By Popular Demand: Here’s How You X-Ray for the C6-C7 Malformation

News about the malformation of the C6 and C7 vertebrae has understandably raised a lot of concern. There are major implications for both buyers and breeders of TB and TB-derived breed horses, as outlined in the original article, All You Need to Know About the Hidden C6-C7 Malformation That’s Bringing Horses Down. In response, Sharon May-Davis has very kindly provided us with the English version of a paper she published in the Journal of Japanese Local Government Racing, outlining a preliminary protocol for radiographing this area of the neck and identifying the malformation. (Yes, a single racing authority has taken this issue on board!)

So without further ado, here is the paper in its entirety, the only adaptations being the positioning of images to better fit this site’s blog format.

 © All text copyright of the published authors. 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!

 

Preliminary Radiographic Protocols for Identifying Congenital Malformations of the Caudal Cervical Vertebrae

Authors: May-Davis SER, Minowa F, Monoe S

 

Abstract

In 2014, a published study based on dissections and skeletal examinations noted that 19:50 Thoroughbred horses had a congenital malformation of the 6th cervical vertebra (C6). In addition, it was found that in those 19 Thoroughbred horses expressing a congenital malformation of C6, 9 displayed a concurrent congenital alformation of the 7th cervical vertebra (C7). In this study, 3 Thoroughbred horses and 1 Thoroughbred type were clinically examined; 3 were radiographed for limb abnormalities and 2:3 radiographed for the congenital malformation of C6 and C7 prior to euthanasia. Upon dissection, 3:4 expressed a congenital malformation of C6 with 2:3 displaying a concurrent CM of C7. These 2 horses were positively radiographed for the CM of C6 and C7 prior to dissection. The radiographs of C6 were taken in direct lateral orientation with 0 degree of elevation and revealed the absence of the caudal ventral tubercle (CVT) of C6. Re-positioning the horse’s forelimbs caudally with an outstretched neck, C7 was radiographed at a 30° oblique lateral angle in a cranial to caudal direction with 0 degree of elevation; the transverse process of C5 remained cranial to the beam. The caudal aspect of the plate was positioned medial the Cranial deep pectoral and rotated vertically to expand the field of view of the cervical vertebrae, whilst remaining perpendicular to the beam

 

Introduction

In recent times, 3 Australian studies reported congenital malformations of C6, C7, the 1st sternal rib, along with their associative soft tissue structures. Furthermore, it was noted that these congenital malformations were predominantly breed related and more specifically, to Thoroughbred horses or derivatives thereof. In addition, reports of forelimb proprioceptive dysfunction, neurological impediment and gait deficits were concurrently noted (May-Davis [a,b], May-Davis and Walker). The congenital malformations of C6 appeared as either a left or right unilateral absence of the caudal ventral tubercle (CVT) or as a bilateral absence of the CVT (Figure 1).

 

Left: Normal. Centre: Absent right CVT. Right: Bilaterally absent CVT

Figure 1. View of the ventral aspect of C6, cranial aspect top. Photo credit: Sharon May-Davis

 

The congenital malformation of C7 appeared with either a fully transposed CVT from C6 onto the ventral surface of C7 or a partial transposition of the CVT from C6 onto the ventral surface of C7 (Figure 2) (May-Davis [a]).

 

Left: Normal. Centre: Transposed right CVT. Right: Bilaterally transposed CVT

Figure 2. View of the ventral aspect of C7, cranial aspect top. Photo credit: Sharon May-Davis

 

The congenital malformation of the 1st sternal rib appeared in multiple presentations with gross anatomic variations including; an absent 1st sternal rib; bifid Tuberculum costae (Figure 3); bifid Sternochondral articulation onto the sternum; flared shaft; normal 1st sternal rib inserting onto the cranial branch of a bifid Sternochondral articulating 2nd sternal rib; straight costal shaft and an articulating rudimentary Tuberculum costae with a ligamentous extension replacing the bony shaft and attaching to a rudimentary Sternochondral articulation onto the sternum (May-Davis [b]).

Figure 3. Left costal bifid Tuberculum costae. Photo credit: Sharon May-Davis

Associative soft tissue structures varied according to the presentation of the congenital malformation with the most noted being, the Longus colli muscle, Scalene muscles and neural vessels such as the Phrenic nerve and Brachial plexus (May-Davis [b], May-Davis and Walker).

The congenital malformations noted in these 3 studies were determined via dissection and skeletal examination. They were based on 2 specific skeletal variations in C6 and C7 plus any variation to normal of the 1st sternal rib.

The congenital malformations could appear in C6 as a singular expression with no other anomalies, however, the congenital malformation of C7 only occurred when the CVT was absent on C6. The congenital malformations of the 1st sternal rib only occurred in the presence of the congenital malformation of C6 and C7 (Table 1) (May-Davis [b]).

With this in mind, the premise that if a congenital malformation exists in C6 then there is a 50% chance that transposition will occur on C7. In this format, it would stand to reason that there could also be an anomalous rib. Therefore, this study is designed to identify the absent CVT on C6 and investigate its transposition onto C7.

 

Table 1. Noted observations of 151 horses of mixed gender aged between 0 (stillborn) and 30, exhibiting a congenital malformation of C6, C7 and the 1st sternal rib.

 

Materials and Methods

After evaluation and clinical examination, the 2 horses (1 Thoroughbred and 1 Thoroughbred type) were restrained in cross ties. Detomidine Hydrochloride (Detomovet CEVA Animal Health Pty Ltd) was administered via left jugular vein venepuncture. The dosage was determined by the clinician’s experience and in consideration of the individual’s current health status.

The radiographs were obtained by utilising a Porta 100 HF High Frequency portable x-ray unit (7.8kgs). The kV range was 40-100kV with an mA range of 20-30 mA and a mAs range of 0.3 – 20 mAs. The images were captured on a wireless Rayence 1012WCA Medical Image processing unit (26cm x 32.5cm) and computerised with Vetview Digital Diagnostic Imaging software.

The radiographic angles were obtained with the horse’s neck in full extension and the forelimbs behind the vertical in standing position. With the clinician standing with the x-ray unit on the left side of the neck and the plate positioned on the right side of the neck, the distance between the x-ray unit and plate was 80cms. The x-ray unit and plate remained lateral to the cervical vertebrae determined by the transverse processes of C5.

The first view is a direct lateral at 90 degrees, with 0 degree of elevation whilst maintaining the transverse process of C5 to the left of the beam. 

Remaining lateral to the cervical vertebrae with a 0 degree of elevation, the second view is taken with the x-ray unit positioned at a 30° oblique lateral angle in a cranial to caudal direction with the transverse process of C5 cranial to the beam. The caudal aspect of the plate is positioned medial the Cranial deep pectoral and rotated vertically to expand the field of view of the cervical vertebrae, whilst remaining perpendicular to the beam.

Upon the radiographic evaluation of C6, radiographs of C7 are obtained. The 4 horses were then euthanized and dissected so to verify the radiographic findings. Only those pertaining to the congenital malformation of C6 and C7 are reported in this study.

 

Results

Figure 4. A compressed trachea (white arrow) in Thoroughbred No. 2 at C6 / C7. Photo credit: Sharon May-Davis

Upon euthanasia of the 4 horses, Thoroughbred No.1 was normal. Thoroughbred No.2 presented with an absent CVT in C6 and trachea compression (Figure 4).

Thoroughbred No. 3, presented with a C6 and C7 congenital malformation and a malformed 1st sternal rib. The Thoroughbred type also presented with a congenital malformation of C6 and C7 (Table 2).

 

 

Table 2. Noted observations via dissection of the congenital malformation of C6, C7 and the 1st sternal rib.

 

Left: Radiographic view of C6. Centre: The white line denotes a normal CVT. Right: The white denotes an absent CVT.

Figure 5. The radiographic lateral view of C6 depicting a unilaterally absent CVT in C6. Image credit: Sharon May-Davis

 

Thoroughbred No. 3 C7 radiograph (Figure 6) clearly presents the observer with a transposition of the CVT from C6 onto the ventral surface of C7, furthermore it denotes a reciprocal deviation in the trachea at the point of this transposition.

 

Left: Radiographic view of C7. Centre: The white line denotes the unilateral transposition of the CVT from C6 onto the ventral surface of C7. Right: The white line denotes the deviation in the trachea.

Figure 6. The radiographic view of C7 depicting a unilaterally transposition of the CVT from C6. Image credit: Sharon May-Davis

 

The Thoroughbred type (Figure 7) exhibits the absent CVT in C6. The radiograph clearly indicates an absent CVT that is unilateral in its presentation.

 

Left: Radiographic view of C6. Centre: The white line denotes a normal CVT. Right: The white denotes an absent CVT.

Figure 7. The radiographic lateral view of C6 depicting a unilaterally absent CVT in C6. Photo credit: Sharon May-Davis.

 

The Thoroughbred type C7 radiograph (Figure 8) clearly presents the observer with a transposition of the CVT from C6 onto the ventral surface of C7, furthermore it denotes a reciprocal deviation in the trachea at the point of this transposition.

 

Left: Radiographic view of C7. Centre: The white line denotes the unilateral transposition of the CVT from C6 onto the ventral surface of C7. Right: The white line denotes the deviation in the trachea.

Figure 8. The radiographic view of C7 depicting a unilaterally transposition of the CVT from C6. Photo credit: Sharon May-Davis.

 

Figure 9. Right: Absent CVT on C6 (white arrow) and transposed CVT from C6 onto the ventral surface of C7. Photo credit: Sharon May-Davis

Upon dissection, the Thoroughbred type displayed identical congenital malformations of C6 and C7 as depicted in the radiographs (Figure 9).

 

 

 

 

 

Discussion

This study was conducted with the view to obtain specific radiographic evidence of the congenital malformation of C6 and C7. Radiographic views of the 1st sternal rib were not possible due to thick and dense musculature in the region. The views obtained of C6 and C7 with exact radiographic angles proved that this region can be radiographed with precision so that the practitioner can make a clear diagnosis should a horse present with a neurological deficit, as previously published (May-Davis

[a, b], May-Davis and Walker]). Furthermore, the asymmetry of the cervical vertebra could exacerbate arthritis in the articular process joints as previously noted (May-Davis [a]). In addition, the incidental finding of the compression of the trachea is an important factor to consider when Thoroughbred racehorses present with compromised airways. An explanation for this occurring is that the Longus colli muscle hypertrophies in support of the weakened structures and due to its proximity to the Trachea, it impinges upon its dorsal surface. This impingement is further exacerbated by the ventral projection from C7 of the transposed CVT from C6.

Since the first publication in 2014, retrospective studies were conducted that added another dimension to the current research. Italian and American studies noted that Warmbloods, Quarter Horses and Arabs were also afflicted with this condition (Santinelli et. al 2016 and DeRouen et.al 2016). It is significant to note that these breeds present the majority of the ridden horse population in Japan extending from Racing, Showjumping, Dressage to Eventing and Endurance. However, a specific Dutch Warmblood study was conducted with fresh cadaver’s that were portioned and CT scanned (Veraa et.al 2016), this also included Oldenburg horses. The congenital malformation of C6 and C7 was present in both breeds with a noted malformed 1st sternal rib in a Dutch Warmblood. Combined percentages of these 3 studies in conjunction with the 3 Australian studies and the current study has the congenital malformation of C6 at; Warmbloods 30%, Quarter Horses 16% and Thoroughbred horses over 40%. 

Aside from the Arabian who is an ancestor to the Thoroughbred, the Warmblood breeds and Quarter Horses all have Thoroughbred lineage in the back line of their breeding. Thus, implying that this condition is heritable as noted by May-Davis [b] and more systemic than just one breed. With this in mind, all critical events should be assessed with the knowledge that a potential congenital malformation could exist in C6, C7 and the 1st sternal rib, as previously noted. With the largest population of horses in Japan being Thoroughbreds, it would be a recommendation to note the studies of several countries including Japan and the severity in percentage of this systemic congenital malformation. Especially in relation to Thoroughbred’ racehorses racing and cornering at speed.

