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Bodywork

Here’s a Round Up of My Premature and Dysmature Foal Research

May 26, 2022 by Jane @ THB Leave a Comment

Here are abstracts, downloads and links for my research into the ongoing effects or premature or dysmature birth in horses.

These are the publicly available details of my thesis (full download) and published, peer-reviewed journal articles. The articles aren’t open access, but if you really want to read something, please contact me.

As always, huge thanks are due to the breeder owners who so very kindly allowed me to study their horses, and who provided such valuable images. Together, you’ve helped me to learn a lot and reach initial findings that I now hope to pass on.

 

Beyond the Miracle Foal: A Study into the Persistent Effects of Gestational Immaturity in Horses 

PhD Thesis, University of New England and CSIRO

Abstract

Breeding horses can be a financially and emotionally expensive undertaking, particularly when a foal is born prematurely, or full term but dysmature, showing signs normally associated with prematurity. In humans, a syndrome of gestational immaturity is now emerging, with associated long-term sequelae, including metabolic syndrome, growth abnormalities and behavioural problems.

If a similar syndrome exists in the equine and can be characterised, opportunities for early identification of at-risk individuals emerge, and early intervention strategies can be developed. This thesis explores the persistent effects of gestational immaturity manifest as adrenocortical, orthopaedic and behavioural adaptation in the horse.

Basal diurnal cortisol levels do not differ from healthy, term controls, but when subjected to a low dose ACTH challenge, gestationally immature horses presented a depressed or elevated salivary cortisol response, suggesting bilateral adaptation of the adrenocortical response. This may be reflected in behavioural reactivity, but the outcomes from a startle test were inconclusive.

A survey of horse owners indicated that gestationally immature horses tended to be more aggressive and active than controls, aggression being displayed mostly in families of Arabian horses. Case horses also tended to be more active, intolerant, and untrusting.

Gestationally immature horses have restricted growth distal to the carpal and tarsal joints, and this results in a more ‘rectangular’ conformation in adulthood compared to controls. They also often present with angular limb deformities that adversely affect lying behaviour and recumbent rest. This, however, can be mitigated using analgesic therapy, suggesting chronic discomfort.

Based on these findings, it is reasonable to postulate that a syndrome of gestational immaturity may persist, both clinically and sub-clinically, in affected adult horses. Further work is required to fully characterise this syndrome and validate the outcomes in larger populations, thereby providing a foundation for interventions applicable in the equine breeding industry.

Here is the downloadable doctoral thesis. This is a 236-page PDF.

Clothier, Jane  (author); Brown, Wendy  (supervisor); Small, Alison (supervisor); Hinch, Geoff  (supervisor)

 

Equine Gestational Length and Location: Is There More That The Research Could Be Telling Us?

Australian Veterinary Journal

Abstract

Clear definitions of ‘normal’ equine gestation length (GL) are elusive, with GL being subject to a considerable number of internal and external variables that have confounded interpretation and estimation of GL for over 50 years. Consequently, the mean GL of 340 days first established by Rossdale in 1967 for Thoroughbred horses in northern Europe continues to be the benchmark value referenced by veterinarians, breeders and researchers worldwide. Application of a 95% confidence limit to reported GL range values indicates a possible connection between geographic location and GL.

Improved knowledge of this variable may help in assessing the degree of the neonate’s prematurity and dysmaturity at or soon after birth, and identification of conditions such as incomplete ossification of the carpal and tarsal bones. Associated pathologies such as bone malformation and fracture, angular limb deformity and degenerative joint disease can cause chronic unsoundness, rendering horses unsuitable for athletic purpose and shortening ridden careers.

This review will examine both the factors contributing to GL variation and the published data to determine whether there is potential to refine our understanding of GL by establishing a more accurate and regionally relevant GL range based on a 95% confidence limit. This may benefit both equine industry economics and equine welfare by improving early identification of skeletally immature neonates, so that appropriate intervention may be considered.

The paper can be accessed here.

Clothier, J., Hinch, G., Brown, W. and Small, A. (2017), Equine gestational length and location: is there more that the research could be telling us?. Aust Vet J, 95: 454-461. https://doi.org/10.1111/avj.12653

Using Movement Sensors to Assess Lying Time in Horses With and Without Angular Limb Deformities 

Journal of Equine Veterinary Science

Abstract

Chronic musculoskeletal pathologies are common in horses, however, identifying related effects can be challenging. This study tested the hypothesis that movement sensors and analgesics could be used in combination to confirm the presence of restrictive pathologies by assessing lying time. Four horses presenting a range of angular limb deformities (ALDs) and four non-affected controls were used.

The study comprised two trials at separate paddock locations. Trial A consisted of a 3-day baseline phase and 2 × 3-day treatment phases, during which two analgesics were administered to two ALD horses and two controls in a standard crossover design. Trial B replicated trial A, except that as no difference between analgesics had been evident in trial A, only one analgesic was tested. Movement sensors were used to measure the horses’ lying time and lying bouts.

