it up so intensively once you’ve got the problem on the run. The idea is a high dose to knock the microfilarie numbers back, and then a maintenance level for a year. After that, worming more seasonally, in response to the breeding cycles of the culicoid flies and NTs.

          If you need more specific advice for the ongoing regime, it’s a good idea to get on the Chronicle of the Horse forum and post there, as there seem to be hundreds of people who’ve been working on this with their horses.

          I lived in Somerset until a few years ago and am incredibly pleased to hear that work I’m doing in Australia is helping some horse people there!


        • That is really interesting and I’d never heard of neck worms before!

        • My paint QH itched his face so bad, he would cut it open and rub the hair off. He also experiences patchy hair loss. Both him and my other QH would Itch their shoulders out so bad, they would take the skin off and have raised huge welts. I live in Scottsdale Arizona USA.
          Anyway I first did double dose Panacure for five days, then a few weeks later, did the ivermectin wormers, every two weeks, for three weeks. My Paint ( the one that itches worse, of the two) did get worse. To help him thru this process I did give him 4cc of vetalog or kenalog. Really helps stop the itching.
          Anyway the last dose was two weeks ago. His hair has grown back and he has stopped itching! Neither of mine rub their manes out. Just face, shoulders and occasionally their bellies a little.

          • I meant to say hair off on the shoulders. Not skin.

          • Wondering if you’ve had recurring issues with NTW? My draft-cross mare had the itchy chest/neck andI just did one dose ivermectin. Will follow up with vet and administer more on a schedule. A couple welts, and a couple threadlike indentions from mane down neck about 5 inches… So weird to have this in AZ, but we’ve had a wet spring/summer in Cave Creek.

            • I have since lost my paint to cancer. But still have my 20 year old. So far this summer he has only rubbed one shoulder once. About the size of a lemon. I swear I just thinks its fly’s biting him.
              I keep my place so clean too. Pick up horse poop 4 to 5 times a day and sprinkle diatomaceous earth on top of horse manure in the dumpster.
              I have two new horses that also get effected with hives. Drives me crazy,
              Unfortunately from everything I read. It does seem to be environmental with the hives.
              Also switch to several all natural fly sprays.
              I’m on FB. Look me up and we can talk.
              Patty Bailey. I have a picture of my husband and I and then my back round pic is 3 horse butts! Lol

        • Hi Teresa, please contact me. I too an in the UK Birmingham)
          My 2.5 yr old (I’ve owned him 6 months, he came from Germany) has started leaning on edges of shelters and incessantly rubbing shoulders and neck and throat/underside of neck only. It started when using a natural wormer and I’ve excluded anything I can think of causally.

          • I think a 2.5yo is far too young to have NTW.
            It takes years for the worm to invade the nuchal ligament & more years to mature to reproduce.
            It’s one of the main signs when aged horses that have never rubbed before all of a sudden begin rubbing around mane & where neck joins withers.
            In the case of your horse, if you rug him, you may find there is some sort of fungal thing or mite living in the material of the rug that is causing irritation around base of neck & withers.

          • I’m agreeing with Clarissa here, in that it’s possible you have other causes there. While young horses do have neck threadworms, the itching reaction is (I believe) more associated with the size of the parasitic population, which is associated with the size of the culicoide fly population. For example, my horse developed the extreme reactions at 6yo, the year after a particular wet year on the sub-tropical humid coast of northern NSW. (Last week an English veterinary paper was published linking the rise in liver flukeworm cases in horses in the UK to a couple of extremely wet years – humidity favours all of these critters!)

            As far as I know, exactly how the microfilaraie travel to the nuchal ligament hasn’t been established. It is hard to track a microscopic organism deep in the living horse! Clarissa, where did you read about how long it takes the adult onchocerca to start reproducing? I’d be very interested to take a look at that – and I’m being genuine here, not querying your information.

            Fiona, by natural wormer, I assume you mean herbal? This won’t touch non-gastric neck threadworm microfilaraie – only ivermectin will work. Nor will it help with the dangerous encysted small strongyles – see the other article on the dangers of these. That’s why NTW became a far less common parasite after the 80s, when people started using ivermectin-based wormers regularly. If your horse was wormed by the breeders you bought him from, it’s less likely that you have a reaction to NTW happening already.

