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VETERINARY

The On-going Effort to Minimise the Rate and Impact of Fractures

VETERINARYWeb Master

Published in European Trainer, January - March 2018, issue 60.

In thoroughbred racing, musculoskeletal injury is a major safety concern and is the leading reason for days lost to training.  Musculoskeletal injury is the greatest reason for horse turnover in racing stables, with financial implications for the owner and the racing industry. Injuries, particularly on race day, have an impact on public perception of racing.  

Upper limb and pelvis fractures are less common than lower limb fractures, but they can lead to fatalities. Reducing the overall prevalence of fractures is critical and, at the very least, improving the rate of detection of fractures in their early stages so the horse can be withdrawn from racing with a recoverable injury will be a big step forwards in racehorse welfare. Currently, we lack information on the outcomes following fracture, and an article recently published in the Equine Veterinary Journal (EVJ) from the veterinary team at the Hong Kong Jockey Club (HKJC) addressed this important knowledge gap.

Hong Kong Fracture Outcome Study

The HKJC veterinary team is in a unique position to carry out this work because their centralised and computerised database of clinical records, together with racing and retirement records, allows them to document follow-up, which is all but impossible elsewhere in the world. Dr Leah McGlinchey, working with vets in Hong Kong and researchers from the Royal Veterinary College, London, reviewed clinical records from 2003 to 2014 to identify racehorses that suffered a fracture or fractures to the bones of the upper limb or the pelvis during training or racing, confirmed by nuclear scintigraphy, radiography, ultrasonography, or autopsy....

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Getting to Grips with Strangles: Working Together to Break the Strangles-hold

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Published in European Trainer, January - March 2018, issue 60.

Strangles, caused by a bacteria called Streptococcus equi, is one of the most frequently identified infectious diseases of horses worldwide. More than 600 outbreaks of Strangles are diagnosed in the UK each year. Infected horses typically develop fever followed by abscesses in the lymph nodes of their head and neck.

These abscesses are painful and the affected horses will often lose their appetites and become depressed. Some horses can be badly affected during an outbreak and the disease kills around one in a hundred animals. The bacteria can spread quickly through yards via contaminated drinking water, food, tack, equipment and people. Some outbreaks can involve all of the horses on a yard and all outbreaks require movement restrictions that usually remain in force for over two months. Consequently, Strangles is responsible for considerable economic and welfare cost. This article will provide an update on the progress being made towards eradicating Strangles and highlight what we can each do to keep our horses safe.

An age-old problem:

Strangles was first described in 1251 by Jordanus Rufus, a knight of Emperor Fredrick II. The disease was seen as inevitable and better for horses to fall ill sooner rather than later to get the disease over and done with. In 1811 Napoléon, Emperor of France, wrote a letter to request that the 543 horses being sent to his army should be “at least 60 months of age and should already have recovered from Strangles” so that they would be less likely to fall ill from this disease on the battlefront. More than 200 years later, many people still believe that it is inevitable that their horse will suffer from Strangles sooner or later. However, we understand so much more about the disease today and really can significantly reduce the risk of horses falling ill...

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A report from the Merial - Performance Horse CPD and Raceday at Gowran Park

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Becky James BSc, MSc - Haygain

 

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Vets from all over Ireland congregated at Gowran Park racecourse in July for a continuing professional development event on the Performance Horse. The event, organised by European Trainer Magazine and Merial Animal Health, was the second in a series of veterinary CPD events for 2017 and featured a panel of expert speakers. The event was co-sponsored by Haygain and Connolly’s RED MILLS. 

Managing Inflammatory Airway Disease – Dr Emmanuelle Van Erck-Westergren

The first speaker Dr Van Erck-Westergren was due to fly in from Brussels on the morning of the event, so when her flight was cancelled at the last minute there was a moment of concern for the organisers but they arranged to bring her into the room via a video link so all was not lost!

Using her experience in practice at the Equine Sports Medicine Practice in Belgium, Dr Van Erck explained the importance of vets helping clients to manage the environment of the horses to prevent and manage Inflammatory Airway Disease (IAD). She described managing the horse’s environment to reduce exposure to noxious inhalable particles and improve hygiene and ventilation in the stable as the cornerstone to the success of treating IAD.

Important considerations for the environment include building design, bedding, stable activities and most critically, the forage, as this is in the horse’s breathing zone. Dr Van Erck explained that hay remains an important source of forage for horses but it is also a major source of dust and contaminants. Soaking hay is a cheap way of reducing airborne dust but it promotes bacterial proliferation and leaches out the nutritional value so well-made haylage or preferably steamed hay should only be fed to horses with IAD.