In trial A, ALD horses’ basal mean lying time was significantly less than controls (means ± SD for ALD horses 213 ± 1.4 minutes and for controls 408 ± 46.7 minutes, P = .007); with analgesic administration, the difference became nonsignificant. In trial B, ALD horses’ basal mean lying time was also significantly less than controls (ALD horses 179 ± 110.3 minutes; controls 422.5 ± 40.3 minutes, P < .001), again becoming nonsignificant with analgesic administration. Given the increases in ALD horses’ lying time with analgesic administration, it is possible that their shorter basal lying time is associated with musculoskeletal discomfort. Despite the small sample size, movement sensors effectively measured this behavior change, indicating that they could be a useful tool to indirectly assess the impact of chronic musculoskeletal pathologies in horses.

The paper can be accessed here.

Clothier J, Small A, Hinch G, Barwick J, Brown WY. Using Movement Sensors to Assess Lying Time in Horses With and Without Angular Limb Deformities. J Equine Vet Sci. 2019; 75:5559. doi: 10.1016/j.jevs.2019.01.011

 

Prematurity and Dysmaturity Are Associated With Reduced Height and Shorter Distal Limb Length in Horses 

Journal of Equine Veterinary Science

Abstract

The long-term effects of gestational immaturity in the premature (defined as < 320 days gestation) and dysmature (normal term but showing some signs of prematurity) foal have not been thoroughly investigated. Studies have reported that a high percentage of gestationally immature foals with related orthopedic issues such as incomplete ossification may fail to fulfill their intended athletic purpose, particularly in Thoroughbred racing. In humans, premature birth is associated with shorter stature at maturity and variations in anatomical ratios, linked to alterations in metabolism and timing of physeal closure in the long bones.

We hypothesized that gestational immaturity in horses might similarly be associated with reduced height and different anatomical ratios at maturity. In this preliminary study, the skeletal ratios of horses with a history of gestational immaturity, identified through veterinary and breeder records, were compared with those of unaffected, closely related horses (i.e., sire, dam, sibling).

External measurements were taken from conformation photographs of cases (n = 19) and related horses (n = 28), and these were then combined into indices to evaluate and compare metric properties of conformation. A principal component analysis showed that the first two principal components account for 43.8% of the total conformational variation of the horses’ external features, separating horses with a rectangular conformation (body length > height at the withers), from those that are more square (body length = height at the withers). Varimax rotation of PC1 and analysis of different gestational groups showed a significant effect of gestational immaturity (P = .001), with the premature group being more affected than the dysmature group (P = .009, P = .012). Mean values for the four dominant indices showed that these groups have significantly lower distal limb to body length relationships than controls. The observed differences suggest that gestational immaturity may affect anatomical ratios at maturity, which, in combination with orthopedic issues arising from incomplete ossification, may have a further impact on long-term athletic potential.

The paper can be accessed here.

Clothier J, Small A, Hinch G, Brown WY. Prematurity and Dysmaturity Are Associated With Reduced Height and Shorter Distal Limb Length in Horses. J Equine Vet Sci. 2020 Aug;91:103129. doi: 10.1016/j.jevs.2020.103129. Epub 2020 May 22. PMID: 32684267.

 

Perinatal Stress in Immature Foals May Lead to Subclinical Adrenocortical Dysregulation in Adult Horses: Pilot Study 

Journal of Equine Veterinary Science

Abstract

The persistent endocrinological effects of perinatal stress due to gestational immaturity in horses are unknown, although effects have been reported in other livestock species. This pilot study tested the hypothesis that persistent adrenocortical dysregulation is present in horses that were gestationally immature at birth by assessing the salivary cortisol response to exogenous ACTH.Case horses (n = 10) were recruited with histories of gestation length < 315 d or dysmaturity observable through neonatal signs. Positive controls (n = 7) and negative controls (n = 5) were recruited where possible from related horses at the same locations.

Cases and positive controls received an intramuscular, low-dose (0.1 ug/kg) of synthetic ACTH (Tetracosactrin 250 mg/mL, Synacthen); negative controls received no ACTH. Saliva samples were collected from all horses at baseline T = 0 and at 30 min intervals post injection from T = 30 to T = 150. These were assayed for salivary cortisol concentration (SCC) using a commercially available ELISA kit (Salimetrics).All baseline values (T = 0) were within normal published ranges. Peak and AUC values (corrected for baseline) for case horses were significantly different (ANOVA P < .001) to positive controls, with either higher (H-cases) or lower (L-cases) SCC values, outside the 95% Confidence Interval of the reference population.

There was no significant effect of breed, age, sex, test month, or location on results. The results suggest that gestational immaturity may lead to subclinical adrenocortical dysregulation, with affected horses presenting an elevated or blunted response to a low-dose ACTH stimulation, despite normal basal levels.