            All that said, I’ve heard from people with unusual presentations in their horses that don’t match the existing research, so there’s never any harm in ruling it out. Usually, these are horses with NTW in places where the parasite is said not to exist. But again, we have horses travelling more than ever, and variation in climatic conditions. A single dose of ivermectin or moxidectin should give you an answer.

            • Jane it’s one of those bits of info that has been floating around in my head for many years.
              I remember a seminar I went to in Maleny in the late 80’s run by a horse wormer company touting the new ivermectin chemical & how effective it had been against those families of worms & bots in humans in Africa. How the worms migrate through the system & come out through the skin or stay deep in muscles & how irritating they were. One worm heads for the brain & sends it’s host mad but doesn’t want to kill the host. Others depended on the host scratching so badly that the skin is broken to allow the worm to hatch.
              I also have some recollection of more recent info that young horses produce a chemical or hormone that fends off some worm types. Older horses loose that capacity so any encysted worms that hatch get a good go.
              It might not have been Onchercerca cervicalis parasite per sa but certainly Onchercerca family that migrates through the system. Some go to the skin to breed so the young hatch out through the skin while others stay in other parts of the body.

              This life cycle stuff I read was years ago in a photocopied handout at a free seminar on horse worms run by a wormer company that used ivermectin. At that time it was touted to get into all the soft tissue of the horse.

              This next bit came from a horse wormer chemical website:- the worm matures to a certain point in the gut(or maybe it was the blood) & mates, then migrates to a ligament, usually the nuchal but sometimes the Suspensory ligament in the leg. The burrowing process takes a fair while & then the worm only reproduces during the warmer more humid months in response to certain triggers.
              That’s why in the back of my mind there is this 14yo age for the host horse.
              It could be that I have the life cycle of other worms mixed up with Onchercerca in general.

              I recon I have read most of what you have read Jane over the years & maybe I put various bits of info together to draw a conclusion relating to the extended life cycle of Onchercerca cervicalis. I tend to think a lot more laterally & extrapolate to see beyond what has been written or work past the current situation that the particular horse was in that caused the writer to note their findings.
              When I see a horse that rubs just the one or two spots on it’s mane makes me think the encysted worm is right under that spot & it’s gnawing of the nuchal ligament is very irritating so the horse rubs that area very hard to get in deep.

              • Thank you! I wrote a long reply earlier and then lost it, so this will be a bit brief. I’m guessing you live in an affected area?

                It’s a different species, O. Reticulata, that is found in suspensories, but in the research it’s not reported much.

                I still haven’t read anything about O.C migrates through the digestive system – that makes more sense with the worms that ingested with food from the ground. It must travel via some bodily fluid, after the MF are ‘delivered’ by the culidoides. It is such a strange thing, but then parasites are!

                Thanks again.

  2. large pony mare 27yr old, developed sweet itch 2 yrs ago, tx w IV and IM and oral Dex for 7 days each year, managed with fly sheets etc.
    I double dosed 2 weeks ago w oral ivermectin (actually it turned out to be a triple dose, stopper didn’t work) and there has been no itching response.
    sorry if i feel unclear, but is this a negative test then, to NTW?
    Sheila, Langley, BC Canada

    • Hi Sheila, thanks for posting. It’s possible that your mare’s immune system is low due to age-related conditions, so maybe she needs a little more nutritional support that before? Apologies if you’re already onto this. With no itching response to the ivermectin, it’s less likely that neck threadworms are the issue, as it really is an intense response when you see it, and quite unmissable.

      • thank you for response, yes to nutritional support, coming a little late as she has been practically a breath-arian hard working horse still, (earth/metal) and as a result of sudden recent dropping weight/ tooth root infection, antibiotics pre and pro biotics organic apple vinegar etc etc she’s now enjoying enormous amounts of premium hay and senior mashes, I am starting acupuncture and herbs to support health and vitality. thanks for this great forum!