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Epiduroscopy: an exciting window into back pain in horses

VETERINARYWeb Master
  Back pain is a well known cause of lameness, gait alterations and poor performance in sport horses. Up to 25% of dressage horse owners report back problems in their animals, but not only sport horses are affected. Although racehorses compete at a younger age than other equine athletes, they might suffer from back pain more often than we think, autopsy studies have identified pathological changes in the back of the majority of examined young thoroughbreds. Until recently, it has been very difficult to investigate back pain and it is easy to overlook this as a cause of disappointing performance. A novel surgical technique which has recently been reported in Equine Veterinary Journal, may change all this.      an adult racehorse of average size, the complete sacral, lumbar and a small part of the thoracic spinal canal can be reached with a 60 cm endoscope.      How can epiduroscopy help veterinarians to find the source of pain in a horse with back problems?     While the spinal cord sends and receives signals directly from the brain, the spinal nerves are the communication pathway between the spinal cord and the body. Spinal nerves are, among other things, responsible for the movements of the muscles in the back and legs and for sending information about pain in the back and legs back to the brain. Injury to a spinal nerve can result in dysfunction of muscles or in pain. Fortunately, the spinal nerve roots are well protected from injury, first by the surrounding bony vertebrae and, after leaving the spinal canal, by a thick muscle layer. However, the nerve can be injured at the point where it exits the spinal canal. The spinal nerves exit the canal through the openings between two adjacent vertebrae. The opening is called the intervertebral foramina. Each opening is in close proximity to the facet joints that connect the vertebrae. Inflammation of these joints (facet joint arthritis) causes back pain and results in irregular growth of bone around the arthritic joint.        While severe bony changes can be picked up on radiographs, subtle changes can easily be missed. Unfortunately, even relatively small bony growths can impinge on the passing nerve and cause irritation and inflammation. Nerve root impingement is a recognized cause of lower back and leg pain in people and now that we have epiduroscopy available for horses, it will be possible to identify the prevalence and importance of this condition in equine athletes.  This will be especially interesting for young racehorses, where facet joint arthritis can be found in the thoracolumbar spine of up to 97% of cases that undergo autopsy but currently there is no information about the effects of this arthritis on passing spinal nerves.     << Fig 7 near here>>           Will epiduroscopy lead to better treatments?     Epiduroscopy can not only identify an inflamed nerve root, it can also be used to treat the inflammation through targeted injections of steroids via the working channel of the endoscope. There is a lot more work to do before this approach becomes commonplace for back pain. However, at North Carolina State University, the approach has used epiduroscopy to diagnose and successfully treat nerve root inflammation in the neck of an adult horse with chronic forelimb lameness. With help of the recently described lumbosacral epiduroscopy, it is now also possible to introduce this approach for therapy for inflammation in the spinal nerves located in the lower back. At North Carolina State College of Veterinary Medicine, we are currently developing a protocol to identify horses with back pain and unknown causes of hindlimb lameness that are suitable candidates for lumbosacral epiduroscopy. The findings of these examinations should shed more light on unknown or underestimated causes of back and leg pain in horses.          Back pain is a common and well-recognised problem in sport horses and may be an underestimated reason for poor performance in young racehorses. Autopsy findings suggest that especially young thoroughbreds frequently suffer from lesions in the muscles and joints of the lower back, but diagnosing these abnormalities is difficult in living horses. Some cases     << EVJ logo near here>>        The trouble with back pain     In people, “lower back pain” is the most common cause of job-related disability and a leading contributor to missed workdays, and it could be an underestimated problem in horses. Although several studies have shown a high incidence of pathology in the equine backbone, more correctly called the thoracolumbar and lumbosacral spine, and most of these findings were made during autopsies and not in clinical cases or live horses. Diagnosing the reason for back pain in a living horse is difficult, this is due to the complex anatomy of the horse’s back and the large size of an adult horse. The currently available diagnostic tools often fail to accurately identify the source of pain in clinical cases, the heavy back musculature limits the value of x-rays, while the wide range of scintigraphy (bone scan) findings in healthy horses makes it difficult to distinguish normal variations from clinically relevant problems. Ultrasonography for detecting bony anomalies in the equine back is also of limited value.       In people, the diagnostic tools of choice are magnetic resonance imaging (MRI) and computed tomography (CAT Scan, CT). But currently, because of the large size of adult horses, these tools cannot be used to assess the equine back. Consequently, veterinarians are often unable to pinpoint the underlying lesion in horses with clinical signs of back pain and thus cannot develop a targeted treatment plan.         