 

Conclusion

This study showed that of the 4 horses investigated, 3:4 horses displayed a CM of C6, 2:3 displayed the congenital malformation in C6 and C7, and 1:2 a congenital malformation of the 1st sternal rib. Even with a small sample of Thoroughbreds, studies from other countries must be measured and it would therefore be a recommendation to radiograph for this condition in the caudal cervical vertebrae in a pre-purchase examination. The purpose of which would be to eliminate this condition so that riders and handlers are not put at risk.

 

Author contributions

Sharon May-Davis, Fumiko Minowa and Sadae Monoe wrote and reviewed this article.

 

Conflict of Interest

The authors have no conflict of interest in the preparation or presentation of this original research article.

 

Acknowledgement

The author wishes to thank Christine Gee for her professional advice on the manuscript. The Nippon Veterinary and Life Sciences University for the use of their facilities and to those authors / editors/ publishers of those articles, journals and books cited in this manuscript.

 

References

Derouen A, Spriet M, Aleman M. Prevalance of anatomical of the sixth cervical vertebra and association with vertebral canal stenosis and articular process osteoarthritis in the horse. Vet Radiol Ultrasound, Vol. 00, 2016, pp 1–5.

May-Davis SER. The Occurrence of a Congenital Malformation in the Sixth and Seventh Cervical Vertebrae Predominantly Observed in Thoroughbred Horses. J Equine Vet Sc 2014; 34:1313-17.

May-Davis SER. The Congenital Malformation of the 1st Sternal Rib. J Equine Vet Sc 2014; 34:1313-17.

May-Davis SER, Walker C. Variations and implications of the gross morphology in the Longus colli muscle in Thoroughbred and Thoroughbred derivative horses presenting with a congenital malformation of the sixth and seventh cervical vertebrae. J Equine Vet Sc 2015; 35:560-8.

Santinelli I, Beccati F, Pepe M. Anatomical variation of the spinous and transverse processes in the caudal cervical vertebrae and the first thoracic vertebra in horses. EVJ 48 (2016) 45–49.

Veraa S, Bergmann W, van den Belt A-J, Wijnberg I, Back W. Ex vivo computed tomographic evaluation of morphology variations in equine cervical vertebrae. Vet Radiol Ultrasound, Vol. 00, 1–7.

 

 

 

All You Need to Know About the Hidden C6-C7 Malformation That’s Bringing Horses Down

What if you were to learn that your horse is living with a hidden malformation? A skeletal abnormality that could be affecting it every day, changing the way it moves, creating a string of other physical problems, and possibly underlying the hard-to-pinpoint problems you’ve been noticing for months or even years ?

And that might even be causing a level of inherent instability that could be putting the rider in danger?

Sadly, this isn’t a hypothetical question. Instead it’s a reality that is only now being slowly uncovered.

And like the proverbial stone rolling down a mountain, the issue is gathering momentum as the equine industry, owners, breeders and researchers learn about it.

  • It’s a skeletal malformation and it can’t be corrected.
  • It’s congenital, ie inherited, so is present from birth.
  • It has been in some lines of TBs for hundreds of years.
  • It creates biomechanical issues due to asymmetry and lack of anchor points for key muscles.
  • At its worst, it can contribute to neurological issues such as Wobbler syndrome.
  • Some horses are so unstable, they are more prone to falling (not good news for jockeys).
  • It can cause constant pain and associated behavioural changes.
  • It’s primarily found in Thoroughbreds, Thoroughbred crosses and Warmbloods, but has also been identified in European breeds, Quarter Horses, Arabs and Australian Stock Horses.

 

The problem behind this is a congenital malformation of the C6 and C7 cervical vertebrae (ie, base of neck) – and it’s pretty nasty.

I’ve written about the work of Sharon May-Davis on this blog before and here I’m going to do so again. Through her many dissections per year, gross anatomist Sharon has become the first person to comprehensively document and quantify this problem. 

In doing so, and publishing her findings in peer-reviewed journals, she has triggered a minor research avalanche as others take up the subject.

 

Those of us fortunate to attend Sharon’s many equine dissections in Australia, New Zealand, Japan, and Europe have been learning about this for some time. For bodyworkers and hoof trimmers, it has dramatically changed our work. I believe I’ve worked on several horses with this problem, including an eventing horse, a dressage prospect, and a TB intended for a child.

It is, not to put too fine a point on it, an extremely serious problem that is in some cases grave for the horse concerned and can potentially cause injury or loss of life for the rider.

 

The following is an amended version of an article that I wrote for the Winter 2017 edition of Equine News, a NSW, Australia print magazine that sponsored one of Sharon’s series of public lectures on this issue.

Questions, thoughts or comments? Join us at The Horse’s Back Facebook Group. 

 

A hidden problem: this OTTB had the C6-C7 malformation but presented few outward signs.

 

Twenty years of research

Sharon May-Davis’s path with this research began some 20 years ago. In February 1996, a Thoroughbred called Presley came down unimpeded in a race in Grafton, NSW, fracturing his pelvis, a hock bone, and right front fetlock.

Three years later, Sharon examined his bones, and saw something strange in his last two cervical vertebrae and his first ribs.

Fast forward to 2014, when Sharon published the first of her four peer-reviewed papers in the Journal of Equine Veterinary Science, concerning a congenital malformation in the sixth and seventh cervical (neck) vertebrae.

Although the problem had been mentioned briefly in papers, this was the first time that a researcher had accurately described and quantified the problem in its various forms.

Sharon’s unique perspective, gained as an anatomist who dissects between 15 and 20 horses per year, had certainly placed her in a position to do so.

 

The horse’s seven cervical vertebrae – made simple

Horses have seven vertebrae in their necks, labelled C1 to C7. Of these, four have unique shapes. Most horse people are familiar with C1, the first vertebrae known as the atlas, as it can be both seen and felt by hand with its distinctive ‘wing’ at the top of the neck.

Cervical vertebrae from C1 (top) to C7 (bottom), view from above (L) and below (R).

Almost as well-known is C2, the second vertebrae, known as the axis.

Both atlas and axis have unique shapes for a special reason: they support the heavy skull and anchor the muscles that control the head’s movement.

Heading down the neck, C3, C4 and C5 are broadly similar in shape, with each being a bit shorter and blockier than the one above.

However, C6 and C7 are both slightly different on the ventral (lower) side, for here they provide insertion points for muscles arising from the chest.

 

  • C6 has transverse processes (the protrusions extending outwards) that are different to those of neighbouring bones, with two distinctive ridges running the vertebrae’s length. C6 also has two large transverse foramen, the openings that the arteries pass through.
  • C7 is the shortest and squattest cervical vertebrae of all. Its transverse processes are shorter, while there are also two facets that articulate with the first ribs. C7 has no transverse foramen.

 

At least, that’s how the vertebrae should be in a normal horse.

 

So, what is wrong with the malformed C6 and C7 vertebrae?

In certain horses, these last two vertebrae are rather different, being malformed.

Sharon has identified the manifestations of this problem as a congenital (inherited) malformation affecting some Thoroughbred horses, and horses with Thoroughbred blood in their ancestry.

In C6, there is a problem with the two ridges of the transverse processes, as one or both can be partially absent.

When both are partially missing, it is common for one or two ridges (ie, parts of the transverse processes) to appear on C7 instead.

Also, the articular processes (the oval surfaces on the upper side, where each vertebrae links to its neighbours) can be radically different sizes. There can also be an additional arterial foramen or two.

The level of asymmetry can be radical.

 

 

The secondary problems this malformation causes

Being at the base of the neck, the asymmetry of C6 and C7 can cause alignment problems all the way up the vertebral column, leading to osteoarthritis of the articular facets.

It can also contribute to Wobbler Syndrome (Cervical Vertebral Stenotic Myelopathy), due to narrowing and/or malalignment of the vertebral foramen/canal, the opening through which the spinal cord passes. Not all Wobbler cases have this particular malformation, though.

A further problem is that the lower part of the longus colli muscle, which is involved in flexing the neck, would normally insert on the transverse processes of C6 and C7. When these processes are malformed, the normal insertions are not possible.

This means there is a serious symmetry problem in the junction of the thorax and neck, which can have a deeper effect on the horse’s neurology and proprioception, as well as respiration.

 

Asymmetry and narrowed vertebral foramen (canal) contribute to DJD and Wobbler Syndrome.

 

In a few cases, horses with both the C6 and C7 problem also have malformations of the first sternal rib, on one or both sides. This can cause problems beneath the scapular and further issues with muscular attachments.

Associated stability problems can have far-reaching consequences for the horse, not to mention some serious safety issues for the rider. The safety issue can’t be stated often enough.

(Add to this the fact that the horse’s nuchal ligament lamellar does not attach to C6 and C7, and often only feebly to C5, then you can see that this is a high level of instability in a critical area. Read more about Sharon’s findings on the nuchal ligament here – How the Anatomy Books Unintentionally Fail us Over the Nuchal Ligament.) 

Read on for information on for signs that this problem may be present in the living horse…

 

© All text copyright of the author, Jane Clothier, www.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!

 

Why isn’t the C6-C7 problem more widely known ?

Why hasn’t this problem been noticed in regular veterinary interventions?

The answer is quite simple. While neurological issues may have been diagnosed, the exact cause has often remained hidden. 

Both Thoroughbred horses and Warmbloods are known to have higher incidences of Wobbler Syndrome than other breeds, and while this is certainly not always due to C6-C7 malformation, the malformation has been found in some when dissected.

For example, the following dissection image appears in a veterinary account of large animal spinal cord diseases. It clearly shows a malformed C7 vertebrae, very similar to the one in the above image, but without giving any further categorisation.

The difficulty lies in the deep location of the lower cervical vertebrae. While normal radiographs can show all or some of C6, they are unable to penetrate the deeper tissues beneath the shoulder to image C7.

 

Photo from another online article: the familiar asymmetry of a malformed C7 is clearly visible in a dissected set of vertebrae.  (c) veteriankey.com (click image to access full article.)

 

Nevertheless, the malformation can be identified in radiographs of C6, once you know where to look.

Since Sharon’s first paper appeared, the School of Veterinary Medicine, University of California, Davis, has reviewed its history of radiographs from horses with Wobbler Syndrome.

Researchers found that 24 cases out of 100 (close to 25%) showed malformation of one or both C6 transverse processes. This study also clarified how to identify the problem on standard radiographs of C6.

In another study, the Faculty of Veterinary Medicine, Utrecht University, completed CT scans on horses’ necks and found the various forms of the malformation in 26 horses out of 78 (33%). Unlike radiographs, the CT scans enabled identification of the C7 and first rib issues, although of course this imaging was conducted post mortem.

 

Is this rare, or are many horses affected?

While the problem has been identified primarily in TBs, it affects most breeds with TB blood in the ancestry to some degree.

Sharon May-Davis reports that to date, published, peer-reviewed journal papers have tallied 136 out of 471 horses as exhibiting congenital malformation of C6.

These have been in a range of breeds including Thoroughbreds (39%), Thoroughbred crosses (27%), Warmbloods and European breeds (30%), Quarter Horses (11%), and Arabs (11%). Standardbreds have also shown the problem, although the numbers included in studies are very small.

A common question is whether it’s known which TB lines predominantly carry this problem. The answer is: Yes. However, it is now so disseminated amongst the modern equine population beyond TBs, that it is of little help to identify them.

 

“Eight Belles… might have been genetically predisposed to breaking down.” 

Exploring the views of a TB lineage expert, this American article from 2009 asks why certain TB lines were prone to breaking down on the track – Eight Belles Breakdown: A Predictable Tragedy

 

It must be remembered that these horses are those already brought to veterinary attention and/or euthanized for a related or unrelated reason, so the percentages may be higher than those for the general horse population. At the same time, the malformation might have played a major part in the horses’ decline, due to the many locomotory and postural problems it can lead to.

 Questions, thoughts or comments? Join us at The Horse’s Back Facebook Group. 