  3. Cathy whitney says:

    I live in California in the USA, and I have been fighting NTW for just a little over 2 years on my 12 yr. old Appy/QH mare. She had a bald area on her mane and the midline area on her belly. She does the itchy splay on the ground to scratch her belly. After an initial double dose of straight ivermectin twice a month for about 6 months, we are on a regiment of one double dose a month, and her mane is grown in and long and beautiful. However, she still has a line of missing hair on her belly. I am now using Picardin 20% spray to ward off the midges. It has really helped over the last 2 weeks. No new bites, and she is not as itchy. I purchased it on Amazon, and the manufacturer is Natrapel. I haven’t read anything negative about this product..what I have read it that it is as effective as deet without the hazards. Has anyone else used this product, and if so how did it work?

  4. Rochelle says:

    I have been hearing that there is a correlation between Ivermectin use and hoof abscesses in horses. Does anyone here know of any truth to that? I have not been able to find out anything myself.

  5. Hello….love these articals….finally nice to see someone looking for what works instead of what their books have stated. I manage and own a boarding facility in Washington state were there are lots of ponds and its wet a lot. Giving 2 Equimax,wait two weeks then give two more seems to work. It is so hard to explain this to people when some of the “professionals” say this is not good. Also had a bad lung worm out break due to bringing in a donkey…I had thought was de-wormed and save. Many thousand of dollars later we discovered it was lung worms. So now we double dose once a year and de-worm every 28 days.

  6. Angela.S says:

    I have a rescue QH mare that came to me with a bald blistering, scaley, itchy face. As long as I treat her face with vitamin E oil and or neem oil it’s not as inflamed..if I miss a day it’s terribly bad. I was told it was eczema then sunburn.. but why the hair loss? So I researched and kept coming back to NTW. I did the test and gave her the ivromectin and on the third day she broke out in bumps on her chest and face was itching really bad..she was rubbing everywhere. I’m starting her on a herbal worming regime with probiotics and garlic. As these actually go through the blood stream. I hope I’m on the right course with treatment. I’ll post my results as I see them. I would like to attach pictures but I don’t see that option here. Thanks for the informative write up and will continue to follow..

  7. Are the one in the legs treated the same way as the ones in the neck?? My horse has sores covering his front legs, a few on his back legs, the ones on his belly, all over his shoulders, a little on his neck and face and ears. None on his back and he’s not rubbing his tail or mane as far as I can tell. I was about to disregard the neck threadworms because his legs are itchy, but now I see there is the one in the legs too…. do you treat it the same way?

    • Yes, all can be treated with ivermectin or moxidectin.

      • Susan Dossett says:

        Jane, I have been reading this post and am not clear on the prescribed treatment. I have a 17 yr. old paint mare that I have had for 13 yrs. I first started treating for Sweet Itch and then, after doing some research, realized that what I was dealing with was NTW. I tried worming her continuously with an herbal wormer last year and her symptoms did improve, but we also had a very dry late summer and fall here in Central Texas. I have read the posts that say herbal wormer a don’t work. Could you please e-mail the protocol for the wormers. Also, I read the post about Equimax- would that be an option? My email is:!

  8. Dear All
    There is a warm inside my Pony eye and the length is around 3cm. Several tratmnet done and still liveingt.
    The treatmnets are Ivomectine and fenbendozol