The paper can be accessed here.

Clothier J, Small A, Hinch G, Brown WY. Perinatal Stress in Immature Foals May Lead to Subclinical Adrenocortical Dysregulation in Adult Horses: Pilot Study. J Equine Vet Sci. 2022 Apr;111:103869. doi: 10.1016/j.jevs.2022.103869. Epub 2022 Jan 21. PMID: 35074402.

Filed Under: Bodywork, Foals Tagged With: dysmature foals, equine anatomy, equine bodywork, equine dysmaturity, equine prematurity, GA, horse anatomy, immature foals, Premature foals

Yes, We Can Image for Transitional Vertebrae in Horses

September 23, 2021 by Jane @ THB 7 Comments

It’s been a question of mine for a while. Can diagnostic imaging show the presence of transitional vertebrae?

We’re seeing many bone samples from dissections, as shown in my previous article on transitional vertebrae.

But if we’re to help our horses that live with this issue, we need to identify it before they’re dead. (Yes, right?!)

Allow me to introduce a practicing vet and educator who is doing just that.

 

Imaging for Transitional Vertebrae 

Meet Dr Brunna Fonseca, Associate Professor, educator and specialist in equine orthopedics, focusing on the spine and nervous system. She’s based in São Paulo, Brazil.

I’ve been following her Instagram for a while, because she posts brilliant videos and photos explaining what she does, and how, and why.

I was delighted to see a recent post on imaging for a transitional vertebra, which included fantastic visuals. Such a great communicator!

Dr Brunna has kindly given me permission to repost her images and descriptions here. So without further ado…

  • All images copyright of Axial Vet

Ultrasonograms

Ultrasonography for transitional vertebrae
Angle of transducer. Image: Equine Neck and Back Pathology: Diagnosis and Treatment, 2nd Edn. Ed. Frances M.D. Henson. © 2018 John Wiley & Sons, Ltd.

The following ultronographic images are each a composite of two images, one showing the left side and the other the right.

This textbook illustration helps to show the angle the image is taken at. This angle is usually used for imaging the articular facets of the vertebrae.

Additionally, the image at the top of this article shows a transitional vertebra at T18, like the mare being diagnosed by Dr Brunna.

 

1.  Can we recognise transitional vertebrae?

The first image shows two sides of a mare’s body. The hand icon gives us a strong hint of where to look… This appearance is very similar to that of the TB mare in my previous post.

Dr Brunna writes, “This mare has the T18 transitional vertebra, presenting a transverse process similar to the lumbar vertebrae on the right side, which causes the appearance of the horse to have the most visible rib on that side.

The occurrence of transactional vertebrae in the horse is not uncommon, especially in the thoracolumbar transition, which can occur in T18 or L1.”

 

2. Section of a thoracic vertrebra

This image is from a different horse showing a normal rib head and its joint with the vertebra.

Dr Brunna writes, “This is the image of a thoracic vertebra, showing the costotransverse joint.”

 

3. Image of a normal vertebra

Dr Brunna writes, “This is a T17 ultrasound image, where we can see the image of the normal costotransverse joints.”

This is the bay mare again.

As with the previous cross section, the red pins which show the facet joint between rib head and vertebra.

 

4. Section of a lumbar vertebra

This is cross section is of a normal lumbar vertebra from a different horse.

As you can see,  there is no joint between the  transverse process and the vertebral body.

The process is wide and flat, and integral to the vertebra.

 

5. Image of a lumbar vertebra

Here’s an ultrasound of the first lumbar vertebra (L1) in the bay mare.

As in the above cross section (picture 4), there is no joint between the transverse processes and the vertebral body.

We now have ultrasound images of the normal T17 and normal L1. As we will see, the transitional vertebra mixes elements from both.

 

6. Imaging transitional vertebrae

“This is an ultrasound image of T18, where we can see the image of the costotransverse joint on the left side (red pin) and image of the transverse process on the right side.”

So here’s the underlying skeletal issue in the bay mare.

The left side is a normal joint, being the same as the T17 thoracic vertebra (picture 3).

The right side is similar to the previous image of the lumbar vertebra (picture 5).

It is not identical, for while the process-like rib is joined to the vertebra, it is not the same shape and does not lie as flat as the lumbar process.

 

Want to Hear More From Dr Brunna Fonesca?

You can follow her Axial Vet Instagram page to see examples of her equine cases and their assessment, in images and videos.

An increasing number of captions are now translated into English.


 

 

 

 

 

Filed Under: Bodywork Tagged With: Anatomy, equine anatomy, equine bodywork, equine malformation, equine skeleton, GA, horse anatomy, transitional vertebra, transitional vertebrae

10 Rehab Tips for Horses with High-Low or Upright Hooves

January 1, 2021 by Jane @ THB 9 Comments

 

Sorting out that high-low hooves situation. It’s the farrier’s job, isn’t it?