Trainers will be familiar with the principles of endoscopy as it is a procedure commonly used to assess the upper airway and to perform minimally invasive procedures in joints (arthroscopy) or the abdomen (laparoscopy), also known as keyhole surgery. In people, endoscopy is also applied to identify problems within the spinal canal that can cause chronic back pain.         Anatomy of the back     The spine is a “column of vertebrae”, hence the scientific name “vertebral column”, that provides the bony support for the neck and back. In horses, the vertebral column is typically formed by 54 vertebrae that are connected to each other by joints, muscles and ligaments.  Although slight variations of these numbers are common, typically, in the neck there are 7 cervical, in the back there are 18 thoracic, 6 lumbar, and 5 sacral vertebrae; and, in the tail, there are 18 (15-21) caudal vertebra.         <<Figure 1 near here>>         The lumbar vertebrae are connected to the “sacrum”, a bone formed by the fused sacral vertebrae. Both the lumbar spine and the sacrum should be included when examining a horse with lower back pain. Within the spine, a central canal spans from the head to the tail. This spinal canal contains the spinal cord and the roots of the large nerves that originate from the cord (spinal nerves). The spinal cord and the nerve roots are the pathway for transmission of information, in both directions, between the brain and the rest of the body. To protect this delicate nervous tissue, the spinal cord and nerves are enclosed in a protective layer, the dura mater. Located between the dura mater and the bone of the vertebrae is the epidural space, which is filled with loose connective tissue and fat. Through small gaps between certain vertebrae (e.g. between the first and second cervical vertebra or the sacrum and the first caudal vertebra), the epidural space can be accessed and explored with a thin, flexible endoscope. This procedure is called “epiduroscopy” and allows a direct viewing of the structures in the spinal canal.        Epiduroscopy     Epiduroscopy is used in people to, among other things, diagnose injury and compression of the spinal cord and the spinal nerves. In horses, the cervical spinal canal, located in the neck, and the lumbosacral spinal canal, situated in the lower back, can be examined with epiduroscopy. While anaesthesia is required to examine the neck, lumbosacral epiduroscopy is done in standing, sedated horses.      A specialised endoscope set-up is required and since sterility is critical, epiduroscopy should only be performed in referral hospitals. The instrument has to be long enough to allow examination of the complete lumbosacral spinal canal and thin enough to fit into this narrow space. Ideally, the endoscope is at least 60 cm long but no thicker than 4 mm      <<Figure 2 near here>>.         The epidural space is entered through a small gap between two vertebrae, just above the base of the tail (Figure 3). The endoscope is then slowly inserted while the surgeon injects small amounts of a sterile saline solution through its working channel (Figure 4). This is necessary to push the epidural fat and connective tissue gently out of the way and allow viewing of the structures of interest, as shown in (Figures 5 and 6): the spinal cord and spinal nerves (enveloped by the dura mater), blood vessels and the inside of the surrounding vertebrae. In can be diagnosed with the currently available diagnostic tools, including a thorough clinical examination, radiographs, ultrasound and bone scan. In cases where these methods have been exhausted and failed to provide a diagnosis, epiduroscopy might provide the missing piece of information.            Legends     Figure 1: Horse skeleton seen from above, outlining the different regions of the spinal column.        Figure 2: Tip of a flexible videoendoscope that is suitable for lumbosacral epiduroscopy. The instrument is 60 cm long and has an outer diameter of 3.8 mm (Olympus BF-C 160).     Figure 3: This horse has been draped for lumbosacral epiduroscopy. The site where the endoscope will be inserted is left uncovered and has been prepared for aseptic surgery.      Figure 4: With his right hand, the surgeon slowly inserts the endoscope through a white plastic sheath into the epidural space. With his left hand, he controls the moveable tip of the endoscope. In the background, the monitor depicting the endoscopy image can be seen (out of focus).      Figure 5: Prior to injection of sterile saline through the working channel of the endoscope, the ability to see the different anatomical structures in the epidural space is very limited. At the bottom of the image, the dura mater that covers the spinal cord can be seen, while the epidural fat (on top of the dura mater) prohibits viewing of other structures.     Figure 6: Following careful injection of sterile saline solution, the examination becomes more rewarding. A spinal nerve root (*) can be seen emerging from the spinal cord (covered by dura mater) and cross the epidural space. Epidural fat can be seen above (x).      Figure 7: Pipe cleaners have been inserted into the intervertebral foramina, the opening between adjacent vertebrae through which spinal nerves exit the spinal canal. Note the close proximity of the facet joints (arrowheads).         Video 1: Preparation and insertion of the endoscopy in a sedated horse.      If you would prefer to include a link to this video currently it can be found at: http://onlinelibrary.wiley.com/store/10.1111/evj.12591/asset/supinfo/evj12591-sup-0001-Item1.mp4?v=1&s=735ecdd6a1606af5023c32d0406c01ef5e6f2445        Video 2: Lumbosacral epiduroscopy in a healthy horse.      If you would prefer to include a link to this video currently it can be found at:     http://onlinelibrary.wiley.com/store/10.1111/evj.12470/asset/supinfo/evj12470-sup-0002-MovieS1.mov?v=1&s=188211909de8842a9c434f5d202e2e76d53690