    Please help me


  9. My big glossy fat rolly poly QH mare broke out in this itch 3yrs ago all of a sudden & rubbed herself raw in the typical locations almost overnight. It was the lines of lumps all along her belly midline & the way she lifted her leg like a dog to scratch herself under the belly & between the back legs that really got my attention. After all the usual attempts to solve the problem I heard about NTW on COTH & spent hours reading the thread.
    This year I went to a seminar put on by VIRBAC (I’m in Qld, Australia) about worming & FEC. I spoke to the lady & took advantage of the free FEC’s & the results were as expected re all the usual culprits but of course nothing re NTW.
    So I drenched all my horses Imax Gold (invermectin) single dose 2wks apart x 3times, then the Strategy (fenbendazole?) once after another 2wks. The weather has been mostly warmish with rain during the final 2wk stage which all would have been good for causing worms to hatch & encysted worms also to hatch. My mare certainly did get a lot more itchy after the first 2 wormings but I didn’t notice a higher itch level after the Strategy. ‘They’ (the chemical companies) now say to use Strategy all through the spring & summer then back onto ivermectins for the autumn/winter which is different to previous advice.
    My mare is still itchy but no where near as bad as before worming. Plus they now spend the day in a treeless paddock so no opportunity for her to scratch. However she runs to the tree when she gets home each night but doesn’t rub her hair out like before.
    Her coat is still rough although she is putting on a bit of weight. The new hair coming through also seems rough so that would tell me she is still infected or afflicted & in general her system is still suffering. I have improved her nutrition which has been a bit of a shock since she was an ‘airotarian’ or ‘breath-arian’ meaning she lived on smell of an oily rag. Now getting copious feeds & supplements but obviously still something missing.
    My other horses don’t seem to itch although 1 does scratch the backs of his pasterns a lot with sharp teeth so perhaps he has the worm in the suspensory ligament or DDFT.

    RE ROCHELLE in May who asked about ivermectins causing laminitis & abscesses. Yes I have found this to be a big issue with 2 of my horses, 1 laminitic/sunk/foundered on all 4 feet with bad abscessing but now recovering due to my diligent barefoot trimming investigations/education/applications & the above mare laminitic but not sunk or foundered. It always seems to be worse after worming but I was told it is the dying worms that cause the inflammation & I am happy with that explanation. I stretched my worming out to 4xyr to avoid those side effects but now have this NTW issue. So not sure which is worse!

    • Hi, mites can also be a culprit with itchy pasterns, as you probably know – it sounds as if you’ve looked into just about everything!

      With spreading the worming out to 4x per year, are you still using barrier treatments to reduce the fly bites? It’s interesting to hear about people’s combination approaches…

      My horses have just moved up to the Tablelands, where it’s so much cooler, but I’m still seeing them itch. Right now, I’m trying down to knock back the MF population before the warmth of spring, although so fewer flies up here than on the coast, I should be able to get this problem under control.

      • Just an update re my mare with NTW. Over the last summer 2014-15 she oscillated between scratching like crazy & not scratching at all. I tried to keep records of mozzie outbreaks & rainy humid periods but nothing seemed to correlate. In general it was a hotter & more humid season than usual.
        Then in March I began giving all my horses a home made probiotic made from carrot & cabbage all munched up, salted & stored in a very large bottle to turn to a type of vinegar for 4wks a bit like sauerkraut. All very complicated but they liked it & my mare seemed to heal up. Now I’m not saying the probiotic did the job, it was just co-incidence as it occurred at the same time as cooler nights, less rain & mozzies. She is hardly scratching & has a full winter coat. However she is still scratching her underbelly.
        But I will be doing the trial again as soon as the season gets into insect mode again.
        During the winter season I will just do maintenance worming but I was thinking of using Equest this week as an alternative to my usual Imax Gold although it is still an Ivermectin variant I think.
        My other horses are not scratching at all thankfully.

    • Thank you!! Very interesting. It’s hard trying to sort this out. The worming really seems to help now… Still not sure if the ivermectin is connected to the accessing. She is certainly less itchy. Hmmmm. Would love more feedback from others.

      • Well no sooner did I post the update than my mare broke out again scratching one small spot halfway along her mane like there was no tomorrow! There are lumps right under it in her nuchal ligament, might be caused by the rubbing but might be a NTW.
        She is also scratching other parts now so today they all get wormed AGAIN! She will be done double & again in 2wks. If her reaction has been to the microfilia then I am right onto them because there are no mozzies, sandflies or any other biting insect at this time. I love this time of year. I call it the Benign Season! We often get a similar few weeks in early spring.
        I’m also suspecting some sort of protozoa influence in her gut. Does anyone know if there is a correlation between NTW & a protozoa colony in the gut? These critters have a cycle that is around 25-30days long & they cause various ill effects to their host like gut & colon inflammation, immunity upsets, brain cloudiness, nerve problems to name just a few.