Well yes, they’re clearly the primary professional. But there are plenty of things you can also do to help.

As their horse’s bodyworker, I’m often the first to tell an owner that unbalanced forefeet are causing problems right through the body.

Related issues can include ringbone, carpal arthritis, shoulder asymmetry, base of neck arthritis, atlas rotation, TMJ issues, spinal rotation, scoliosis and even sacroiliac dysfunction – all depending on the severity and duration of the hoof issue.

That’s not me being dramatic. In an older horse, that’s absolutely the type of problems I can find when there’s a long term high hoof.

And don’t forget, there are the saddle fit issues that go along with all of that.

Here, in plain speak, is the list of rehab tips that I offer my clients, so that they can help their farrier to help their horse.

 

© All text copyright of the author, Jane Clothier, https://thehorsesback.com. No reproduction of partial or entire text without permission. Sharing the link back to this page is fine. Please contact me for more information. Thank you! 

 

Before We Start: Choose Your Hoofcare Professional Well

It’s obvious, but this is essential.

Hoofcare professional
No problems here! Megan Matters trims 3.5 month-old Fjord, Lodur (c) Karen Groneng, Greenfield’s Stud

Engage a hoof professional who walks the walk as well as talking the talk.

This is someone who can tell you about hoof function and how the ‘normal’ hoof works during loading and movement.

This is someone who frequently updates their professional training.

Professionals who take continuing education are informed about current research into hoof function, as well as methods to address problems.

They know a lot more about current best practice and are more likely to demonstrate it, too.

This most definitely isn’t someone who relies solely on the apprenticeship they completed many years ago.

How it helps:

Skilled hoofcare professionals will aim to achieve a similar height in the two front hooves, even though the hoof angles may be different when viewed from the side.

They will trim each hoof according to its underlying structure, making corrections where needed.

They will NOT simply try to create similar angles and toe length, which creates stresses in a high hoof, and sets your horse up for numerous hoof and body problems.

With a skilled hoofcare practitioner on board, there is plenty more you can do to help your horse through this process of change. The more effort you put in, the more your horse will improve.

 

1. Use Variable Feeding Positions

Variable feeding positions were first described by Sharon May-Davis, who recognised their value as a form of passive physio.

Haynet at poll height
(c) Jane Clothier, equinehealthworks.com

This one is easy: hang a haynet at poll height to replicate eating from trees. This encourages the horse to stand square while eating.

You’ll gain the best results from small hole nets, as your horse will twist her head from left to right while eating. She’ll also drop down to eat hay from the ground.

Doing so activates the deep muscles beneath the neck vertebrae. It also activates the muscles beneath both shoulder blades as she shifts her weight one foot to the other.

If you feed more than one net a day, place the other at chest height.

How it helps:

Think thoracic sling and freeing up the restrictions that have arisen from stabilising the weight over different height limbs, as well as adopting a ‘scissor’ position to eat (which will have contributed to the problem in the first place).

 

2. Introduce Different Surfaces

The hoof balance is changing, but there may still be asymmetries in your horse’s body that are slow to shift.

Horses on varied footings
All horses seem to appreciate the stimulation of new surfaces during hoof rehab for a variety of issues. (c) Tanja Kraus Horsemanship

Standing your horse on different and unfamiliar surfaces can make the body’s self-adjustments happen quicker.

If you’re able to put some down, gravel provides wonderful under-hoof stimulation. Sand too. Your horse can tilt his hooves toe-down, heel-down or side-down, as he wishes.

Interlocking mats are also effective and can be used anywhere, as can commercially made physio mats and pads.

Watch your horse become curious, start relaxing and yawning, and you know that body adjustments are happening from within.

How it helps:

It can take the nervous system a while to wake up and catch up with what’s new.

The horse has sensory nerves in the feet, and new surfaces provide different proprioceptive.

It’s not just the hoof – changes in balance are registered from the many neuroreceptors of the lower leg.

As the parasympathetic nervous system (‘rest and repair’) is activated, musles are allowed to relax and reset.

 

3. Feed on a Slope

Again, think thoracic sling. The horse must open up the spine at the cervico-thoracic junction (base of neck).

Feeding on a slope
(c) Jane Clothier, equinehealthworks.com

It’s also next to impossible to adopt a scissor position (the foreleg grazing stance, see no. 7 below) when eating on a slope.

How it helps:

Your horse is encouraged to load into the front hooves equally, left and right.

Finally, the soft tissue structures at the back of the leg will be gently stretched on the limb with the upright hoof.

 

4. Rock the Withers

Standing alongside your horse when she is standing square, gently rock the withers from side to side.

Rocking the withers
(c) Jane Clothier, equinehealthworks.com

Hold one or two wither processes at a time (feel for the ‘buttons’) and swing gently from one side to another.

This makes the horse load into one forefoot, then back into the other.