Dr Timo Prange

Read full study online here: 2016 Jan;48(1):125-9. doi: 10.1111/evj.12470

 

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Back pain is a well known cause of lameness, gait alterations and poor performance in sport horses. Up to 25% of dressage horse owners report back problems in their animals, but not only sport horses are affected.

Although racehorses compete at a younger age than other equine athletes, they might suffer from back pain more often than we think, autopsy studies have identified pathological changes in the back of the majority of examined young thoroughbreds. Until recently, it has been very difficult to investigate back pain and it is easy to overlook this as a cause of disappointing performance. A novel surgical technique which has recently been reported in Equine Veterinary Journal, may change all this.  

How can epiduroscopy help veterinarians to find the source of pain in a horse with back problems?

While the spinal cord sends and receives signals directly from the brain, the spinal nerves are the communication pathway between the spinal cord and the body. Spinal nerves are, among other things, responsible for the movements of the muscles in the back and legs and for sending information about pain in the back and legs back to the brain. Injury to a spinal nerve can result in dysfunction of muscles or in pain. Fortunately, the spinal nerve roots are well protected from injury, first by the surrounding bony vertebrae and, after leaving the spinal canal, by a thick muscle layer. However, the nerve can be injured at the point where it exits the spinal canal. The spinal nerves exit the canal through the openings between two adjacent vertebrae. The opening is called the intervertebral foramina. Each opening is in close proximity to the facet joints that connect the vertebrae. Inflammation of these joints (facet joint arthritis) causes back pain and results in irregular growth of bone around the arthritic joint.