        • I meant to add that I am wondering if there is a synergistic relationship between the NTW & a gut protozoa where the NTW might also give off a chemical signal to the protozoa when it sheds it’s microfilia to cause an irritation that aids the microfilia.

  10. I know I’m on an old post but I have been dd fortnightly for 5 times now, itching has lessened to belly and tail area, shall I keep going I don’t know when to stop dding ! A little advise needed please.

    • HI Juli

      No problem. Great news that you’re getting somewhere!

      The advice in the second article is to continue with a dose once a month during the first year, and then drop down to a more seasonal approach during the second year. It’s something you’ll need to look at on an ongoing basis, as the adults live for over 10 years and can’t be bumped off.

      I hope that helps 🙂

    • It’s in the article, Juli. Drop down to once per month for 12 months, maybe adding in the extra dose here and there during peak seasons for the midges – Spring and Autumn.

  11. Hi, Thank you for the very informative article. I think I may be dealing with NTW in my mare. I live in South Florida, USA and the day after I gave her a dose of ivermectin she broke out in tiny very itchy bumps along the side of her mane. She has also been unusually itchy on her back this summer with small crusty, bumpy spots appearing sometimes around her hip areas. My question is, do you treat with monthly single doses of ivermectin? Or dd?

    Currently I am doing rotational deworming every 6 weeks so she gets ivermectin, fenbendazole, z-gold, and pyrantel. Can I treat NTW and still rotate dewormers? I also plan to do a Panacur power pac and not sure how long I should wait (before and after) between that and regular worming? Any help or guidance would be appreciated. Thanks

    • Hi Julie

      It’s in the articles… the initial dose and then regular worming but on a more frequent basis. Use ivermectin or Quest in the ‘high’ seasons, ie spring and autumn. Quest will hit the worms that aren’t affected by ivermectin.

      For ongoing advice, it’s a good idea to visit the Chronicle of the Horse forum, where you’ll probably find people who live in your region.

      All the best


      • Julie Steinfath says:

        Hi Again Jane, I treated my mare in Sept last year for NTW with single dose ivermectin every two weeks for 3 weeks on the advice of my vet. However, he also prescribed her Dex and it caused her to colic very badly twice. Her hind gut took a pretty good hit so she’s on daily probiotics now and doing much better. I’m going to start treating for the NTW again as the weather is warming up and I was wondering, as you mentioned about the strongyles- if I have done a single dose of fenbendazole will that work to ensure no huge problem with those? You mention the Panacur Power Pac (DD for 5 days), do you think that is that necessary if she has had fenbendazole 3 times in the past year? Just trying to cover all my bases before starting treatment again. Thank you.

  12. hi
    I’ve been reading up about itchy horses and different reasons why it may be, my boy for last couple of years and especially for this year as been horrendous with itching, I’ve tried everything for him and really don’t feel i’m getting anywhere with him, he is itchy all over his body but mainly his tail, mane, neck and especially shoulders to put i cant stop him itching and he is making himself extremely sore. i found him in his stable one day where he had rubbed that much he had open sores covering his shoulders.
    Just wondering if it sounds he may be suffering from ntw, i will try anything to try and make it easier for his day to day living.he’s living out currently as i cant stable because of his itching and I’ve just put him onto epsom salts as been advised to de- tox him, the vet as been out and given steriod injections and hes had blood taken and everything as come back clear from allergies etc
    i’m at a total loss and just want him to be happy and comfy as much as poss

    many thanks kelly

    • Hi Kelly

      The information is in the article – if you’ve read both, it should make sense.

      I have a small group of people in the UK dealing with neck threadworms and can put you in touch with them if you wish? Most seem to be in areas where there have been floods in the past 2-3 years, or higher than normal rain with warm weather, and therefore a larger midge population.

      • cath byrne says:

        Please could you tell me what areas of the uk?

        • In Somerset, after the Levels flooded, and also Worcestershire in the same period. I assume there’s a low existing population of NT, but an increase in the culicoid fly population upped it sufficiently to take some horses into the reactive state.