Do this from both sides to ensure equal work, as most of us are either stronger pullers or stronger pushers.

How it helps:

The horse is being asked to mobilise between the shoulder blades. When there’s restriction, she’ll raise a hoof on the swing away from that leg.

Easing any restriction will help with relaxing the shoulder on the high side and allowing the joint angles to open out.

She may dislike the exercise at first if it’s uncomfortable, but it will improve over time. You are also gently mobilising the spine deep to the shoulders.

 

5. Massage the Neck Muscles

When there’s a high foot, the restriction and reduced movement on that side (the stride and therefore leg swing is often shorter) will transfer up through the shoulders to the neck.

Tension also builds because the horse is trying – and failing – to balance their weight centrally.

This is a secondary effect, caused by the horse’s changed posture.

Pay particular attention to the fine muscles behind the poll, which will be imbalanced.

How it helps:

Releasing muscular tension will help the horse to move to a more symmetrical posture through training and postural improvement.

 

6. Good Old Carrot Stretches 

Use pieces of carrot to encourage stretches to either side.

This will help your horse to become more familiar with loading into both forehooves to a more equal degree.

Lateral carrot stretch
(c) Jane Clothier, equinehealthworks.com

There are many variations on these stretches and everyone has an opinion!

If you try to ensure that your horse is standing square in front, these stretches will help, whatever the exact approach.

How it helps:

The horse is stretching out the shoulder and neck muscles, including those beneath the shoulder blade, which are going to be more restricted on one side than the other.

This action will also stimulate and activate the deep spinal muscles, bring fresh ‘body awareness’ to the region (ie, proprioception).

 

7. In-Hand Grazing Tricks

Does your horse have an obvious ‘scissor’ grazing stance, as in the first photo (right)?

Grazing stance
Change is difficult at first! (c) Jane Clothier, equinehealthworks.com

If you horse’s high hoof is always the one at the back, then there is more you can do.

Try to spend up to 20 minutes a day feeding your horse in-hand.

Walk with her and let her graze, but ONLY allow her to do so when the upright foot is placed either level with the lower foot, or further ahead.

This means lots of stepping forward, stopping, stepping again, until she’s stood as you’d like.

This will be hard for your horse at first, as you can see here, but should become easier over time.

How it helps:

As grazing positions became long term, they also familiar and are adopted habitually. It’s like folding our arms or crossing our legs in one direction.

As the hooves become balanced, the horse will continue adopting the ‘old’ position.

This is a way of reprogramming your horse as the hooves start to become more balanced.

 

8. Daily Leg Stretches 

This is where little and often really helps. Perform gentle leg stretches forward.

Don’t haul the leg, but allow your horse to take up the last inch or so herself.

Foreleg stretch
(c) Jane Clothier, equinehealthworks.com

If there’s a lot of tension, go very gently and don’t stretch to the limit.

Let the cannon hang vertically from the knee, so you’re only extending the upper leg.

A hand behind the elbow will help and your encourage your horse to ‘pop’ the last part of the stretch.

Don’t force it. It’s not about physically lengthening muscles: you’re allowing signals to reach the brachial plexus (nerve centre behind the shoulder blade).

Watch out for your horse looking down and touching his own knee as you start doing this, almost as if he’s surprised to see it there.

How it helps:

This is far more than a muscle stretch! You are influencing the horse’s nervous system’s awareness of the forelimb’s joints and muscles, and the leg’s position in relation to the body and then the ground.

This is proprioception and it will benefit from some help in resetting itself at shoulder joint level.

This ‘resets’ the leg and improves awereness around various joints’ range of motion.

 

9. Joint Mobilization

The hoof height is changing and becoming more equalized, meaning there’ll be changes higher up the legs as well.

(c) Jane Clothier, equinehealthworks.com

The high hoof side will have to open out a bit, while the low hoof side will be slightly less extended than before.

This involves the soft tissue structures around joints, particularly those of the fetlock and pasterns.

Do you ever see horses shaking their hooves or rotating their lower limb? No.

Your horse is likely to love you for gently rotating and flexing the lower joints, allowing structures to move in different ways, where previously they have been limited.

Pasterns above an upright side are likely to feel stuck. Above an underrun hoof, they will feel loose.

How it helps:

Mobilizing the joints through gentle rotation helps to restore range of motion where it has been restricted.

Spaces will be opened up that allow fluid to circulate, lubricating the joint and bringing more freedom to tendon movement.

This all helps the horse to stand above the changed hoof, positioning the leg closer to where it needs to be.

 

10. Work Over Poles

Many horses with long toes have a tendency to trip. Once again, as the hoof balance changes, they need to adjust their sense of ‘where their feet are’.

Top: Ground poles (c) FEI.org Bottom: Extending the exercises to the trail (c) Tanja Kraus Horsemanship

Working over poles helps your horse to focus on individual hoof placement, in terms of both stride length and height of motion.