 

‘Gift Horse’, the Trafalgar Square sculpture by Hans Haacke, displayed the malformation, presumably having been modelled on a modern-day skeleton. The George Stubbs anatomical drawing on which it was styled did not. Image (c) bowlofchalk.net

 

How do we identify these horses in life?

It’s all very well looking at these bones post mortem, you might say. Yet how can I tell if my horse has this problem? Or a horse that I might want to buy?

Some answers are forthcoming. As Sharon has frequently assessed horses before dissecting them – usually from video – she has been able to observe that many of these horses lack stability. (Indeed, in many cases, it is this very instability has directly led to the horse being euthanized, and ending up on the dissection table.)

As her research has progressed, she has also been able to identify many biomechanical and locomotion traits that make these horses ‘suspicious’ or at least ‘of interest’. Unsurprisingly, these problems have been particularly noticeable in horses with both a malformed C6 and C7.

For owners and equine professionals, here are some signs that can raise initial suspicions. All can also be caused by other problems, so a group of signs is more common than an individual indication.

  • Some of these horses have a problem with standing square in front, and will always keep one foot further forward. This can persist despite all attempts to improve the horse’s body and to train the horse to halt squarely.
  • Horses with the more serious malformations will often stand base-wide. Such horses can become very unbalanced on uneven ground, and sometimes in work. They easily become unbalanced when a hoof practitioner works on a forefoot. 

 

A bilateral C6 – unilateral C7 horse showing a toe-out stance and hoof distortion. The ventral part of the transverse process was transposed onto the left side of C7.

 

  • With such asymmetry in the skeletal structure, these horses have serious lateral flexion issues that can’t be overcome. When required to elevate the forehand, many will experience difficulties, due to the absence of correctly inserted musculature and incorrect articulation through the joints of the lower neck. 

 

The horse may have one very prominent, widely positioned scapula.

 

  • A high level of asymmetry may be seen in the shoulders, with one scapula sometimes positioned very wide, with no improvement after chiro, osteopathy or bodywork. This is particularly so with the C6-C7 problem and associated first sternal rib abnormalities.
  • The ventral aspect of the neck may show some scoliosis.

    There may be scoliosis along the entire spine.

  • There may be an obvious scoliosis to the underside of the neck.
  • The problem may lead to heavily asymmetric loading of the forefeet, so may be accompanied by a severe high foot/low foot issue (this is not in itself a sign of the C6-C7 problem).

 

 

 

 

 

If you suspect your horse has the C6-C7 issue

First, note that many horses do just fine with a C6 problem. It is those with the bilateral C6 and unilateral/bilateral C7 issue that tend to show the more worrying problems.

If your horse is showing ongoing signs of instability, it’s important to seek veterinary advice, so that neurological issues can be ruled out. (As this a recently recognised problem, it may be worth printing out the abstracts from the journal articles listed at the end of this page and handing them over.)

If the more severe malformations are identified by radiograph, it is important to remember that in some cases this can cause discomfort and pain to the horse, and it is not going to improve over time. 

Since this article was published, Sharon has allowed me to publish her paper with a preliminary protocol for radioagraphing for this issue. Read it here: By Popular Demand: Here’s How You X-Ray for the C6-C7 Malformation.

On the contrary, the cervical vertebrae of some older horses with the C6 and C7 malformations often display advanced osteoarthritis of the articular processes, as shown in the header image of a 19-year-old Thoroughbred’s malformed C7.

Questions, thoughts or comments? Join us at The Horse’s Back Facebook Group. 

 

Where does this knowledge take us?

At the moment, that question is wide open. The findings published by Sharon May-Davis have triggered ongoing research on an international level. There are certainly ramifications for breeders in more than one equine sporting industry.

Connections have been made with a number of falls on the racetrack that have caused injury, and worse, to both horse and jockey, as well as other runners. Similar things can be said for the sport of eventing, where unforced errors can have equally catastrophic effects.

It is entirely possible that at higher levels, pre-purchase examination radiographs will come to include a check on C6. While it’s not possible to radiograph the deeply positioned C7, we do at least know that this will only be present if the C6 anomaly exists.

Vets in some countries are proving faster at picking this up than others. While papers are being published, it clearly takes some time for information to filter down.

And until more is known, this problem is being unknowingly propagated every breeding season.

Of course, many horses harbouring the milder manifestations of this problem at C6 level are functioning very well. All horse owners can do is be aware that this issue exists, make use of this information if a problem arises, and await further research findings.

 

Since this article was published, Sharon has allowed me to publish her paper with a preliminary protocol for radioagraphing for this issue. Read it here: By Popular Demand: Here’s How You X-Ray for the C6-C7 Malformation.

© All text copyright of the author, Jane Clothier, www.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!

 

Sharon May-Davis’s research includes the rarely documented arthritis affecting the elbow joint of ridden and driven horses – Revealed: the Common Equine Arthritis You Won’t Read About in Textbooks.

Plus, read about the effects of hard race training on Thoroughbreds – Buying an Ex-Racehorse: Can You Spot the Major Physical Issues? – and advice from a seasoned trainer on rehabbing your horse once it’s arrived at your stable – 8 Golden Rules for Helping Your Thoroughbred Get Right Off the Track.

 

Literature on the malformation

 

Peer reviewed journal articles on the C6-C7 and related first sternal rib issues.

 

5 Ways Your Seat Can Screw Up Your Horse Without You Even Noticing


Something that saddle fitters know but that’s often the last thing riders think of: it’s the riding position as much as the saddle fit that’s affecting their horse’s back and movement. In this Guest Post, ‘Classical Seat’ trainer Heather Moffett looks at how the rider’s seat can make movement harder for the horse.

 

We all keep hearing about ‘connection’.  It’s a current buzzword and usually means connecting with your horse on the ground, either through loose or in-hand work.

Many riders assume this will enable them to achieve the same connection once mounted.

There is nothing wrong with that. However, they often then wonder why they lose that connection – sometimes literally, complete with the saddle(!) – once they start riding. The fact is that they are, in ignorant bliss, impeding the horse!

The UK’s Heather Moffett has over 40 years’ instruction experience. Chiefly following the French school of classical equitation, which focuses on dressage as an art form rather than competition, she is best known as an authority on the Classical Seat. Recently, she launched The Online Riding School, a library of videos suitable for everyone from complete beginners to advanced riders – visit now to benefit from the introductory offers.

Questions, thoughts or comments? Join us at The Horse’s Back Facebook Group. 

 

The Disconnected Seat

If the rider is out of sync with the horse’s movement, the flow and harmony will always be disrupted as the horse struggles to balance the rider as well as himself.

Or, he endures the discomfort of a rider sitting like a lump of lead, driving with the seat against his sensitive back, or bouncing stiffly in the saddle.

The horse has only one way to show his discomfort or pain, as he is mute, and that is by behaviour that is then construed as ‘misbehaviour’.

I often ask riders who kick and hit their horses if they would do the same to their dog. The dog is able to cry out in pain. The horse cannot, and it is his muteness, throughout history, that has led to his downfall and still does to this day.

 

What Gets My Goat is This

I’ve been a specialist trainer/teacher of the Classical seat for 46 years. In that time, there has been little interest in increasing knowledge of the seat and refinement of the aids.

So many teachers and trainers say that it is necessary to ignore imperfections in the seat until “the horse is going well”. Then they wonder why the horse never progresses, or why force must be resorted to, in order to make the horse submit!

Yes, there is that word submit (or submission) that’s a requirement in a dressage test.

My own teachers soon found that it worked far better to encourage my cooperation in school rather than forcing me into submission! And a horse is no different.

I would like to see the word submission in tests replaced with willing cooperation.

How different would the expression be on many a horse’s face, if he were trained as a partner, and not as an adversary?

 

So, are you screwing up your horse with your seat, without even noticing? Here are the 5 top points I’d like you to think about.

 

1. Saddle Fit Woes (Yes, Again)

Poor saddle fit can cause the seat to tip back.

No surprises for this one. Saddle fit is probably the most obvious thing that needs to be right, but many saddles are a long way from perfect. That’s true even in my home of the UK, where saddles are most often professionally fitted.

But, what amazes me is the number of saddles I see with clients coming to me for lessons that have faults that make it damn near impossible for the rider to sit either straight or in balance!

Here are the worst offenders.

The saddle is too narrow. This is still one of the most common faults – it pinches the horse and tips the rider’s pelvis backward, aiding a chair seat rather than the ear/shoulder/hip/heel line which is the only position of balance.

Try walking with your butt stuck out behind you and knees up, as though sitting on a chair! It’s hard enough to even remain upright! Your weight will be over the cantle region, making it difficult for the horse to lift and round his back, and causing him to go hollow.

Stirrup bars are, almost without exception, even on many dressage saddles, too far forwards. This is why the rider is constantly being nagged by instructors to “get that lower leg back”!

I do wonder why instructors and even top dressage trainers, never seem to notice that all of their students are not anatomically challenged and there might just be something wrong with the saddle design and balance!! (Don’t get me started!!)

 


2. An Insecure Seat
Sucks (for Both Horse and Rider)

7yo Oldenburg x Irish Sport Horse. 1st day to 2nd day of HM course.

Here’s what I mean by insecure. Riders are not taught to absorb and sync with the horse’s movement.

We hear:

“Sit deeper!”

“Relax your back!”

“Go with the movement!”

“Follow the horse’s movement!”

Well, usually if you are following something you are behind it!

Is it any wonder beginners are confused and often never learn to move in sync with the horse?

If this describes you, fear not. I have had riders here on my horse movement simulator workshops who’ve been riding 10, 20 or more years, and still they have never learned to move in sync with the horse.

 

3. Saddle Seat Glue Hasn’t Been Invented Yet

Gripping the saddle blocks movement.

If you’re bouncing around, or driving with both seat bones to achieve some adhesion to the saddle, or sitting on your back pockets and collapsing the rib cage, you will be making your horse’s life more difficult.

It is so NOT rocket science to learn this!

But until teachers are trained to teach it, the situation will not improve!!

And it is not just novice riders who block their horse through incorrect adhesion to the saddle.

Look at the nodding head, flailing legs (usually with spurs attached) riders to be seen even in the Grand Prix dressage arena…

 


4. Horses Have the Low Down on Our Weight Issues…

How many times do you hear it said that a horse can feel a fly land on his back? So how much more can he feel his rider, whether good or bad?

For me, my aim – both as a rider myself and also as a trainer – is to be as little burden on the back of my horse as possible.

The horse copes with the crooked rider. Day 1 of HM course.

I aim to do this by sitting lightly, but deeply, in sync with his movement.

If the rider is crooked, possibly due to a problem with the saddle, or is asymmetric due to their own physical problem, the horse suffers.

He has to cope with this and compensate, usually by going crookedly himself.

And there’s more. The use of the rider’s body as a primary aid, is so rarely taught. Yet when utilised, it is the most invisible aid of all. Combined with the seat bones moving in sync with the horse’s back, it is the secret to an elegant harmonious seat, that appears to be doing nothing.

That’s when the horse and rider glide through all the movements as though they are one being – like a Centaur.

 

5. ‘Feel’ Begins in your Backside (I Mean It!)

Hanoverian X. 1st and 2nd day of HM course.

‘Connection’ means being able to feel, and not just when working from the ground. We all have nerve endings in our backsides – if you are taught what to feel and how to feel, it is within the grasp of any rider, even beginners.

And ‘aid’ really means ‘help’. If you learn to use aids that make biomechanical sense to the horse, they do become truly invisible as the horse becomes more and more sensitive with correct training.

BUT, if the horse hasn’t been schooled to respond to specific aids, then is it any wonder he is confused and ‘misbehaves’? It’s a bit like us lazy Brits here, shouting at foreigners in the hope they will understand English then getting annoyed when they don’t!

Your seat can genuinely aid (help) your horse. This happens when you’re taught not only the hand and leg aids, but also:

  • the weight aids for turning,
  • the seat aid for collecting and for downward transitions,
  • the precise positioning of the torso in lateral work and circles/ bends, etc.