  13. Thank you for this article on thread worms, I believe one or both my horses have been battling this for many years and I never knew about them.
    Since the day we bought Merlin (black and white paint) he has suffered from bouts of extreme itchy face and shoulders. Literally raising welts, cutting himself and hair loss on his face.
    Some….but Not to much mane rubbing. Some belly rubbing in the past too.
    I have a picture I would like to send you or post, showing these ridges on his body.

    • Hi, I’m glad to hear that the articles (there are 3) have helped you with your horses. It can be so traumatic for them.

      I have nowhere on this site to post pictures of individual horses, although they’re really interesting. Can I suggest the NTW threads on the Chronicle of the Horse forum? There’s a huge number of people exchanging experiences there.

      I hope all goes well!

  14. Jessika says:

    Hi there , I also have a very itchy horse I’ve tried everything on the market from Qi ease in his feed to Qi serum Itch magic quit itch, shield & permoxine have done nothing he’s rugged with a hood drenched in incesticide but is still scratching I’ve watched him go from tree to tree driving himself insane , I have just started him on Preddy Granuels today , after reading your article I’m going to also start ivermectin worming double dose as of tomorrow, as he’s had this for over a year this is the first time I have heard of the neck worms causing the itch all signs are pointing towards it ? Will keep you posted

    • The thing I think I discovered with my mare’s itching was the particular way she scratched & where on her body she scratched.
      One of the indicators of NTW are lines of scabs or tiny pustules running parallel along the horse’s belly from chest to groin. My mare was using her eye teeth to tear that area open & to some extent she still does due to ever present mozzies. Although it is not nearly as bad now & there is no scabbing.

      But the part that got my attention was where she rubbed her neck & the way she did it.
      She was rubbing into the top of her neck but not the outside or the skin.
      She was getting up under a low strong branch & seemed to be getting right deep into her neck like giving herself a deep tissue massage of the extreme variety!
      She did rip out a lot of mane but not nearly as much as when she just rubbed her skin raw.
      She was getting way in deep just infront of her wither & using the whole of her strength & all 4 feet, was working slowly back & forth just a few inches without actually rubbing the skin. So she was working the inside of her neck not the outside if that makes sense.
      Sometimes she worked her neck cross ways then length ways but always getting in deep.
      My thoughts on that were that she was trying to get at something that was irritating her inside her muscles or the nuchal ligaments.

      Nowadays she still rubs a bit but now she rubs her skin. I haven’t seen her go for the deep massage for ages.
      I haven’t done the NTW double worming for a year or maybe more & she has retained her hair coat through all of the mozzie season pretty much intact. There were times this past summer when she was covered in large welts from the very large scotch grey mozzies & even now in this drought we still have little black mozzies that bite at ankle height.
      We are having an extremely hot Autumn/winter like it is still summer & the mozzies are still here so the horses haven’t had a break from them yet.
      There are even sandflies or what might be known as midges or maybe no-see-ums.
      None of these make her scratch more than a bit & never enough to rub her fur off.

      So I think I did Jude 3 times for the NTW worming process & between her deep tissue massage & the worming, I think the thing is dead! hooray!! This coming Spring will tell if that is fact. 🙂

      • Susan Dossett says:

        I have been following this post for some time, but am not clear on the protocol for worming. Is it double dose of ivermectin then wait 2 weeks and double dose again at the start of the season??? i definitely want to try this next spring as we go into the season for these things to become active as my mare has had them most of her life(she his 17!) and I have tried EVERYTHING! Please let me know what you did to break the cycle. I would love to give her some relief!!!

        • Hi, thanks for your question. Yes, you have the dosage right in your second sentence. Double dose ivermectin … 14 days… double dose … 14 days… double dose.

          Vets also give this protocol: Single dose ivermectin……… one month…….single dose……….one month… single dose.

          The suggestion in this article is that you can continue with this protocol throughout the first 12 months, particularly in horses where the parasite is well established.

          Where do you live? I’d love to hear how you get on. Best of luck!