This can be done over ground and raised poles, or over logs on the trail.

For stronger input, back your horse over poles.

Lead him over with one fore foot, then back with that foot. Lead him over with both forefeet, then back with both. And so on, until the horse knows how to navigate during back-up with all four feet.

How it helps:

Once again, it’s about the proprioceptive input.

As well as ‘equalizing’ your horse’s awareness of its feet, you’re correcting for any lasting effects of pain.

Pain in one hoof and the joints above it has a negative effect on proprioception. Same if two hooves are affected by pain.

By doing this kind of work, you’re helping your horse’s nervous system to ‘square up’, along with the feet.

 

There’s more – there’s always more. For example, make sure that nutrition is adequately providing the building blocks for hoof growth, development and strength.

As you get going, you’ll find that these are not so much short term changes for rehabilitation, but part of a move towards a more proactiveway of managing your horse.

(c) Jane Clothier, thehorsesback.com

 

 

Filed Under: Bodywork Tagged With: bare hoofcare, bare hooves, barefoot horses, club foot, farrier, farriery, feeding positions, GA, hay high, high-low hoof, hoof trimming, natural hoofcare, upright hoof, variable feeding positions

Cost of Survival: The Lifelong Problems of Premature and Dysmature Foals

July 23, 2020 by Jane @ THB 21 Comments

Were you around when your horse was born? If so, you’ll know about their neonatal health. If you weren’t, then understandably you don’t.

Your horse could have been a premature or dysmature foal and you might never, ever know.

Why is this a problem?

Well, anyone who’s been around me or reading my posts here over recent years will know that I’ve been researching the developmental issues experienced by premature and dysmature foals – or more specifically, the problems they carry forward into adulthood.

It’s an under-researched area, but I made some headway. Last year I was awarded my PhD for Beyond the Miracle Foal: A Study into the Persistent Effects of Gestational Immaturity In Horses.

In my thesis, I included studies that showed some of the lasting developmental effects in some (not all) horses with a history of prematurity or dysmaturity at birth. (Many twins are dysmature, by the way. Fascinatingly cute, but frequently devastatingly dysmature.)

You see, a lot of gestationally immature foals don’t just ‘get over it’, catch up and become exactly the same as they would have been had they not had problematic gestations. Some do, but many don’t.

Here’s the lowdown from my own research – which I’m convinced is the tip of the iceberg.

 © All text copyright of the author, Jane Clothier, https://thehorsesback.com. No reproduction of partial or entire text without permission. Sharing the link back to this page is fine. Please contact me for more information. Thank you!

Changes Linked to Prematurity and Dysmaturity

Conformation

Physically, they tend to have restricted distal limb growth and a more ‘rectangular’ conformation. I’ve published a paper on this in the peer reviewed journal, Journal of Equine Veterinary Science (JEVS).

Behavior

Owners indicated in a survey that affected horses tended to be more aggressive, active, intolerant and untrusting than closely related horses. This was more evident in the so-called ‘hotter’ breeds and in mares (no surprise on two counts there!).

Orthopedic issues

Angular limb deformities, a fairly common orthopaedic issue, can adversely affect these horses’ recumbent rest. This means that they find it harder to rest for the typical 20-30 minute bouts, a fact that could adversely affect valuable REM sleep. Again, I’ve published on this subject in JEVS.

Stress responses

When a low dose ACTH challenge was administered, these horses presented a lowered or heightened  salivary cortisol response. In other words, they have a different adrenocortical response to stress to closely related horses. As the adrenalin and cortisol ratios are affected, they may stay stressed for longer after a stress event. Different stress responses can affect health, learning, training, and quality of life.

Developmental Programming

There’s more – a lot more. This is part of what’s known as Developmental Programming, or the Developmental Origins of Health and Disease (DOHaD).

Previous researchers have established disorders including:

  • differences in hypothalamic-pituitary-adrenal axis function,
  • differences in pancreatic beta-cell function, and
  • glucose metabolism, plus
  • effects due to neonatal stress in pony foals (and clearly, weak or premature foals may experience neonatal stress, whether they are ill or not).

Don’t understand that? It doesn’t matter. All you need to know is that these studies already point towards pathologies such as kidney disease and Equine Metabolic Syndrome, plus a different physiological responses to stressors.

A Syndrome of Gestational Immaturity

In my view, there is definitely a Syndrome of Gestational Immaturity in horses.

By the way, gestation length on its own isn’t a good indicator of how badly a foal is affected, unless they’re extremely premature (here’s my paper on gestation length variability in the Australian Veterinary Journal).

There’s a wide range of possible problems – some horses have some of them, other horses have others, and some have none at all. They’re individuals, while everything else in their experience and care makes a difference too.

That’s how it is with syndromes. And right now, it’s all flying completely under the radar.

These are silent problems that are only recognized when they rear their proverbial ugly heads further down the line – if they are recognized at all. My heart aches for these horses and ponies, for many do not find life easy.