At this point, riding becomes a whole language, which almost all horses quickly understand. Why? Because it is working with, not against, their own body.

Moving in sync with the horse allows the rider to learn ‘feel’, that term that often seems to imply that only a favoured few have the ability to learn it.

Rubbish!

 

So in closing, if you wish to have true connection with your horse, you need to:

a) Absolutely not screw up either his back or his brain,

b) Learn to ride to the best of your ability, and

c) Treat your horse as a partner and friend, and not as a tool merely to win the next rosette.

If winning happens as a by-product of good riding, even better, but if your horse is not progressing, look to your own riding and equipment before you blame your horse. Get these 5 points sorted and you’ll be well on your way to true connection with your horse!

 

 


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Meet Spinalis, the Forgotten Muscle in Saddle Fitting

Spinalis Header

It’s barely mentioned in saddle fit or anatomy books, yet  M. spinalis cevicis can hugely impact on the spinal health and movement of the horse, particularly with poor tack fit.

Meet M. spinalis cervicis et thoracis, a far more important muscle than is generally realized. As a deep muscle, it’s influential in mobilizing and stabilizing that hidden area of the spine at the base of the neck, the cervico-thoracic junction, deep between the scapulae.

 

Where to Find this Muscle

As part of the deeper musculature, M. spinalis is as hidden in books as it is in life. Usually, it’s a single entry in the index.

Spinalis StandardAt best, it has no more than a bit part in anatomical illustrations,  usually as a small triangular area at the base of the withers. This is also where we can palpate it.

The reality is quite a bit more interesting. It’s actually a muscle of three parts – dorsalis, thoracis and cervicis. These names denote its many insertions,
for it links the spinous processes of the lumbar, thoracic and cervical vertebrae.

  • Bradley_2.1Further back along the spine, it lies medially to the M. longissimus dorsi, and in fact integrates with this larger, better known muscle, attaching to the processes of the lumbar and thoracic vertebrae.
  • When it reaches the withers, it becomes more independent, attaching to the processes of the first half dozen thoracic vertebrae (T1-T6). Here, the cervical and thoracic portions overlap and integrate to share a common attachment. (The part we palpate, at the base of the withers, is the thoracic section.)
  • Heading into the neck, as M. spinalis cervicis, it attches to the last 4 or 5 cervical vertebrae (C3/C4-C7). Only the lamellar portion of the nuchal ligament runs deeper than this muscle.

Dissection 2Its integration with other muscles is complex, and its close relationship with M. longissimus dorsi partially explains why it doesn’t get much consideration as a muscle in its own right.

It is the more independent section, M. spinalis cervicis, between withers and neck, that we are interested in, although its influence is present along the entire spine.

© All text copyright of the author, Jane Clothier, www.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!

What Does Spinalis Do? 

In his 1980s’ Guide to Lameness videos, Dr. James Rooney, first director of the Gluck Equine Research Center, University of Kentucky, referred to M. spinalis as part of the suspension bridge of muscles supporting the spine (M. longissimus dorsi achoring from the lumbosacral vertebrae, M. spinalis thoracis et dorsalis from the upper thoracics). He also refers to this extensively in The Lame Horse (1988).

In fact, the suspension bridge analogy only really makes sense if M. spinalis dorsi is considered.

M. spinalis cervicis is usually credited with a role in turning the head to left to right, and raising the head.

Bradley Spinalis-1Older texts, such as Bradley’s 1922 veterinary dissection guide, Topographical Anatomy of the Horse, mention its role in stabilizing the spine.

This creates a point of interest. Given that the nuchal ligament (lamellar portion) doesn’t attach to C6 and frequently only weakly with C5 (see the findings of anatomist Sharon May-Davis, in this earlier article ), M. spinalis cervicis suddenly appears pretty important in stabilizing and lifting the base of the neck, particularly as it does so at the point of greatest lateral bending.

ETA: Having now talked to Sharon, it appears that in her dissections, she has made a finding about an association between the lamellar portion of the nuchal ligament and M. spinalis. I’ll be writing an update article on this in February. [added 3 Jan 2017]

 

Spinalis and Poor Saddle Fit

Anyone who has been involved in close examination of the horse’s back will recognize M. spinalis thoracis where it surfaces close to the skin, on either side of the withers.

When a horse has been ridden in an overly tight saddle, this small area of muscle can become pretty hypertrophic – raised and hardened. Typically, the neighbouring muscles are atrophied. When M. spinalis is palpated, the horse often gives an intense pain response, flinching down and raising the head.

GerdHeuschmanWhat often happens is this. An overtight saddle fits over the base of the withers like a clothes peg, pinching M. trapezius thoracis and  M. longissimus dorsi. However, it frequently misses M. spinalis thoracis where it surfaces, wholly or partially within the gullet space. Often, the muscle is partially affected.

It’s as if the neighbouring muscles are under lockdown. Free movement of the shoulder is restricted and the horse’s ability to bear weight efficiently while moving is impeded. In response to the surrounding restriction and its own limitation, this muscle starts to overwork.

Result? The horse, which was probably already moving with an incorrect posture, hollows its back even further, shortening the neck and raising its head.  As this becomes even more of a biomechanical necessity, all the muscles work even harder to maintain this ability to move, despite the compromised biomechanics.

Working harder and compensating for its neighbours, M. spinalis becomes hypertrophic. It is doing what it was designed to do, but it’s now overdoing it and failing to release. We now have a rather nasty vicious circle.

 

Spinalis photo

 

 

Here, M. spinalis thoracis stands out due to atrophy of the surrounding musculature. In this TB, a clearly audible adjustment occurred in the C4-C5 area after M. spinalis was addressed. 

 

 

Vicious CircleThe Inverted Posture and Asymmetry

Of course, saddle fit is not the only cause of an inverted posture. However, any horse that holds its head and neck high for natural or unnatural reasons is more vulnerable to saddle fit issues, thus starting a cascade effect of problems.

Are there further effects of this hypertrophy? Consider the connections.

  • When saddles are too tight, they’re often tighter on one side than the other. This can be due to existing asymmetry in the horse, such as uneven shoulders, uneven hindquarters, scoliosis, etc.
  • On the side with greater restriction, the muscle becomes more more hypertrophic.
  • With its attachment to the spinous processes of the lower cervical vertebrae, there is an unequal muscular tension affecting the spine.
  • Without inherent stability, the neck and head are constantly being pulled more to one side than the other, with the lower curve of the spine also affected.
  • Base of neck asymmetry affects the rest of the spine in both directions and compromises the horses ability to work with straightness or elevation.
  • There is also asymmetric loading into the forefeet.
  • We haven’t even started looking at neurological effects…

This isn’t speculation. I have seen this pattern in horses I’ve worked on, many times over.

 

 

 

 

 

So, How Do We Help?

In working with saddle fit problems, the saddle refit may be enough to help the horse, if the riding is appropriate to restoring correct carriage and movement. Obviously, the horse’s musculoskeletal system is complex and no muscle can be considered in isolation. As other muscles are addressed through therapeutic training approaches, with correct lateral and vertical flexion achieved, M. spinalis will be lengthened along with the surrounding musculature.

I hold with a restorative approach:

  1. Refit the saddle, preferably with the help of a trained professional,
  2. Remedial bodywork, to support recovery from the physical damage,
  3. Rest the horse, to enable healing of damaged tissue and lowering of inflammation, and
  4. Rehabilitate the horse, through the appropriate correct training that elevates the upper thoracics while improving lateral mobility.

This is particularly important where saddle fit has been a major contributor to the problem. I have frequently found that in these cases,correction will take longer to achieve, as the debilitating effects of poor saddle fit (especially long-standing issues) can long outlast the change to a new, better-fitting saddle. In bodywork terms, the hypertrophic M. spinalis cervicis is often the last affected muscle to let go.

It’s as if M. spinalis cervicis is the emergency worker who will not leave until everyone else is safe.

 

Bodywork Notes

I am fortunate, in that my modalities enable the gentle release of joints through a non-invasive, neuromuscular approach.  The responses I’ve had from horses when M. spinalis cervicis et thoracis has been addressed in isolation have been hugely informative.


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Appendix: Spinalis in the Textbooks

I’m going to add Spinalis references to this post on a regular basis, as I come across them. It’s interesting to see how much, or how little, the muscle is referenced in various textbooks.

 

Equine Back Pathology

This image, from Equine Back Pathology, ed. F Henson 2009, shows acute atrophy of M. longissimus dorsi due to neurological damage. It’s still possible to see the raised attachment/origin of M. spinalis cervicis et thoracis – the highlighting is mine. Spinalis does not appear in the book’s index. (added 23 Dec 2016)

 

nuchal and spinousI have also altered this image, in order to show M. spinalis cervicis more clearly. This is Fig 2.16 from Colour Atlas of Veterinary Anatomy Vol 2, The Horse, R Ashdown and S Done. Spinalis cervicis is within the bounded area and it’s possible to see how it overlies the lamellar part of the nuchal ligament, lamellar portion. (added 23 Dec 2016)

 

S&GThe muscle is tinted green in this image from Sisson and Grossman’s The Anatomy of Domestic Animals, Volume 1, fifth edition 1975.  Here, it is labelled Spinalis et semi-spinalis cervicis. This anatomical figure is credited to an earlier text, Ellenberger and Baum, 1908. (added 23 Dec 2016)

 

 

 

James Roony dedicates two pages to the ‘suspension bridge’ theory of the vertebral column in The Lame Horse (1988). His interest is in M. spinalis dorsii section of the muscle and its effect behind the withers, in conjunction with M. longissimus dorsii. (added 4 Jan 2017)

 

 

 

 

 

Schleese diagramMaster Saddler Jochen Schleese refers to M. spinalis dorsi and its function in stabilizing the withers in Suffering in Silence, his passionate book about saddle fitting from 2014. “This muscle area is especially prone to significant development – especially with jumpers – because it is continually contracted to accommodate the shock of landing”. The surface area of the muscle is indicated in the anatomical figure, reproduced here. (added 23 Dec 2016)

 

 

 

 

In his seminal text addressing issues of modern dressage training, Tug of War, 2007, Gerd Heuschmann includes M. spinalis cervicis in the triangle formed by the rear of the rear of the cervical spine, the withers, and the shoulder blades, “… an extensive connection between the head-neck axis and the truck… it explains how the position and length of the horse’s neck directly affects the biomechanics of the back.” (added 31 Dec 2016)

 

 

How The Anatomy Books (Unintentionally) Fail Us Over The Nuchal Ligament

nuchal-ligament-header-1

The nuchal ligament is a soft tissue structure that is widely discussed in dressage circles. Unsurprisingly, given its deep location, relatively few of us get to cast eyes on it or feel it directly under our hands.

It’s equally unsurprising, then, that most of us don’t realize that the image we hold in our heads is somewhat different to the reality of the ligament inside our horse.

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

I have recently been fortunate enough to attend another dissection with renowned Australian gross anatomist (and she will point out repeatedly that despite this title, she is not gross – or, at least, not that often), Sharon May-Davis.

In this dissection workshop, Sharon had yet another opportunity to show us that an aspect of textbook anatomy is incorrect.

Yes, apparently there are many points where this is the case.

 

Where the nuchal ligament is and what it connects

The structure in question is the nuchal ligament, or the nuchal ligament lamellae to be exact.

George Stubbs illustration

George Stubbs, 1777, showed the NLL attaching from C2 to C7.

To quickly explain, the funicular part of the nuchal ligament is the cord-like part that runs from the withers to the occiput (back of skull). The lamellae is the fibrous sheet-like part that extends from the funicular part to the cervical (neck) vertebrae.

According to the majority of anatomy diagrams and textbooks, it extends down to attach to the cervical vertebrae, from C2 to C7.

According to Sharon, it doesn’t. And here’s why.