      • I just want to update to say now that it is spring here, Jude seems clear of the NTW.
        She scratches her skin a little probably from mozzies or midges.
        But the deep chronic scratching seems gone thankfully.
        In past years by this time of year, her head, neck, shoulders, withers & belly would be almost hairless.
        Jude recently turned 20yo so that might be another indicator that the worm is now dead.
        She outlived the rotten blighter! 😀

        • Great news that she’s comfortable at last! However, although she may have outlived some worms (plural), others will have been younger and will remain now, as they are not affected by the wormers. HOWEVER you have certainly hit the microfilaraie, which cause the ferocious itching. I’m so pleased for your mare!

    • Jessica please try a Kenalog/vetalog shot from your vet. 4 cc. I promise it will help your horse and you will see it with in 24 to 48 hours.
      I have two itchy horses and four dogs with different issue. One horse gets a horrible itchey face and sometimes shoulders, another gets hives on his legs and also rubs his shoulders. I keep my place so clean, wash the horses weekly in the summer. Have fans, misters etc. when they get the itchiness, nothing stops it but this shot. Nothing.
      They will and can get itchy when you worm them with Ivermectin, by the way.
      Also Kenalog works on my dogs itchy butt, another two that get the hot spots. Clears everything up.
      I just came from getting my nails done and my nail tech said her doctor gives her a shot of kenalog and all her allergies have gone away. She has been doing it for a couple years.
      I didn’t even know they gave it to people.
      I actually buy a few bottles and give my own injections. 4 cc for my horses with last two months.
      Dogs get way less.
      I guarantee you this will help. Please come back and reply to this and tell us how he or she is doing.

  15. Frank Purdy says:

    A twist, My horse suffered two years with belly lesions and insessent scratching. Three vet opinions, many treatments with no success. Our children gave my wife a gift card to Barons Book store. While waiting for her I went to the equine section an pulled a equine vet encyclopedia. I found a chair and began reading every description of equine skin diseases and low and behold was there was a complete discussion of the thread worm with the Invermection treatment. The encyclopedia did not discuss the frequency of treatment so I found your articles and evolved the treatment for my horse. Thank you Jane.

    • Fabulous. I never tire of hearing these positive responses! I didn’t ‘discover’ anything here, but am very happy to have compiled an article that brings it all together in one place. May I ask which country and region you’re in, please?

      • Frank Purdy says:

        Jane, I live in CA 30 miles South Sacramento. Last year I used Invermection several months and belly iching stopped and hair grew back. With flooding and having to move horses to safe haven, worming protocol was interupted. This spring iching began with some belly hair loss. I have gone back to the monthly protocol and the iching is worse with more belly hair loss. Two months with third coming May 15th. I use Invermection topically daily. Should I go to a double dose biweekly or stay with the monthly dose?


        • Hi Frank, how frustrating for you. Unfortunately when there’s a major wet and warm period, the culicoid flies multiply, and our problems return tenfold. If it were my horse, I would consider starting the protocol over at the beginning after this set back. The other place you can ask is on the Chronicle of the Horse forum, where they may be people from your zone dealing with a similar upsurge. I wish you luck, it’s a horrible thing for your horse to experience.

  16. Has any one here tried Yucca? (Sorry if you’ve already posted about this). My horse kept scratching off a section of mane, he didn’t have crusting on his chest or neck (but my other horse had a bit of that) I rotate conventional wormers and powerpack but nothing seemed to work. I tried things like MTG and tea tree oil herbal sprays. Nothing.At one point he had a 3″ completely bald spot. Anyhow, I started feeding Yucca, apparently, it kills protozoa and has been used on EPM horses. My horses is a large tb/Friesian, and finally, finally, his mane is beautiful, wavy, thick and even!

  17. This has been a very informative and eye-opening post re NTWs. Every symptom mentioned re itching, where, how, how long, treatments – have been through and seen in my mare. Vet looked at a photo I had on my cell phone but did not come out to SEE my horse when I brought her in for a Coggins. Two months later, worse than before, called, got a Rx for an antihistamine (hydroxyzine) and another for an on-going script. Later got asked if my horse’s breathing had improved. WHAT! She itches and is breathing fine. Tech says ‘oh, that’s what we prescribe for breathing problems.” That told me the vet and/or tech had no clue what this mare had or was going through. Today, another month later and after reading this thread and others I TOLD them she had all the symptoms and what did they recommend. She said Ivermectin now and again in two weeks. I think this may take longer than that to eradicate.