(c) Jane Clothier, The Horse’s Back.

Filed Under: Bodywork, Foals Tagged With: dysmature, dysmature foals, equine dysmaturity, equine prematurity, foals, GA, gestational immaturity, miracle foals, premature, Premature foals

All About Crooked Legs: Angular Limb Deformities in Horses and Foals

April 5, 2020 by Jane @ THB 9 Comments

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Angular Limb Deformities: it’s the technical term for crooked leg problems. The term sounds alarming, but how bad are they and exactly how common?                                                    

We’ve all seen shocking pictures of crooked foal legs in groups and forums, but thankfully they stand out exactly because they’re not so common.

However, many horses have mild or moderate versions of these. And what is normal is that many tend to slip under the radar, undetected by owners and breeders. And that’s not a good thing.

Image (c) Nådhammar on Flickr

The problem is that moderate angular limb deformities (ALDs, as we’ll now call them) can create bigger problems as the horse grows older, with increased risk of lameness, instability, and joint degeneration. 

They can cause complications when the horse is injured elsewhere in the body and needs to compensate, but can’t, because the non-straight limbs are already under pressure.

To repeat: many ALDs aren’t an issue. In fact, many are so mild that they’re never a problem.

The thing is, you need to know the difference. And that means knowing what to look for.

Some are obvious, others need veterinary radiographs to be sure. For all of them, the earlier you catch them in foals, the better. Always talk to your vet first.

So without further ado, here are ten ALDs you really ought to know about.

 

© All text copyright of the author, Jane Clothier, https://thehorsesback.com. No reproduction of partial or entire text without permission. Sharing the link back to this page is fine. Please contact me for more information. Thank you!

1. Carpal Valgus

‘Knock Knees’

Carpal valgus (c) vetstream.com. Additional markup: THB.

This is the most commonly seen ALD in foals and horses. Technically it is an outward deviation of the lower leg from the mid line. Most of us see the other effect – the knees coming closer together.

In foals, the hoof often points outward. In older horses, the hoof may turn inwards – this is compensation to bring weight bearing back in.

There may have been a fetlock valgus (see #3) lower down, which has then caused the carpal valgus higher up.

This can be congenital. It can also be acquired, as a result of physitis of the radial growth plate immediately above the knee at a few months of age.

Incomplete ossification, when the carpal bones are underdeveloped at birth due to dysmaturity or prematurity, can contribute to this problem.

Key points: ALD of forelegs; knock-kneed appearance; lower leg angled outwards; affects one or both forelegs.

 

2. Tarsal Valgus

‘Cow Hocks’ (mistaken for)

Tarsal valgus in a foal (c) Redden, RF [1]
This is an ALD that very often gets mixed up with the conformational trait of cow hocks. To further confuse matters, mature horses with back issues may also stand unusually behind.

In these limbs, the point of hock angles inwards, while the lower limb angles outwards. Often, the pasterns are also angled outwards, giving a splay-footed look. In walk, the foot will swing in and then land wide.

The entire leg may be rotated out from the midline, as in this image.

In older horses, the medial heel may be crushed or under run.

Key points: ALD of hind legs; lower limb or whole limb angled out; affected hinds land wide; affects one or both limbs; one limb often worse.

 

3. Fetlock Valgus

‘Toe Out’

Fetlock valgus. (c) unknown. Additional mark-up: THB.

It’s extremely hard to find a picture that shows a fetlock valgus with no other visible limb deformity. Even the mild ones tend to be associated with rotation at knee level (see #10).

This is when the pastern and therefore hoof are angled away from the midline, below the level of the fetlock.

The valgus in this photo is reasonably clear, although there’s some rotation in the knee. Note that the foal is weighting this limb less and an upright foot is already starting to develop.

Key points: usually ALD of forelegs; sometimes with tarsal valgus in hind legs; one or both feet angled outwards; one often worse.

 

4. Fetlock Varus

‘Toe In, Pigeon-toed’

Fetlock varus (c) Stephen O’Grady [3]. Additional mark-up: THB
A fetlock varus is also often confused for conformation or a horse ‘just being like that’. 

With this problem, the foot is angled towards the midline below the level of the fetlock,

This problem is often combined with offset canons or rotated carpals (see # 9,10), as the foal is compensating in an effort to bring the weight bearing line back beneath the shoulder joint.

In older horses, the lateral heel may be crushed or wear down quicker. Depending on severity, there may be a tendency to ringbone in later life.

Key points: usually ALD of forelimb; affects one or both legs; often accompanied by a carpal ALD.

 

 

 

5. Carpal Varus

‘Bow Legs’

In a carpal varus deformity, the lower leg is angled inwards, towards the midline. Our eye tends to see it as the joint being angled outwards.

Advanced carpal varus (c) unknown

You don’t often hear about bow legs in horses, do you? That’s because it’s rare.