While severe bony changes can be picked up on radiographs, subtle changes can easily be missed. Unfortunately, even relatively small bony growths can impinge on the passing nerve and cause irritation and inflammation. Nerve root impingement is a recognized cause of lower back and leg pain in people and now that we have epiduroscopy available for horses, it will be possible to identify the prevalence and importance of this condition in equine athletes.  This will be especially interesting for young racehorses, where facet joint arthritis can be found in the thoracolumbar spine of up to 97% of cases that undergo autopsy but currently there is no information about the effects of this arthritis on passing spinal nerves.

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Tendon function and failure: Recent advances

VETERINARYWeb Master
  Tendon injuries continue to be one of the most problematic injuries that affect racehorses. One of major issues facing veterinarians and trainers is that we have little understanding of why tendons become injured in the first place, how such the SDFT in the horse acts like the spring of a pogo stick, stretching and storing energy as a horse lands, and releasing energy to aid a horse’s locomotion as the limb pushes off.        There is a lot of clinical and research focus on these “energy-storing” tendons (such as the equine SDFT), as it is these tendons which are most prone to injury, and it appears to be a property of the function of such high strain, elastic tendons which result in these significant injuries will lead to so much economic loss and welfare issues for the affected horses. Under such extreme mechanical demands, it is not surprising the SDFT is prone to overuse injury, particularly amongst racehorses. SDFT injuries are highly debilitating, requiring considerable rehabilitation periods and are often career-limiting.        There is little convincing evidence of efficacy for any current treatment, and even after extensive periods of rest and rehabilitation, re-injury rates are extremely high, with little knowledge of how best to safely reintroduce training.  In the horse, tendons are also extremely long, due to the length of a horse’s leg. In the horse’s forelimb, there is no muscle lower in the leg than the level of the knee (carpal) joints, and tendons mainly extend from the level of the knee down to the hoof.       To understand why tendons, such as the equine SDFT, become injured and how we may develop methods to allow better treatments, we and other researchers, have been developing an understanding of how elastic “energy-storing” tendons function and how do they fail. We have recent, exciting data which leads us to believe that tendon injury occurs because of ageing or damage within a specific part of the tendon structure called the interfascicular matrix (IFM). The IFM is also known by some people as “the endotenon”.     Tendon is like braided rope, with the IFM connecting the rope strands laterally. Our evidence shows that the IFM is both stretchy and lubricating to allow the rope strands to slide around relative to each other, but as a tendon ages or becomes damaged, this mechanism does not work as well. Separately, we have shown that tendon overuse causes damage and inflammation in the IFM. Combining these results, leads us to think that the changes in the IFM with age cause damage to occur more easily to this region and this leads to tendinopathy.    The main molecule which makes up tendons are long rope-like proteins called collagens. In particular, in tendons, a specific collagen (Collagen-I) is bundled together into ropes of many thousands of collagen fibres and fibrils to ultimately form tendon structures known as fascicles. Fascicles are like individual strands or threads which make up a rope and are approximately half a millimetre in diameter. If a cut tendon is examined at post-mortem, it has a honeycombed liked appearance which are the individual fascicles, with the IFM surrounding each fascicle (Fig 1). Interestingly, when we use ultrasound to examine a tendon as part of a clinical examination, the fascicle is the smallest part of the tendon which we define ultrasonographically, and the presence of ordered fascicles is a good sign for tendon health (Fig 2)    Historically, the collagen which makes up the majority of a tendon has been the major focus of interest when it has come to trying to understand why tendons are so commonly injured, and why they never heal particularly well following injury. However, the central role of collagen to tendon function has been recently questioned. Undoubtedly, this molecule is important to tendons, but whilst the collagen material in a tendon has a major role in providing structural strength to a tendon, it has only a minor role in allowing a tendon to perform as an elastic structure. The collagen molecules which make up most of the tendon are like large metal reinforcing rods which are used when constructing large buildings. They give a lot of the strength to the material, but don’t fully effect the functional properties of a tendon. Another aspect of the collagen in tendon is that it is an extremely long-lived molecule and through life is hardly turned-over, so the body has very little capacity to repair and early damage. Research has shown that the half-life of a collagen molecule in a horse tendon is probably well over two hundred years, meaning that most horses will not repair or replace most of the collagen in their tendons between the time they stop growing, to the point that they die. The unique properties of the equine SDFT, which in part makes the horse such a superb athlete, are due to its elastic structure.       These elastic properties of tendon derive almost entirely from the IFM, which contains a lot of specialised molecules which both allow low-friction sliding between the collagen fascicles (proteoglycans) as well as specialized molecules, which allow elastic recoil. In the horse, this part of the tendon is uniquely adapted to both allow tendon extension and recoil, as well as withstanding multiple cycles of loading which would occur with fast galloping exercise over considerable distances.       Interestingly, it has been shown in a number of different studies that older horses are at increased risk of tendon injury. Coupled with this finding is the discovery that the IFM in older horses loses its ability to slide and extend as easily, and also loses its elasticity to some extent. Also this part of the tendon in older horses becomes less able to withstand the repeated loading which comes with fast galloping exercise, and as a consequence, is more likely to become damaged with repeated loading. Overall the IFM in older horses is stiffer, meaning that the collagenous tissue in tendons is likely to become loaded at an earlier part of weight bearing at the gallop, leading to a greater likelihood of overall tendon injury.       Another recent research finding is that when a tendon is subjected to repeated loading, analogous to the loading a tendon may receive during galloping exercise, is that early damage is seen to occur specifically in the IFM, and as a consequence the cells present in the IFM respond and produce an inflammatory response (like a local bruise) as a consequence of this damage. Thus the IFM tendon is not only important for the elastic function of the tendon, but there is now evidence that the earliest stage of injury probably starts in this part of the tendon.    As mentioned earlier, one of the problems with tendon injuries is that the tendon does not heal appropriately post-injury. The tendon heals by forming a scar tissue, which whilst often very mechanically strong, is a much stiffer and much less elastic than normal tissue. Hence an injured tendon is often mechanically very different from a normal tendon, even once healing is complete. There is often a marked discrepancy in the elastic properties of the normal tendon and the scarred tendon tissue, and it is at the interface between the two different tissues that re-injury occurs during a horse’s future racing career. We have observed that one of the major issues with the scarred tendon repair tissue is that it totally fails to reform any structure which is like an IFM (Fig 3); hence repair tissue in tendon is unable to extend and work elastically, and this is probably one of the main reasons why tendon repair is currently inadequate.     Through understanding these mechanisms of tendon function and failure, it opens up the possibilities in the future to make progress in both preventing and treating tendon injuries in a more optimal manner. Using current imaging technology, this understanding identifies the importance of the fascicular and IFM structure, which can be currently imaged using ultrasound, and emphasises the importance of identification of reformation of this structural appearance in injured horses before they are allowed to undergo fast work again after injury (Fig 2 & 4). It also identifies the need to develop better imaging methodologies which could be used to assist diagnosis and management of tendon injuries. An example of this is high-field MRI, which currently in the research laboratory allows exquisitely detailed imaging of the key tendon structure (Fig 5). There is also the potential for development of novel ultrasound imaging technologies which will allow dynamic measurement of sliding of the fascicles and potentially both identify tendons at altered risk of injury, as well as assisting with the rehabilitation of injured horses whilst they return to work. Such technology is being developed in our laboratories at the moment through generous support from the Horserace Betting Levy Board in the UK. Regenerative therapies need to be developed which specifically target regeneration of the IFM, as we think recreation of the IFM organisation is key to long term healthy tendon function following injury.     Finally, we need to understand how the properties of tendons develop as a foal grows to discover  whether we can intervene at this stage to allow formation of a healthier, less injury-prone tendon. We have evidence that the IFM undergoes considerable adaptation during the initial development and weanling stage of growth.    It is an exciting time for understanding tendon injury, its treatment and its prevention in the horse. We are now much closer to understanding the biological causes of this frustrating condition, and this gives us the potential to really make major advances in the next 5-10 years, which will be of substantial benefit to the horse.
 