    Since I’ve done natural worming for many years with no worms showing up in the vet-done fecals – the NTWs may have taken over. Should I switch back to the chemical rotation every two months and forget my natural routine or do the natural and every 3-4 months hit the horses with one of the rotational wormers? One of my gelding (21 y.o.) is starting to rub his neck and another gelding at the moment seems fine. I do see the little hard nodules just under their skin – on all three. Remember a friend who had a vet dig out one of those bumps and it was a white worm….this was many years ago so these NTWs pests have been around a long time. 🙂 I don’t think my friend’s horse had issues beyond that bump (or more??) but she is a chemical everything – horses, dogs, cats, people. I’m just the opposite.

    Again, a great thread. Learned so much. Thanks.

    • Hi, ivermectin or moxidectin will keep the population of microfilaraie down, so should eradicate symptoms if done consistently at first, and then consistently during the busy fly seasons. Remember these are microscopic and will not show up unless captured in a biopsy, after which the tissue is mashed prior to study. The adult worms are visible so it’s possible one was captured in a biopsy. The earlier studies of NTW were conducted around 1910 – it’s only with regular worming programmes that its incidence has been knocked back in recent decades.

      • Lauren, Redding CA says:

        Just wanted to thank you. After a year of double worming, And another year of double worming in the summer-Fall, I have seen tremendous improvement. In my way of thinking, please tell me if incorrect, if the Adults worms can live for 10 yrs. they and the itching accumulate up until double treatment; so Treatment will take a few years to eliminate them as they die off.? Just worried about to much worming for my horse, but they really have improved over the last two years. It was just as you said, double worming, 1-2 weeks tremendous itching, bumps appear, better for a couple of weeks then cycle repeats. I two was told by vet they were not in our area.

        • Hi Lauren, great feedback, thank you. It sounds as if you’re on top of it. If this were my horse, I’d be dropping the worming down to single wormers, maybe monthly with fortnightly at peak times. That’s if the reactions seem to be diminishing. All you can do is try it and see!

  18. 35 days after last(week apart) Equimax dosing of my 19 yr old pony. Her eyes are still discharging and the itch is starting again. Vet is coming on friday. Is there a test, blood, skin, or pooh, or a biopsy that they can do so that they’ll believe me? The worming reaction was diagnostic as far as I’m concerned. We live in a temperate rain forest ,in midge heaven and I’m well acquainted with sweetitch, which this is not. Any advice on salves for her eyes please? She had a similar attack last year at the same time (late Autumn) but it went away after the double dose and she had no response to the wormer on that occasion. This time it has not been nice for her. After the test, if they do one, I will be worming again with Ivermectin and will keep doing so until she is free of symptoms. Feel very alone in this, good to know I’m not a loony with weird imaginings! Any advice would be most welcome. Thank you, Lyn.

  19. Ly, I’m sorry to hear that you’re having such a distressing time with your pony.

    If you check back in the article, the onchocerca can be diagnosed through a biopsy of the nuchal ligament, which is straightforward. It’s covered in the veterinary dermatology manuals – I found it online via Google books. However, if you have recently wormed, then there’s a chance that the count will be lower or even showing as not present. You may wish to leave it another month to be sure, even though it’s difficult not treating your pony in that time?

    If she’s not shown such bad symptoms before, then I’d certainly be working at building her immune system – her age may be making her more vulnerable, particularly with the reaction around the eyes.

    I hope you get somewhere with addressing this.

  20. Vetericyn spray soothes infected eyes…can spray it straight in.

    Also, don’t forget to use fly eliminators around your barn during fly season. I get mine from Arbico…and they really help keep the population down. I’m going to start earlier this year and see if it helps my overall program. I’ve got two draft mares that are battling neck threadworms. The wormer protocol has definitely helped. Hoping this year to get on top of it and keep them both healthy. Using probiotics and going to try harder to keep the flies away with screening and fly sheets as well as wipes.

  21. Thank you Sara.


  1. […] Read the follow-up article, posted October 2013: How to Fight the Big Fight Against Neck Threadworms […]

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