It’s usually seen in older horses, when the problems have layered up. Arthritis may already be present in the joints, while tendons and ligaments may have lesions.

Some may have had lax ligaments at birth, or have ruptured the common digital extensor tendon at a young age, causing misalignment of the carpal bones.

Key points: rare ALD of foreleg; bow-legged look; foot dishes inward; arthritis and lameness likely.

 

6. Flexural Deformity

‘Contracted Tendons’ (so-called)

This is a common deformity in newborn foals (call your vet).

Sometimes it affects the carpal (knee) joints only and the foal is still able to use the lower leg quite effectively. Or, it affects both the carpal joints and the fetlocks, leading to a more serious situation where they can’t walk on the hoof.

Severe congenital flexural deformity (c) J. Clothier

This can also be an acquired deformity related to incorrect nutrition during the first weeks and months of life. In these cases, nutritional measures, remedial hoofcare and even surgery may be required .

The hind legs can also be affected, although this is less serious as the direction of joint flexion encourages correction.

Mild cases in foals can often come right on their own in the first days of life with a little help. However, it is always important to involve a vet at an early stage for monitoring.

Key points: ALD mostly affecting forelegs; either knees only or knees and fetlocks.

 

7. Hyperextension

‘Lax Tendons’

Again, this is super-common in newborn foals and it can often resolve all on its own in the first few days of life with a mix of confinement and limited exercise.

Hyperextension in the hindlimbs

Occasionally, in the case of dysmature and premature foals, the problem can be more complex. Combined with incomplete ossification and lax ligaments, hyperextension can lead to another level of ALD, as the cuboid bones of the carpals and tarsals become misshapen.

Once more, give the foal a couple of days to straighten up and then talk to your vet if it persists.

Key points: affects forelegs and hindlegs often together; usually resolves with conservative exercise; support for limbs and hooves may be required.

 

8. ‘Windswept’

This startling looking deviation is often seen in foals that are  post-mature – they have had a long gestation and have been restricted within the uterus.

What we’re looking at is a combination of ALDs: carpal valgus and varus in front, and/or a tarsal valgus and varus behind.

The problem will general resolve within a few days, sometimes with a bit of hoofcare and bodywork to assist.

However, if the foal appears weak despite being ‘over-cooked’, with hyperextension (#7) as well, be sure to monitor it especially carefully during the early weeks and months. This is because incomplete ossification may also be present.

Key points: affects forelimbs and/or hindlimbs; hyperextension may also be present; often resolves in days. 

9. Offset Cannons

Offset cannon (c) horsesidevetguide.com Additional markup: THB

Strictly speaking, this is a conformational trait, as it often visible in the sire or dam. However, it is still classified as an ALDs on account of the structural weaknesses involved. 

In the offset cannon, the cannon bone is positioned wider than the midline of the leg, although it still faces forwards. The hoof is also forward facing.

In one leg, this ALD may have no negative effect on athletic performance. Yet if present in both forelegs, the horse may be less stable in some situations, such as going downhill.

It increases the chances of two things: developing a splint (medial leg) and a tendency for the foot to turn inwards, which could then lead to an acquired fetlock varus (see #4).

In racehorses, it can increase the chance of injury in the medial carpals, while other sports horses may be prone to osteoarthritis in the joint.

Key points: cannon appears shifted sideways; cannon, hoof and knee face forwards; usually inherited conformation; medial splints more likely.

 

10. Carpal Rotation

‘Bench Knees’

Rotated carpals with associated fetlock valgus. (c) unknown. Additional markup by THB.

In this ALD, the cannon bones are rotated slightly outwards, as are the lower knee bones and the feet. This sets the horse up for a fetlock valgus (‘toe out’), as can be seen in the left foreleg in this image.

Also a conformational trait, this kind of leg is frequently seen in Quarter Horses. A wide chest and narrow lower limbs can also contribute to a postural rotation of the foreleg.

Similar rotation in the lower forelimb can also be an acquired ALD, if a young horse has to change its weight bearing for a long time, due to (say) an injury in the diagonally opposite hind limb.

From certain angles, this rotation can look like a carpal valgus. Always check from different angles to be sure.

Key point: face of cannon and knee appear rotated outwards; pastern and toe often angled outwards, medial splints more likely; medial hoof wears faster.

 

 

Other resources

[1] Redden, RF. How to Evaluate Foot Flight and Leg Alignment
AAEP PROCEEDINGS, Vol. 57, 2011, p.407

[2] https://www.rossdales.com/assets/files/Angular-limb-deformities-in-foals.pdf

[3] O’Grady, SE, Routine Trimming and Therapeutic Farriery in Foals, Th Veterinary Clinics of North America, Equine Practice, 2017

Filed Under: Bodywork, Foals Tagged With: angular limb deformities, angular limb deviations, carpal valgus, crooked legs, foal legs, foal limbs, GA, tarsal valgus

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