 

Findings on the nuchal ligament’s true location

In this study of 35 horses on the dissection table, Sharon found:

  • No cases where the attachments were from C2 to C7.
  • No horses where the attachments were from C2 to C6.
  • In all 35 horses, the attachments were from C2 to C5.
  • And in 9 of the 35, the attachments to C5 consisted of thin and feeble fibers.
  • The horses were of a mixture of identifiable breeds, aged 2 to 28 years old.

So, why do the majority of anatomical drawings of the deeper structures of the horse show something different?

When received knowledge can be a problem

Nuchal ligament, 5yo TB [click to enlarge]

Nuchal ligament, 5yo TB [click to enlarge]

Many of today’s illustrators are referring to illustrations that have themselves been amended from earlier illustrations.

(The header image for this site’s most viewed post, The Disturbing Truth About  Neck Threadworms and Your Itchy Horse, shows an inaccurate rendering of this ligament, as do most of the other illustrations I used. Dang!)

Inaccuracy is a recognized problem when it comes to received knowledge – was this anomaly due to an earlier artist’s error, or was it a characteristic of some 17th century horses that has been progressively bred out over subsequent centuries?

  • And this raises the question of which structure, exactly, is supporting the base of the neck of the horse in motion? Read more about m. Spinalis cervicis in this post, Meet Spinalis, the Forgotten Muscle in Saddle Fitting.
  • And how does this awareness inform current training approaches that require horses to raise themselves into self-carriage?

The findings from this study are in a peer-reviewed paper by Sharon May-Davis and Janeen Kleine currently in press with the Journal of Equine Veterinary Science. The paper includes a detailed review of illustrations in equine anatomy literature, an explanation of the study, and a thought-provoking discussion on the implications for our understanding of equine biomechanics.

Variations and implications of the gross anatomy in the equine nuchal ligament lamellae, Sharon May-Davis, Janeen Kleine, Journal of Equine Veterinary Science 30 June 2014 (Article in Press DOI: 10.1016/j.jevs.2014.06.018)

Have you read about Sharon’s findings on arthritis of the humeroradial (elbow) joint in all ridden or driven horses?

 


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Equine Lyme Disease Doesn’t (Officially) Exist In Australia – Here’s How it Affected One NSW Horse

Lyme-headerAccording to various authorities, Australia has no Lyme disease, human or equine. Despite this, many Australians are testing positive – and that’s happening with horses, as well.

 

The following guest post by Cherry Kawamoto charts a journey about the difficulties of identifying and testing for Lyme disease. It relates to her 3yo mare, an unstarted performance horse that I have worked with several times. It first appeared as an article in Equine News, an equine magazine published in Northern New South Wales.

Lyme disease is tick-borne, and a bite from an infected tick transfers the bacteria to humans and animals, including horses. For horses, the varied signs may include stiffness, swollen joints, shifting lameness, muscle tenderness, behavioral changes and certain neurological effects. The sheer range makes it hard to diagnose, yet if caught early, the prognosis for full recovery is good, following administration of antibiotics.

That uneasy feeling that something wasn’t quite right

A single horse in a herd can suffer Lyme disease

A single horse in a herd can suffer Lyme disease

My mare was always the odd one out in a small herd of youngsters. Dull coat, an incidence of unexplained hind leg tremor, uveitis-like syndrome blamed at the time on an old corneal scar, general gait stiffness and on and off right hind lameness accompanied by swelling of the hock joint and below.

Then there were the little things, such as positions that would worry her when being trimmed, and unexplained twitchiness about some joints when being body worked. But she showed no aggression, choosing instead to walk away or use her weight to make her point. We shrugged this off as something that she would overcome, given time and training.

At first, I insisted on vet visits for each significant incident. Each visit ended with practical recommendations to treat the symptoms and monitor. With most cases, she improved and seemingly recovered. There was no need to dig deeper.

But as the number of such incidences – both recurring and new – grew, I knew that it was well beyond the law of probability: how could one horse be singled out for so many issues? Something was definitely wrong.

In the meantime, this normally laid back and gentle mare was becoming irritable and a little intimidating. She bit an unsuspecting bystander on the chin (my unlucky husband) and even launched an attack on the household dog.

She became increasingly sensitive to being groomed on her near side and she twitched when she felt our hand touch the sides of her face. The rugs started to consistently slip to the left as she shaped her body to attain a position of comfort under their weight.

But there were days or weeks at a time when she seemed better. On those days, I gently worked her from the ground, mostly at a walk. Even then, I found her somewhat reluctant, and the performance variable. On some days, her hind end engaged effortlessly, and on others, she just resisted all efforts towards a square halt. So after a while, I took the hint and left her in the paddock to take an indefinite holiday.

What next? A worsening of the signs, that’s what

The following Spring, the fresh winds brought her to new heights of sensitivity. She remained on high alert and shied at seemingly nothing. Even the dangling belly straps on her rug became threatening enough for her to consider bolting off.

Then suddenly, she had another inflammatory attack, this time on her left hind. It was a significant departure from the usual pattern: for the past 2 years, the problem had always been her right hind, fueling suspicions that it was some sort of a paddock trauma with periodic setbacks.

But this time it was her left hind. I analyzed the situation. She was not in work, so it could not be work-induced. She was not nursing any stiffness, so it could not be a compensatory problem.

I looked to the paddock for clues. Although generally the type that likes to remain ‘parked’, she hypes herself up during herd gallops and launches her massive frame into the air like a 747 – a reminder of her lineage of Grand Prix showjumpers. But the ground itself gave no indication of any such activity. I wondered if it might even be an unfortunate kick from a paddock mate.

My fears disappeared in a few days, when the inflammation subsided.

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A growing suspicion: could it be Equine Lyme disease?

The black-legged tick carries Lyme in the US, but isn't found in Australia

The black-legged tick carries Lyme in the US, but isn’t found in Australia

Then one morning, as on so many mornings before, I found myself scrutinizing the mare from a distance and contemplating the situation. As I stood there, the drifting information in my mind seemed to crystallize and I suddenly knew what to do. I found myself calling our horse vet to ask whether we can conduct a blood test – one that would specifically include Lyme Disease.

In all honesty, I wasn’t sure if my request would go down well. Has there ever been a documented case of equine Lyme in Australia? I was well aware of its controversial nature for human cases.

On the other hand, I was quite comfortable that the clinical symptoms of equine Lyme could explain all of my mare’s unfathomable health history.

My vet patiently heard me out, and agreed to test for Lyme. He also suggested a general blood test, as well as tests to cover other viral and bacterial diseases that might cause one or more of the mare’s symptoms. I thought it was an excellent suggestion.

The test results offer hope – of a kind

Several weeks later, we had the full results. Blood biochemistry and hematology was normal. She was negative for leptospirosis, which might have otherwise explained her uveitis. There were many other viruses she tested negative for.

Equine Lyme mare

All looks normal, but the test for Equine Lyme is positive

But, she came back positive for earlier exposure to Ross River Virus (not currently active) and Lyme. It’s quite common for horses in endemic regions to have full immunity and therefore test positively for Ross River Virus (RRV), without it ever having been detected in the past.

Yet for those horses that succumb to significant clinical symptoms upon infection, it may take many months, even years, for them to build up full immunity. Until such time, symptoms associated with RRV may recur, especially in times of stress.

It was difficult to think about the implications of a RRV diagnosis in my mare’s case: it could explain some of the symptoms, such as recurring stiffness and swollen joints. On the other hand, she may already have attained full immunity. Yet as there’s no medication to eradicate the virus, there wasn’t much we could do in any case.

Lyme, however, is treatable. This gave us the possibility of confirming or disproving the diagnosis by observing my mare’s response to treatment.

 

Ticks usually carry Equine Lyme

Australia has no shortage of tick species – here are just three

But what about the Equine Lyme disease test?

The Lyme blood tests are notoriously unreliable indicators, producing false positives and – more often – false negatives. The fact that the bacteria can remain undetected by the horse’s immune system means there are fewer antibodies and therefore a greater chance of a false negative result.

There’s also an issue in that there’s no central body controlling the standard of the tests. This means that the ‘gold standard’ approach is to undertake at least 2 blood tests based on different methodologies.

We sent off a request to the US for more testing, with a 6-week wait for results.

There are now suggestions from reputable sources (ie, producing peer-reviewed published research) that different strains of bacterium may be present in Australia, and that these may be vectored by the biting March fly rather than ticks. Here is a starting point for more reading.)

 

Could the March fly carry Lyme disease?

Could the March fly carry Lyme disease?

To act or not with a partial Lyme Disease diagnosis

With a second test underway, my vet and I decided to place faith in the results so far, and started my mare on an initial 6-week treatment for Lyme. This consisted of a course of three different antibiotics.

The early signs were encouraging. For each new course of antibiotics, she presented with inflammation in different parts of her legs, and patchy sweating on different parts of her body. This is consistent with the Jarisch-Herxheimer reaction, which is well-documented in human Lyme cases. It’s the body’s response to endotoxins released by a mass of dying bacteria.

We continue to monitor her closely. She is becoming more social and less flighty under windy conditions. She is no longer so sensitive around her head.

Is it Lyme? Possibly. Will she be cured? I hope so.

Our journey continues.

 

The intention of this article is not to pinpoint Lyme as the culprit of all vague and unexplained ‘unwellness’ and ‘misbehavior’ in horses. It is written in the hope that the information will provide horse owners with other avenues for investigation where the more familiar possibilities have been exhausted. Most importantly, it will hopefully encourage all horse owners to diligently keep a record of their horse’s health and psychological well being, as it was just such an approach that has helped us.

 © All text copyright of the author, at www.thehorsesback.com. No reproduction of partial or entire text without permission. Sharing the link back to this page is fine. Please contact jane@thehorsesback.com for more information. Thank you!

About the author: Cherry Kawamoto (BSc) recently moved back to Australia from Singapore to set up MF Equestrian, a boutique training facility in Nana Glen, NSW. This caters for young horses and riders. For more information, please contact Cherry on mfequestrian88@gmail.com

Buying an Ex-Racehorse: Can You Spot the Major Physical Issues?

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The ex-racehorse: a huge heart, a strong work ethic, great athleticism, wonderful sensitivity… and, potentially, a host of physical issues. Are you able to identify the problems so often present in these superb equine athletes?

A sports career can be tough on the body, as any committed athlete will admit. No matter how successful the athlete, the wear and tear and dings and dents will just keep on coming. It’s an inevitable consequence of making the body work at its outer limits of strength, speed and endurance: there are going to be times when the body just can’t make it or just can’t take the pressure. And that doesn’t count the spills and collisions that happen along the way. The same is as true for any top athlete as for any trainee who doesn’t make it past the foothills of success. And the same is definitely as true for racehorses as for any human Olympiad.

© All text copyright of the author, Jane Clothier, www.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!

** Questions, thoughts or comments? Join us at The Horse’s Back Facebook Group


The damage carried by ex-racehorses

racehorseJust how much damage an ex-racehorse displays in its physique depends on several things:

  1. the methods of training used,
  2. the speed with which the training was introduced and stepped up,
  3. the athletic qualities of that horse’s body – conformation, maturity and sheer unquantifiable athleticism,
  4. the treatment given and recovery time allowed for injuries at the time they occurred – assuming all were recognized (not all are visible or obvious),
  5. the demands placed on the horse in terms of number of races and recovery time between races,
  6. the length of time spent in racing, enabling the above to occur,
  7. the horse’s mental and emotional ability to cope with physical problems (it varies enormously).

exracer1As in any sport, there are things that are done well, and things that are not done so well. Informed training and misinformed. Well judged and misjudged. Just as in the rest of the equine world.

Some thoroughbreds come out of the racing industry in fine fettle and have splendid second athletic careers in high end competition. Many have lower level issues that come right with some rehabilitation, leaving them suited to successful but less demanding careers. Others may be more suited to recreational homes, where life is one long pleasurable trail ride.

Unfortunately, many thoroughbreds with moderate problems land up in homes with people who are quite unaware of their horses’ issues.

 

What would you look for when buying an ex-racehorse?

pleasurehorseWhen working with clients, I see a range of issues that come up again and again in ex-racehorses. I also see plenty of unsuspecting owners who didn’t know what they were buying at the time.