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Gallery

Tendon injuries continue to be one of the most problematic injuries that affect racehorses. One of major issues facing veterinarians and trainers is that we have little understanding of why tendons become injured in the first place, how such the SDFT in the horse acts like the spring of a pogo stick, stretching and storing energy as a horse lands, and releasing energy to aid a horse’s locomotion as the limb pushes off.

There is a lot of clinical and research focus on these “energy-storing” tendons (such as the equine SDFT), as it is these tendons which are most prone to injury, and it appears to be a property of the function of such high strain, elastic tendons which result in these significant injuries will lead to so much economic loss and welfare issues for the affected horses. Under such extreme mechanical demands, it is not surprising the SDFT is prone to overuse injury, particularly amongst racehorses. SDFT injuries are highly debilitating, requiring considerable rehabilitation periods and are often career-limiting.

There is little convincing evidence of efficacy for any current treatment, and even after extensive periods of rest and rehabilitation, re-injury rates are extremely high, with little knowledge of how best to safely reintroduce training.  In the horse, tendons are also extremely long, due to the length of a horse’s leg. In the horse’s forelimb, there is no muscle lower in the leg than the level of the knee (carpal) joints, and tendons mainly extend from the level of the knee down to the hoof.

To understand why tendons, such as the equine SDFT, become injured and how we may develop methods to allow better treatments, we and other researchers, have been developing an understanding of how elastic “energy-storing” tendons function and how do they fail.

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The Biome of the lung

VETERINARYWeb Master

Dr Emmanuelle van Erck – Westergren, DVM, PhD, ECEIM

Equine Sports Medicine Practice (www.esmp.be)

Published in European Trainer October - December 2017, issue 59.

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Of bugs and horses

A couple of weeks ago, I was on an emergency call to a training yard. Half of the horses had started coughing overnight, some had fever and, as you’d expect when bad karma decides to make a point, the two stars of the premises due to face their greatest challenge to date the following  week, were dull and depressed. A thick and yellow discharge was oozing from their noses. It was not long before the yard became the typical scene of a bad strangles nightmare. The bacteria involved in strangles outbreaks are Streptococcus equi equi, highly aggressive and contagious germs, that spread fast and cause disruption in days of training and mayhem in tight racing schedules.