There’s a huge amount of love around, but the horse is often showing discomfort or pain, and the owner is only just realizing that (a) their horse may not be able to participate in the activities they’d hoped to experience together, and (b) getting the horse to a point when they can deal with these issues may cost considerably more than the horse did upon purchase.

It’s a sad situation. I believe that when looking at ex-racehorses, even those that have already had a couple of non-racing owners, you could do a lot worse than check for the physical issues listed here. Even better, get a vet to check the horse… but even then, you could run through this checklist before getting the vet in.

Don’t forget to read this guest post: 8 Golden Rules for Helping Your Thoroughbred Get Right Off The Track

There’s functional and not-so-functional when it comes to ex-racehorses

Not all the physical issues are deal-breakers, of course. A horse can have one or two and still be able to function perfectly well (although if it’s straight out of racing, some rehabilitative work is going to be necessary). A big part of your buying decision will come down to:

  • the number of issues you can identify,
  • the severity of those issues,
  • what has already been done to assist the horse with those issues,
  • how much they will affect the kind of riding you wish to do, and
  • whether YOU are capable of providing the rehabilitation and retraining needed to support the horse through those problems – or if not, whether you can afford to pay somebody else who can.

The list that follows is by no means exhaustive – there are always more problems, especially as a combination of different problems can throw up further secondary issues. And I don’t go into hoofcare, which is worthy of another introductory article in its own right. However, it’s a major issue, so I’d recommend learning more about that too.

What I’ve decided to focus on here are problems that you can identify quickly and relatively easily. Most are visually identifiable. You can then get a more knowledgeable person to help you assess the horse or get a vetting completed before making a decision. Better still, do both.

 


Don’t forget to read about the congenital skeletal anomaly that’s affecting TBs and TB-derived breed horses the world over: All You  Need to Know Abut the Hidden C6-C7 Malformation That’s Bringing Horses Down.



1. Sacroiliac Damage – Not Whether it’s There, but is it Sl
ight, Bad or Appalling?

This problem really is the number one, as every ex-racehorse has damage to the ligaments in this area. Depending on severity, there can be lesions that have healed, or lesions that have resulted in lasting weakness.

Frequently, when damage to the ligaments is  severe, there’ll be further changes to the pelvis that are also visible. These may may or may not have the same root cause (see 2, below). One general rule, though, is that the horse won’t be symmetrical.

SAMSUNGMajor damage can rule out a future athletic career, while moderate damage may require rehabilitative work to strengthen the back and prepare the horse for future work. Minor damage isn’t necessarily an issue once the ligaments have healed.

Check for: asymmetry of the tuber sacrales (the two bony ‘pins’ of the croup), with one side being more than 5mm higher than the other. The horse may walk with one side of the pelvis lifting higher than the other – a hip ‘hike’. The muscle development over the glutes on top of the hindquarters may be uneven. These horse are nearly always cagey about picking up a back foot – they’ll swiftly lift it really high and then lower it into position. The horse can also find it hard to stand square, instead standing with hind feet close together – one toe may be angled outwards. Always look for problems with the lumbar spine as well (see 3, below).

Click to Tweet this important point: “The Ex-Racehorse and Sacroiliac Damage – Not whether it’s there, but is it slight, bad or appalling?” www.thehorsesback.com/ex-racehorse-problems

 

Sacroiliac dysfunction2. The Pelvis Can Be Equine Ground Zero

As well as sacroiliac problems, ex-racehorses can have other structural damage to the pelvis. Some of it you can see, some of it you can’t. The most important thing to do is check the pelvis for overall symmetry. What you’re checking for isn’t just pelvic rotation, ie. one side being higher or further forward than the other, but also distortion.

Distorted PelvisIn horses that have had heavy accidents at a young age, the pubic symphysis (the lower cartilaginous join between the pelvic halves, directly between the legs) hasn’t formed properly. The pelvis may be forced wider due to impact or stress, and this part never joins.

What problems does this cause? With a severely distorted pelvis, a horse can’t work equally well on both reins and may not be able to canter at all on one rein. These horses also have a higher risk of having hidden stress fractures – hairline fractures that can worsen after a further fall or trauma later in life.

Indeed, make sure that all the pelvic ‘bony landmarks’ – the point of hip, point of buttock, croup – are actually present. Sometimes fractures lead to ‘knocked down hips’ or one tuber sacral may have dropped due to a fracture of the pelvic wing.

Check for: Pelvic symmetry, by checking the positions of the bony landmarks. If you know the horse and it’s safe, stand on a box a few feet behind to take a look down the back of the squared up horse (if it can square up, that is). Otherwise, hold a mobile phone directly overhead to get a straight-down-the-back photo, ensuring it’s dead center. ALWAYS STAY IN A SAFE POSITION – CLIMB ON A FENCE TO LOOK, WHATEVER. JUST STAY SAFE.

 

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



3. Heading North, South, East or West… the Lumbar Spine

If you’ve found any sacroiliac or pelvic issues, you’ll probably find problems in the lumbar spine too. Lateral imbalance in the pelvis will, more often than not, rotate the lumbar spine to one side or the other. Lumbar issues can also be found all on their own.

Lumbar 1A long-term rotated lumbar spine will usually have some fusion between the vertebrae, and/or overriding dorsal processes (the part of the vertebrae you can feel). Fused areas are painful for the horse while they’re happening, and OK once the fusion is complete. But if fusion cracks, it can once more be extremely painful. Many horses compete just fine with some fusion, but if it’s severe, there’ll be problems with flexion, both vertical and lateral.

Check for: Use your hand to check the lumbar spine for the ‘lumps and bumps’ that can indicate overriding processes. Looking from the side, is the lumbar spine raised – ie, a roached back? This will usually tilt the pelvis back if it’s a longer term problem. If the pelvis is tilted forward, you’ll find there’s often a longer dip in front of the croup – the sacrolumbar gap is larger than normal.

 

knees4. Knee Bones: Take a Bag of Chicklets and Shake Them Up

Or so said Tom Ivers, one of the original equine sports therapy experts and a racing trainer to boot. Equine knees are delicate and complex, with many small bones (carpals), and undergo a lot of stress in a racing career.

Problems such as slab fractures and bone chips in the carpal bones happen due to over-extension (when the joint is bent back slightly) at high speed, or from constant loading on the same bend. Then there are more complex fractures, when the carpal bones break into more than two segments.

Check for: Puffiness around the joint, especially in front, due to previous swelling in the joint capsule. Old bone chips and slab fractures may have been dealt with at the time, but there can be lasting damage within the joint that leads to osteoarthritis (carpitis) later on.

 

buckedshins-15. The Stresses Left by Sore Shins

An ex-racehorse may have had an episode of sore shins in its early career. This is stress to the periosteum (the soft surface layer over the bone) caused by concussion – the body’s response is to lay down extra calcium to strengthen the bone. The bone recovers, but anywhere there’s been remodeling, there’s weakness in the bone.

If it’s severe, there may be an undiagnosed stress fracture that can go catastrophic under high pressure at a future date.

Check for: a curvature on the front of the cannon, which indicates that the problem was bad for heavy remodeling to occur.

 

bowed tendon6. Tendons, Tendons and More Damaged Tendons

Injuries to flexor tendons are extremely common amongst racehorses, with the deep digital flexor tendon and superficial digital flexor tendon being the most affected. These can be relatively minor lesions, which heal up quite nicely, to more serious ruptures that end a racing career.

There is always a risk of re-injury due to the weakness, and in serious cases, a second rupture could be catastrophic. It often depends on the quality of treatment and length of rest given at the time, as well as re-conditioning before returning to work.

Check for: a thicker area of the tendons indicates an old injury that has healed, while a curvature along the length of the tendon is a classic ‘bowed tendon’, sign of a far more serious injury.

 

S/W Ver: 96.66.76R7. Small but Vital: Fractures in the Fetlocks

Fetlocks are vulnerable due to hyper-extension, when the back of the fetlock comes too close to the ground when all the weight is borne on one foreleg at high speeds. Extremely high forces occur at the back of the fetlock and pastern as the horse lands the forefoot. Poor hoofcare, in the form of ‘low heel, long toe’ imbalance, also plays a significant part in this.

With fractures, the big, big issue is the type and location. A damaged sesamoid (the two small bones at the back of the fetlocks are the sesamoids)can play havoc with the vital suspensory ligament. So if you see signs of a problem, you’ll always need to know more, and that will usually mean involving a vet.

Check for: Sesamoid fractures will show up as ‘over-rounded’ or ‘apple shaped’ fetlocks, where swelling from an old injury has disrupted the joint capsule and/or extra calcium has formed around a restricted joint. Are the fetlocks of the forelegs the same size and shape? If one joint is larger and rounder, or if the ligament at the back of the foot feels thicker, with puffiness above the back of the fetlock, be suspicious.

Original article by Jane Clothier, www.thehorsesback.com posted 9 Feb 2014. All text and photographs (c) Jane Clothier. No reproduction without permission, sorry.

 

S/W Ver: 96.66.76R8. The Stifles Cop It, Nearly Every Time

There are numerous causes for stifle issues in ex-racehorses, but you can take the view that if there’s a problem anywhere in the hindquarters, the stifle usually suffers. This includes any pelvic imbalance that leads to unequal loading of the hind limbs, never mind the forces of running on a unilateral bend…

Then there are the rotational twists that can happen in collisions and on bad ground. There are so many ligaments around this complex double joint that it really isn’t hard for it to get compromised.

Check for: A regular click as a hind leg starts to swing forward. This is the patellar momentarily catching, which can happens due to the lateral imbalance (causing misalignment in the femeropatellar joint). Other signs are visual: distension (swelling) of the joint may be visible from the side-on view, or from the front looking back towards the tail, depending on which part of the joint has been affected (femeropatellar or femerotibial).

 

Hocks9. Bringing up the Rear: Hocks Are Vulnerable Too

The hock comes under major stress due to being so involved in providing propulsive power in the gallop. As a major hinge joint, it is central to jumping out of starting gates/barriers, when it’s subject to the load of almost the entire horse. In the gallop, it must alternate between being compressed to absorb concussion, being rigid to build energy, and then extending fully to dispel energy and move the horse forwards.

Frequently, it’s doing this while subject to uneven loading on a bend. Then there are the unplanned twists and traumas. Well-conformed hocks may deal with this pretty well, but over-straight hocks and ‘cow hocks’ mean that the joint is less able to withstand high levels of work. It’s common for DJD to develop in the lower bones of the joint, especially on the side that’s on the inside of the bend the horse raced in.

Check for: look for puffiness on the face of the joint. Also look for bog spavins – these are specific fluid bumps on the front of the joint, which indicate underlying issues. Bone spavins are their bony equivalents, being hard bumps lower on the face of the joint, which indicate the presence of established DJD (arthritis). Also, listen for a crunching noise or a crack when the hind foot is lifted.

 

S/W Ver: 96.66.76R10. A Crash and Bang on the Shoulder

Racehorses can experience awkward impacts at the base of the neck, above the point of the  shoulder. It can happen when bunched-up horses collide or run against railings, during a fall, or through everyday routine, such as a severe knock against a stable door. One outcome can be damage to the supraspinous nerve, which runs over the face of the shoulder blade (scapula).

When damaged, this can lead to wasting or even paralysis of the muscles over the shoulder blade itself, which is a problem, because these muscles stabilise the shoulder joint. This condition is known as ‘sweeney’. Mild cases usually recover, but more severe cases can be left with permanently wasted muscles. With reduced function in one shoulder and a shortened stride, the horse won’t be suited to demanding sports.

Check for: a lack of muscle over the shoulder blade itself. This is more than just tight muscles – the spine of the shoulder blade will be visually obvious and easy to identify through touch.

 

And There’s More… There’s Always More

S/W Ver: 96.66.76RIt’s hard to know where to stop with an article like this, but I hope this is a good start when it comes to assessing a horse. You may be thinking that many of the problems are those you should check for in any new horse purchase – and you’d be right. However, anyone who works regularly with ex-racehorses will recognize that there are certain sets of issues that come with these former athletes.

What I haven’t covered: neck issues are common (calcification at the top of the nuchal ligament, misshapen atlas and atlanto-occiptal junction, etc), hidden stress fractures (radius and tibia are most common, but also the scapula… and others), the fractured ribs that come with sideways impacts in a race, misalignment through C6-T4, and quite a few more… but all are harder for the non-professional to assess.

Other information is more of interest to people working in the field. For this reason, I’m adding some links below. Please feel free to mention your own in the Comments…

To finish off, here are two horses that raced in Australia, where it’s common to train horses at the very racetrack where they run most of their races. In the state of NSW, the horses run clockwise (the bay), while in the state of Victoria, they run anti-clockwise (the chestnut). A view straight down the ‘unstraight’ spine can tell you so much!

 

spines

 

 


Now check out this article OTTB rehabilitation: 8 Golden Rules For Helping Your Thoroughbred Get Right Off The Track


Questions, thoughts or comments? Join us at The Horse’s Back Facebook Group


 

 

Revealed: the Common Equine Arthritis You Won’t Read About in Textbooks

elbow-header2

Sometimes, a person from outside a profession successfully identifies something that has been unnoticed, overlooked or wrongly assessed for a long, long time. Coming from another direction, they see something that has been hidden in plain sight, simply because nobody looked there before.

Take amateur astronomers. They’re particularly well known for rocking the scientific community. In 2009, Australian Anthony Wesley discovered a visible scar left by a comet or meteoroid that had slammed into Jupiter, and we’ve all heard about Mr and Mrs Shoemaker and their neighbor Mr Levy and the comet they discovered in 1993.

Unusually, the astronomy community is able to recognize that while professionals have more technical background to analyze data, amateurs still play an important role in collecting it.

You might think that there’s no new data to be collected about equine pathologies, because every condition that can affect a horse, certainly above the level of microbiology, must already have been charted, mapped, researched and thoroughly understood. But, in the words of the song, it ain’t necessarily so.

Sometimes, all it needs is for someone else to be looking. And if that someone is looking with a rather different set of eyes or from a slightly different direction to the conventional scientific community, some rather remarkable results can come about.

 © All text copyright of the author, Jane Clothier, www.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!

One lady who’s working in the field

If you’re looking for a different set of eyes for equine musculoskeletal pathologies, they don’t come much sharper than those of Sharon May-Davis. Few people have the razor sharp eye she has for a hidden pathology or condition in the horse.

She’s held in high esteem by riders in the sporting fields, because as an equine therapist, she has managed elite equine athletes at State, National and Olympic levels in 7 different disciplines including the recognized FEI ones such as eventing, dressage, showjumping and endurance. This has been accompanied by her extensive experience in the Australian and Japanese racing industries.

Teaching biomechanics, Sept 2013

Sharon, seated, teaching biomechanics, Sept 2013

Sharon is also a biomechanics expert, a university lecturer in equine therapies and anatomy, and – significantly – a practical anatomist.

She has been conducting private equine autopsies for many years – it’s not for nothing that she’s been labeled The Bone Lady and Equine CSI. She also uses these 2-3 day dissection workshops to teach equine professionals and horse owners more about how their horses move and the damage their bodies can incur as a result of breeding, illness, injury or work.

She has been dissecting for personal research for over 20 years and professionally for 14 years. In fact, she now conducts up to 15 professional dissections per year – that’s a total of around 300 dissections so far.

Sharon is the first to state that she isn’t a vet and doesn’t hold a doctorate, but as a practicing equine scientist, researcher and practitioner, she is uniquely placed to provide a source of raw data that is all but unparalleled.

Evidence from the dissection table

Some years ago, Sharon noticed an unusual action in the elbow of horses. She mentioned this to qualified practitioners and was informed that this action was quite normal. Not convinced, she began videoing horses prior to dissection and, within a short period of time, was able to match this action to a change in the elbow.

Humerus, radius and ulna, showing damage to cartilage

Humerus, radius and ulna, showing damage to cartilage

Not to beat around the bush, it’s an unusual form of degeneration in the horse’s elbow joint that involves all three bones. It’s a form of osteoarthritis that strikes the humeroradial joint and the ulna, causing deep and dramatic gouges into the cartilage, and eventually eroding bone.

When the joint is opened up, blood is frequently found in the synovial fluid (haemarthrosis). The fluid also displays decreased viscosity.

This is more than a little bit odd, as arthritis of the elbow is supposed to be rare in the horse.

Yet Sharon has found it to be present in numerous horses that have been euthanized under veterinary supervision for completely unrelated reasons.

Note: that’s not just some horses, but many.

Do you know where the nuchal ligament attaches on the cervical vertebrae? You think so? Evidence from the dissection table might prove you wrong – read more about Sharon’s findings on the nuchal ligament’s lamellar attachments…

This equine arthritis is visible in the living horse

The vital connection from video to dissection has enabled Sharon to indicate the presence of the elbow osteoarthritis in the horses she had been treating as an equine therapist.

It’s easy to spot, being a noticeable jarring in the elbow as the horse moves downhill – a kind of double action – you can see it here. Significantly, it’s what can be termed a gait anomaly, rather than lameness.

(If you can’t see the above video, you can view it here.)

Does it look familiar? It’s very likely that you’ve seen it in horses before and wondered what it was. The fact is that it’s so common, many people think it’s a normal action. It’s not. It’s a form of equine arthritis.

Sharon tells us she has seen the elbow problem in all types, breeds, sizes and ages of horses. Some affected horses have been elite dressage and eventing competitors. Interestingly, the problem is only presenting in ridden and driven horses.

If never worked, horses appear to remain forever free of this particular joint change.

Why the fuss – isn’t this just regular arthritis?

No. Arthritis of the horse’s elbow is considered to be rare in equine veterinary medicine.

How it should look: healthy radius and ulna (unridden horse)

How it should look: healthy radius and ulna (unridden horse)

The key to why it doesn’t often get diagnosed and is considered rare could be the absence of visible lameness. The arthritis identified by Sharon does not cause a distinctive lameness in the horse, although it does bring on a notable gait change, with the double step in the joint’s motion on the downhill.

Riders of such horses often just feel that their horse is a bit ‘off’, feeling a hesitation in the movement, but without being able to define the point of origin.

There are a couple more reasons why it’s not very visible: first, the action of the elbow is highly integrated with the overall shoulder action, and second, the massive triceps muscle has a further stabilizing effect on the joint.

Radius and ulna of ridden horse, showing cartilage wear and blood in joint

Radius and ulna of ridden horse, showing cartilage wear and blood in joint

And even if the elbow is explored, the relatively tight joint space means that degenerative problems are rarely seen in diagnostic imaging, although inflammation can show up in thermographic images.

When, unusually, a problem has been recognized and vets have attempted a corticosteroid injection of the joint (which happens to be the most difficult joint to access), blood has been found to be present.

A closer look at Sharon’s findings

Sharon May-Davis first presented some of her findings into elbow arthritis at a conference in Australia in February 2013: the Bowker Lectures at the Australian College of Equine Podiatherapy. Presenting alongside Prof Robert Bowker and Dr Bruce Nock amongst others, she discussed the club foot in the horse, and noted how the elbow degeneration she observes on the dissection table is always worse in the forelimb with the more upright hoof.

 

If the condition is bilaterally present, it unfortunately appears worse on the side with the slightly upright or higher hoof. What’s more, and according to Sharon, this also applies to the limb where an inferior check ligament desmotomy (surgery undertaken with the aim of correcting an upright hoof) has taken place and the ligament has later reconnected.

She has, as already mentioned, since established that it can occur in any ridden or driven horse. Here, she describes the problem in her own words.

“The action looks like a slip and or clunk into the shoulder or a shudder or a sliding / slipping action. It depends upon your perspective. The actual change in the action begins when the foreleg is in the ‘Stance Phase’ during the stride as the limb goes into the posterior phase of the stride. It is more obvious going down a hill.

“So far, 100% of ridden horses exhibit this condition to a varying degree (under dissection). Horses not ridden and with no abnormalities do not exhibit this condition (under dissection). Horses in harness also exhibit this condition.

“What does the joint look like? There appears under dissection to be substantial degradation in the cartilage of the humerus, radius and ulna.

“Most horses appear to handle this condition and continue with a normal life if not pushed to extremes. Although this sounds career-ending, in fact it is not. Once the horse gets through the worst of the wear pattern they re-settle in the joint and continue on with work.

“High level competitors require joint support to help sustain the elbow and other joints that may compensate for the change in action.

“Horses that jump are more inclined to land with straighter forelimbs. Be mindful that jumping and downhill work could possibly make the condition worse.

“Riders often feel instability in the horse’s forelimbs when traveling downhill and some even question the horse’s proprioception.

“Bodyworkers massaging the triceps (particularly the lateral triceps) actually exacerbate the condition as the massage releases the cast-like formation that this muscle provides.”

 

More research is needed, but so is support

Humerus and radial bones of ex-racehorse, showing arthritic wear

Humerus and radial bones showing arthritic wear

Despite finding and documenting a huge number of dissection cases involving this particular issue, all unaided and unfunded by outside bodies, Sharon has consistently met with brick walls and skeptical responses when she has put the information forward to relevant authorities.

Why? It’s not as if she’s new to this. She has previously identified congenital malformations in the caudal cervical vertebrae of thoroughbreds, and in the atlas of Spanish Mustangs, as well as asymmetries in the femur structures of racehorses due to racing (published in the Australian Veterinary Journal).

She isn’t looking for funding (although she obviously wouldn’t say no), but would like to have this research taken up for the benefit of all ridden and driven horses. The sooner the problem is recognized and investigated, the sooner that episodic pain in the horse can be recognized, with appropriate joint support or rest given where appropriate.

And the sooner we can all learn more in our great drive towards improved equine health, the better. As Sharon says,

“In truth, we are still in the dark. Seeing it is one thing, analyzing it and providing a preventative program is something totally different.”

 


Questions, thoughts or comments? Join us at The Horse’s Back Facebook group. 


 

Two more cases (added January 2014)

Case 1: Thoroughbred gelding

Raced, then showjumped to ‘B’ grade, before being ridden as a trail horse. Euthanized at 14 years due to ongoing colic issues. Here is a video of this TB, filmed in 2011:

 

Here are images from the dissection table:

TB gelding radius and ulna, showing wear and blood spot.

TB gelding radius and ulna, showing wear and blood spot.

 

TB distal humerus, showing significant wear to cartilage.

TB distal humerus, showing significant wear to cartilage.

 

Read more about ex-racehorses and their prevailing physical problems here.

 

Case 2: Warmblood gelding

Showjumped up to 10 years. Competed in dressage from 11 years. Retired from riding at around 20 years due to unresolved lameness.

Here is a video of this horse, showing severe elbow degeneration (as well as other pathologies):

 

 

And here are images from the dissection table. Note the bruised and bloody cartilage of the radius, ulna and humerus. Also, the droplets of synovial fluid are discolored, being a very unhealthy reddish brown.

 

WB: cartilage wear evident in the radius and ulna.

WB: cartilage wear evident in the radius and ulna.

 

WB humerus showing significant wear.

WB humerus showing significant wear.

 

WB humerus showing wear - note spots of synovial fluid showing brown discoloration.

WB humerus showing wear – note spots of synovial fluid showing brown discoloration.

More Information

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Sharon May-Davis, B. App. Sc. (Equine), M. App. Sc. (Ag and Rural), ACHM, EBW, EMR was the Equine Therapist for the Modern Pentathlon Horses and the Australian Reining Team at the Sydney 2000 Olympics. She has worked with the Australian Champion from seven differing disciplines and has a particular interest in researching the musculoskeletal system. She also conducts clinics and seminars in relation to her work and regularly presents in the Northern and Southern hemisphere.

You can learn about Sharon’s work and approach in this interview: Skeletons from the Bone Lady’s Closet.