So what inevitably comes to mind when you hear the words germs or bacteria? No nice and friendly terms. As veterinarians, we have been taught that microorganisms are responsible for an endless list of gruesome diseases and conditions: abscesses, pneumonia, septicaemia ... you name it. They need to be identified and eradicated. Thank heavens; we still have an arsenal of antibiotics to get rid of the damn bugs. But recent research in human “microbiome” is making us think twice, especially as we aim to hit hard and large with antibiotics.

Never alone

Your healthy and thriving self, likewise your horse, host millions and trillions of bacteria. The “microbiota” is that incredibly large collection of microorganisms that have elected you and your horse as their permanent home. The microbiota is constituted not only by an extremely diverse variety of resident bacteria, but also by viruses, fungi and yeasts that multiply in every part of your external and internal anatomy. The discovery of this prosperous microbial community has triggered fascinating new research. It has unveiled the unsuspected links that exist between health, disease and the microbiota. In simple words, these microorganisms are vital to your strength and healthiness.

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The importance of identifying lower and upper limb lameness

VETERINARYWeb Master
  In thoroughbred racing, injuries to the limbs are a major welfare and safety concern and are the leading reason for horses to be out of training. Lameness is the number one reason for a high turnover in racing stables and, as many trainers know, it has huge financial implications for the owner, trainer, and the racing industry in general. Previous investigators have found that just over 50% of horses in training in England and Germany experience lameness during training and approximately 20% of horses in the UK suffer lameness that prevents them from returning to training. With this amount of horses on lay-up, it can be difficult to run a profitable racing stable.         In addition to having an impact on the horse’s welfare and future career, severe musculoskeletal injury also poses a serious safety concern for jockeys. The main reason for a jockey to suffer injury in a race is a horse sustaining a catastrophic injury or sudden death.  Researchers in the US found that a jockey was 171 times more likely to be injured when a horse they were riding in a race died. In thoroughbred racing, the most common life-threatening injury to horses involves fractures of bones in the fetlock. Therefore, the best way we can improve safety and welfare of both horses and jockeys is to highlight risk factors for fractures in an attempt to prevent these catastrophic injuries from occurring.         While the majority of injuries occur in the lower limb, such as condylar fractures or suspensory/tendon injury, up to 30% can occur in the upper limb. Several colleagues and I have recently investigated fractures of the upper limb and pelvis in racehorses at the Hong Kong In addition to the welfare of the horse and jockey, severe injuries that occur on race day have an impact on the public perception of racing. This is becoming more apparent in recent times, with an increasing number of animal right activists and the wide availability of social media. It is unknown in the future if certain races will be banned and emphasises how important research in this field is to decrease the number of these fatal injuries.         Jockey Club (HKJC). Although these fractures are less common, they still pose a serious risk when they occur. These include fractures of the radius, humerus, scapula, tibia, femur, and pelvis. These bones are very large and considering the weight of the average racehorse, once a complete fracture of these bones occur there is limited chance of repairing them. It has been demonstrated by previous researchers that these fatal injuries are often the end result of a repetitive or stress-related injury. Therefore, if we could identify these horses during training before they develop a complete fracture we may be able to prevent these fatalities.         Fractures of the upper limb and pelvis can affect horses in numerous different ways. Typically, if a horse has sustained a stress fracture it shows as a severe lameness following fast work, and it improves with rest. However, sometimes these stress fractures can present as a mild lameness with an insidious onset, making it difficult for trainers or riders to observe. As a result, these early injuries can often be mistaken as something less serious, such as a sore foot. Not only is it difficult for the trainer and rider, these cases of lameness are often not straightforward for the veterinarian either. As a result, multiple tools such as radiographs, ultrasound, and bone scan may be required to make a firm diagnosis.         To understand this concept, it is important to understand the mechanism of bone injury. This is similar in both horses and humans. Bone is a versatile structure composed of minerals, collagen, and water. The minerals provide stiffness and strength to the bone, while the collagen and water make it tough and give it a degree of elasticity. Although we do not associate elasticity with bones, if they did not have this property they would be extremely brittle and break very easily.          There are a few important cells in bone that are worth mentioning. Osteoblasts help build new bone and osteoclasts help dissolve and remove old bone so that it can be replaced by fresh, healthy bone. When a lot of stress is placed on bone, such as in certain periods of race training, this stimulates a biological response to increase the size and shape of the bone and additional bone is formed in areas of stress (bone modelling). Also, repetitive loading of the bone, from regular gallops and races, can result in small cracks forming within the bone tissue. These microcracks can join together to form stress fractures. If no extra strain is placed on this bone these microcracks can heal; however, if work is continued this can result in a catastrophic fracture developing. It is a key point to note that during the microcrack formation a lameness may be evident. If the horse is rested at this point, the cells that break down the damaged bone (osteoclasts) cause bone resorption. This results in a temporarily weakness until the new bone is formed. Therefore, if the horse returns to work during this period of new bone formation he is at increased risk of developing a fracture. The resorption phase can occur in as quick as two weeks, but the formation of new healthy bone may take between two and four months, although this is not the same for every injury, every bone, or every horse. This means that if a horse is out of work for whatever reason for more than a few days, he may be at an increased risk of developing a fracture when put straight back into work.         Multiple researchers across the world have worked to identify risk factors that may predispose racehorses to developing a fracture. It must be considered that there are different racing and training regimes, racehorse surveillance programmes, and veterinary resources across racing jurisdictions, and therefore the risk factors may not be the same in every area. Sometimes conflicting results are found. Work from the UK suggests a detrimental effect on bone of the accumulation of long-distance workouts at slow speed and that there are potential benefits of the gradual buildup of high-speed exercise. In addition, short-distance, high-speed exercise has been shown to have a protective effect on skeletal injury.         There are many other risk factors to consider. Although not specifically looking at fractures, it has been shown that with increasing age, horses are at increased chance of sustaining a musculoskeletal injury that will prevent them from returning to racing. However, the risk for a fatal injury decreases with age. There are also certain injuries that are more likely in certain age groups, such as bucked shins and tibia stress fractures in two-year-olds and humeral stress fractures in three-year-olds. One would assume that this is associated with the development of the musculoskeletal system and its response to training regimes. The more we learn about this, the more aware trainers can become, such as, for example, knowing that a horse is more susceptible to bucked shins at a certain age and adjusting training regimes accordingly. There are numerous factors that have been found to affect the risk of injuries such as gender, quality of the race, hoof conformation, and racetrack surface. However, these factors are often inter-related in a complex manner, which often makes it difficult to accurately assess the risk posed by each individual factor. For example, it has been shown that the type of surface will affect the way that a horse lands and puts weight on his limbs, but the same horse doesn’t train on multiple surfaces for comparison. There will be different training regimes, shoeing practices, tack, riders, and weather conditions that will affect the way a horse will train. This makes training surfaces difficult to compare, and there are often confounding results.         In Hong Kong, we examined all of the racehorses in training over 11 racing seasons. Our aim was to find out what type of fractures of the upper limb they suffered, how many of these were fatal, how successful these horses were following fracture, and how this compared to the rest of the world. Our eventual goal is to look at risk factors in an attempt to help reduce the occurrence of injuries. The incidence of fractures of the upper limb and pelvis were low over this time period. There was a total of 102,785 starts in 8,147 races with most of these (90%) being on turf. In Hong Kong, horses typically start racing as three-year-olds rather than at two, and this may explain why we saw a greater number of fractures of the humerus compared to in the UK and US, where tibia fractures are more common. In most of the horses that developed a lameness it was obvious (grade 3 out of 5), but it is important to note that a large proportion of horses had a subtle lameness (grade 1 or 2). This is an important point, as horses in this bracket may have a very mild intermittent lameness that may go unnoticed. The lameness may typically improve with rest and then may form a complete fatal fracture during the next period of fast work. Therefore, as previously mentioned, careful attention must be given to horses that show even a mild lameness after fast work in order to obtain an accurate diagnosis and ensure that appropriate rest and treatment may be administered, if necessary. Lastly, we found that a large proportion of the horses that suffered from non-fatal fractures went on to lead successful racing careers after being given time to recover: 74% of horses with upper limb fractures went on to race again, and over half of these won a race.         In summary, fractures of the upper limb and pelvis are not as common as fractures and other injuries of the lower limb in racehorses. However, if lameness associated with this is not recognised early, these can develop into serious or fatal injuries. The more we research this topic the more we are learning about certain risk factors that may help decrease the occurrence of these injuries.