Meanwhile, Sharon is answering questions in the comments section, below. Discussion is positively welcomed, so please feel free to ask questions or share experiences. Sharon will drop in to answer them if you do.

 

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

 

 

After the Storms: 6 Ways to Help Your Horse’s Skin Recover

It’s not much fun being hit by 3 days of an ex-Cyclone’s wrath, as dwellers on Australia’s east coast have just learned. In the aftermath of the storms, an unusually high number of owners are reporting a problem common to horses caught in the big summer deluges of the tropics and sub-tropics.

A huge number of horses are experiencing swollen lower legs courtesy of ex-cyclone Oswald. Many may be due to lack of movement and build-up of lymphatic fluid due to reduced circulation, but many are getting sore with signs of scabbing too.

Let’s take a look at the problems where the skin around the lower leg, and pastern in particular, remains swollen, reddened in the case of white feet, or starts to get crusty skin or scabbing.

The Cause: Mud Fever, aka Greasy Heel

Greasy heel, aka mud fever, aka cracked heels in its earlier stages.There’s no doubt about it, Aussie owners aren’t as familiar with mud fever as owners in countries that are far more – well – muddier. Hailing from England, I know about it only too well. Yet in this wide brown dry land, where it also goes under its local name of greasy heel, it’s far less common.

The cause of the swelling and crusting skin we see with mud fever is a reaction to the early stages of bacterial or fungal infection.

Put simply, during the periods of unrelenting rain, the skin becomes softened and the many microscopic scratches around the pasterns and lower legs are exposed (imagine tiny scabs going soft).

The ‘bugs’, which thrive in damp conditions, enter these tiny scratches and abrasions. As the horse’s body starts to fight the invaders off, the swelling occurs.

Not all horses will develop the problem further, as it depends on how strong their immune systems are. Some will fight it off. But while there’s visible swelling, possibly accompanied by redness on white legs, sometimes with crusting skin and the beginnings of scabs, the horse’s body is in defense mode.

The problem usually affects the hind legs more than the front, but as it progresses, all four legs can be affected.

 

Partner in Crime: Rain Scald

Rainscald (c) horsetalk.co.nz

Rainscald, also known as rain rot, is caused by the same bacterial agents and is also a form of dermatitis. The bacteria cluster in the damp, warm zone at the base of the hair, next to the skin.

You don’t see the signs as quickly as with greasy heel, but you may notice your horse has increased sensitivity along the centre line of the back – especially if they are rather overweight and have a ‘rain channel’ down the middle.

 

Where Does Greasy Heel Come From?

Both rainscald and greasy heel/mud fever are caused by an invading dermatophilus or staphylococcus. Greasy heel may also be caused by fungal infections such as dermatophytes (thanks to the Horses and People fact sheet for the names.)

The microbes that cause rainscald are often already living on the skin of horses, without causing any problems. However, during a period of heavy rainfall, especially in our warm regional climate, they become more active and release ‘zoospores’. They get happy: they breed. The spores infect the skin where it’s weaker, with the discharge then clogging into the familiar paintbrush tufts of hair and scabs after a few days.

It’s entirely possible that some paddocks present horses with the greasy heel and rainscald bugs more than others. I’ve certainly had horses that were fine until they changed properties and then suddenly seemed to ‘pick something up’.

 

Why Is This Such a Problem After Flooding?

Rain rot aka greasy heel (c) horsetalk.co.nz

Good question. It’s not as if we don’t regularly get 2 or 3-day episodes of non-stop rain. The high incidence of swollen legs relating to mud fever may be due to several things. Shall we speculate?

The weather was extremely hot before and after, while still pretty warm during the event. The conditions may have been particularly favorable to the bacterial activity. Also, with such high winds, it’s very likely that horses stopped moving around as much. Lack of movement leads to poor circulation, which leads to fluid build-up anyway, as well as reduced resistance to nasty little invaders.

But in truth, I don’t know for sure. I’d be interested to hear other ideas. (There’s a comments section at the end.)

Whatever the reasons, I still feel it’s best to come down hard on problems like mud fever or rainscald, as they’ll only come back another time, making your horse uncomfortable and setting you to work on it all over again.

 

Are These Problems Serious?

Rainscald    (c) horse-pros.com

These infections can be surprisingly painful for the horse. If your horse has greasy heel and scabs form, and your property is still flooded or at the least muddy, then you need to act quickly if it’s not to become a more serious problem. The horse needs to flex at the fetlocks whenever it moves, so if the scabs remain on the pasterns, they will crack repeatedly and the lesions beneath will grow larger. (This is why the condition is also known as cracked heel.) Your horse may well become lame.

Rainscald is painful for the horse even before the ‘paintbrush tufts’ appear. It will remain so until the scabs have all come away and the skin beneath has healed. Horses severely affected by rainscald may develop a fever, become depressed, lose their appetite and become lethargic. They may also have swollen lymph nodes… these are all signs of a body defending itself against infection.

 

How to Treat the Bacteria

Cleaning and treating legs  (c)Equiderma.com

Once you realize you’re looking at infection, it becomes more apparent that something needs to be done. There are many suggested remedies you can try once the reaction has started – here are a few.

The initial swelling should subside with movement and exercise, as the lymph fluid is shifted away.

If the horse has developed scabs, you can soften and remove these before applying treatments. I’ve previously used aqueous cream for small scabs, which soaks and lubricates them, so that they then slide off gently. I’ve also seen paraffin oil or olive oil suggested. If the scabs are covering much larger lesions, you may need to progress more slowly, over several days, as removal will be painful for the horse.

Here are some treatments you can try, recommended by different people in the equine industry.

  1. A diluted iodine solution can be used on the legs, to zap the bacteria.

  2. For greasy heel and rainscald, an anti-microbial shampoo is another option for scab removal – Maloseb, normally used for cats and dogs, is gentle and contains chlorhexidine gluconate (2% content).

  3. For rainscald, you can ease off the scabbing at an early stage, either with an oil-based product, or even with olive oil, before rinsing the back with iodine. Use it well-diluted or it may sting.

  4. Products used by vets and medical staff containing chlorhexidine gluconate offer a gentle antibacterial action. Microshield is a good product (5% content) that can be diluted and used on horses’ legs and backs. You can buy it online or from Chemists Warehouse in Australia.

  5. A poulticing product such as Tuffrock can be applied to the affected areas. This has some antibacterial properties – if scabbing is present, it’s better to also use an antibacterial agent.

  6. The herbal approach (suggested by Herbal Horse) is to use coconut oil on the lower legs. You could also try using this before the rains come, providing  you have advance warning, so that a protective layer is built up. This can help prevent bacteria from entering the skin.

 

Make Greasy Heel Go for Good

Dealing with rainscald   (c)horsetalk.co.nz

If infection is present, you may need to work on the area for a few days running to ensure that the bacteria are well and truly zapped. You want to reduce the chances of it recurring – ridding your horse’s skin of the bacteria is definitely one way to do that.

That’s not to say it’ll never happen again, but as ever, prevention is better than cure. One of the most helpful things we can do for our horses is to work on their underlying condition, boosting their immunity through use of probiotics to improve gut function, while providing adequate nutrition and mineral supplementation.

And – well, I would say this – bodywork will ensure the upper layers of tissue, including the skin, are nourished and functioning as they should, while circulation is good.

Extreme weather is never easy to deal with, but with a bit of organization, we can ensure our horses come safely through it without experiencing an unnecessary degree of discomfort and even pain.

Two Interesting Cases from the Saddle Mortuary

It’s not often that I get asked to take part in a cull, but that’s exactly what happened last week.

The venue was a riding for the disabled center, where elderly, unused saddles were threatening to take over the tack room, forcing out newer, kinder-on-the-horse saddlery. It was time to free the tack room of this tyranny by an older generation of equipment.

After receiving a tip-off that it could get messy, I dressed in old clothes and headed off to the center, ready to do whatever it would take to get those saddles out.

What I found

It wasn’t pretty. More than 20 old saddles, in varying states of decay, were stacked three deep on the saddle racks. They outnumbered the saddles currently in use by at least 3 to 1.

This is what happens when ancient saddles that are well past their sell-by date (often literally – nobody would buy them, even on ebay) are given to RDA centers. People are donating from the kindness of their hearts, but unfortunately, very old and damaged equipment can’t be used.

Destination: the refuse tip

Back to the cull. What I’d been asked to do was sort out the saddles that were damaged or that weren’t horse-friendly by modern standards. (As you’ve probably noticed, saddle design has moved on a lot in recent years, taking in newer understandings of anatomy and biomechanics.)

I sorted the saddles into two piles: suitable for use by the center and unsuitable.

We ended up with three saddles in the suitable pile – these would be fitted to some of the center’s horses. There were 19 in the unsuitable pile.

The latter group shared a number of now-undesirable features that are common to saddles from over 20 years ago: wither-gripping gullets, spine-pinching channels and cheese-wire width panels. What’s more, they showed some sorry signs of ageing: lumpy panels and, horror of horrors, twisted trees.

The next stop for this lot would be the refuse tip. All would first be slashed with a craft knife first, to ensure that nobody else would pick them up and take them home. (Yes, I know people don’t have a lot of money, but most ponies don’t have a lot of backs either. These saddles would damage horses’ backs if used. They had definitely had their day.)

Despite this, the pile was interesting in its varied peculiarities. So, before the haul was shipped out the gate, I took a closer look at two of the saddles.

Tale 1 – A great saddle past its day

Even covered in dust and mildew, the quality of this aged dressage saddle was unmistakable. The leather was still fine. I doubt it was donated because it was unsellable – classic English brands will always sell online, no matter how old  they are.

And yet closer inspection reveals why it’s important not to be blown sideways by the famous name and the still-soft leather.

It’s fairly easy to see what’s happened here. The tree is an English spring tree, made of laminated beechwood. The tree is ‘open’, meaning it isn’t solid right across the seat – this keeps it flexible. The reinforcing comes from fine metal strips along the length of the tree.

With repeated use over many years, the tree has twisted. This is most likely due to continual mounting from the ground, with the rider’s right hand pulling on the cantle. Or, it may simply have twisted due to being stored badly. Who knows? No matter: it would be damaging to a horse’s back now and a repair sadly isn’t viable.

Tale 2 – An Early Flexible Tree

Another saddle from the remaining heap caught my eye. The tree moved as if broken, but apparently this was an early version of a flexible tree jump saddle, around 50 years old. Interesting… you can see for yourself how flexible it was in this 5-second video (2.8 MB) – Flexible seat

My curiosity was certainly pricked and I just had to look at the tree. I hadn’t brought my craft knife, so I grabbed the next best thing – the scissors from the desk drawer – and got stuck in. At least I could remove the panels and pull it apart.

Inside was a surprise.

Unlike saddles that have wooden trees, this saddle had a tree with leather sections right where the rider’s seat would be. In other words, the tree was part-wood, part-leather. How curious – its fundamental structure was compromised by materials that behave in very different ways.

The aim had clearly been to provide the rider with a closer contact jumping experience. But… how? On landing?

The main problem was that the tree only flexed in one place: right at the front of the leather section. The wooden section at the front was obviously rigid, so as soon as the forces reached a weaker area, in the form of the leather sections, it bent dramatically.

And wherever anything bends suddenly, there’s an inevitable pressure point. You can see the crease right across the seat in this photo. The only way it would make any kind of sense would be if the saddle were sat well forward on the scapula, so that the bend occurred in the lowest part of the back, just behind the withers. But again, why?

If you’re interested in a closer look, here’s the saddle once taken apart, being flexed manually. I was doing it one- handed, so forgive the camera movement (14secs, 7.1 MB) – Flex-tree-opened-up

Donating used saddles is still a go, though

Saddle design has changed enormously in the past decade. Newer saddles, particularly the adjustable brands, are incredibly useful to riding charities.

I guess the touchstone is this: Riding for the disabled associations care about their horses’ back health just as much as we do. Let’s donate equipment that we’d be happy to use on our own horses.

Please support your local center.

 

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