First published in European Trainer issue 58 - July - September 2017

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In thoroughbred racing injuries to the limbs are a major welfare and safety concern and are the leading reason for horses to be out of training.

Lameness is the number one reason for a high turnover in racing stables and, as many trainers know, it has huge financial implications for the owner, trainer, and the racing industry in general. Previous investigators have found that just over 50% of horses in training in England and Germany experience lameness during training and approximately 20% of horses in the UK suffer lameness that prevents them from returning to training. With this amount of horses on lay-up, it can be difficult to run a profitable racing stable.

In addition to having an impact on the horse’s welfare and future career, severe musculoskeletal injury also poses a serious safety concern for jockeys. The main reason for a jockey to suffer injury in a race is a horse sustaining a catastrophic injury or sudden death.  Researchers in the US found that a jockey was 171 times more likely to be injured when a horse they were riding in a race died. In thoroughbred racing, the most common life-threatening injury to horses involves fractures of bones in the fetlock. Therefore, the best way we can improve safety and welfare of both horses and jockeys is to highlight risk factors for fractures in an attempt to prevent these catastrophic injuries from occurring.

Coverage of the Merial Raceday - York 2017

VETERINARYWeb Master
 Over 40 vets from around the UK attended the continuing professional development event titled ‘How to optimise  the respiratory effects on performance’ at York Racecourse this May. The event, organised by European Trainer  Magazine and Merial Animal Health, featured a panel of expert speakers and was co-sponsored by Connolly’s  RED MILLS & Foran Equine and Haygain. Louise Jones BSc, MSc attended the seminar and reports on the key  messages as follows.  Functional Significance of Upper Airway Obstructions - Dr Kate Allen  Dr Kate Allen, from Langford Vets, commenced proceedings, explaining that whilst upper airway obstruction  (UAO) is second to lameness as the most common cause of poor performance, it is difficult to quantify its  significance on athletic performance.  UAO is caused by a narrowing of the airways, often as a result of the collapse of the varying upper airway  structures. However, Dr Allen emphasised that it is a complex condition and in almost half of the cases involves  the concurrent collapse of multiple structures.  Horses suffering from UAO initially attempt to maintain airflow by increasing inspiration time and decreasing  respiratory frequency. However, if this is unsuccessful then the amount of oxygen available for the muscles to  work effectively will be reduced, resulting in impaired performance. The degree to which athletic performance is  affected, especially in the elite horse, will obviously depend on several factors, including:   The severity and complexity of the condition: palatal instability alone will only have a mild effect on  performance, but when occurring in conjunction with dorsal displacement of the soft palate (DDSP) the  impact will be significantly greater.   The duration of time the obstruction is present within a bout of exercise: DDSP at the end of a race is  likely to be less performance limiting than if it occurs during the early stages.   The work the horse is undertaking: arytenoid cartilage collapse (ACC) at low exercise intensity does not  significantly impact respiratory frequency, but at higher intensity exercise ACC will reduce respiratory  frequency.   Individual variation: the effect of DDSP on oxygen consumption can vary from as little as 0.1% up to  15% depending on the individual.  Dr Allen went on to examine the possible link between UAO, exercise induced pulmonary haemorrhage (EIPH)  and inflammatory airway disease (IAD). She stressed that whilst there is good scientific rational suggesting that  UAO may exacerbate EIPH by further increasing pressure differences between the inside of the capillary and the  alveolar, at present there is limited clinical data to support the theory. Likewise, there is minimal evidence to link  UAO and lower airway disease, although there have been occasional examples where treatment for lower airway  disease results in a reduction of abnormal respiratory noise.  Dr Allen stated ‘the winning horse is the one that slows the least’ and described how making a 1% improvement  to a horse finishing in fourth place would mean that they should then go on to win 50-75% of the time, in national  hunt and flat racing respectively. Dr Allen warned that any UAO in the racehorses is likely to have a detrimental  impact on performance. She also advised that the effects of certain conditions such as pharyngeal wall collapse  and severe medial deviation of the aryepiglottic folds may currently be underestimated. Dr Allen concluded that  whilst treatments for UAO may reduce the issue, unfortunately they are not always effective in restoring the  horse’s full respiratory capacity.  Key Aspects of Infectious Respiratory Disease - Professor Andy Durham  Professor Andy Durham, from Liphook Equine Hospital, discussed bacterial and viral causes of respiratory  disease in horses. He provided the veterinarians with a detailed review of the various diagnostic tools available  including visual assessment of the airways, bacteriology and haematology, particularly emphasising the  usefulness of testing serum iron levels as a marker of inflammation.  Professor Durham went on to question the clinical relevance of bacteria isolated from the nasal swabs and  tracheal washes. He recommends that bacteria isolated from nasal swabs should not be regarded with  pathologic relevance, unless accompanied by abnormal mucus, squamous epithelial cells and/ or greater than  20% neutrophils. In addition, he highlighted that evidence of bacteria from tracheal washes is often not  pathologically relevant and must be interpreted with caution. The potential for contamination during the scoping  procedure is a major confounding factor. Referring to cases of strangles, Professor Durham expressed the view  that using nasopharyngeal swabs to test for carriers is unreliable, even when these tests are repeated.  Therefore, he recommends guttural pouch lavage as a far superior method of identify carriers of Streptococcus  equi.  There are several viruses that can cause infection of the airways, potentially predisposing the horse to  inflammatory airway disease (IAD) including picornaviruses, herpesviruses and equine influenza virus.  Picornaviruses, include equine rhinitis virus A (ERAV) and equine rhinitis B (ERBV), cause mild respiratory  infection in horses, similar to the common cold brought about by rhinoviruses in humans. Although a significant  association between IAD and seropositivity to ERAV has been confirmed, the importance and role of equine  rhinitis viruses in poor performance remains unclear. Professor Durham questioned the sensitivity of the equine  rhinitis virus A and B blood test. He expressed surprise that only one out of 607 samples tested at the Animal  Health Trust last year was positive, even though subclinical infections are relatively common.  Of the herpesviruses known to infect horses EHV-1 and EHV-4 are the two that result in acute respiratory  infection. The relevance of EHV-2 and EHV-5 is less clear and Professor Durham stressed that positive EHV-2  blood tests must be interpreted cautiously as they may be indicative of previous exposure to the virus, rather  than current disease. He advised that nasal swabs may be more useful than serology as a diagnostic technique,  highlighted that EHV-2 has been isolated from the nasal swabs of horses suffering from IAD, suggesting that it  could play a role in aggravating the airways.  Professor Durham next discussed equine influenza. He explained that the equine influenza A virus (H3N8) is  diverged into two different strains - the European strain and the American strain. The latter is further divided into  the Kentucky strain and the Florida strains; clade 1 and clade 2. Drawing attention to a recent outbreak in the  north of England, Professor Durham stressed that equine flu caused by the Florida clade 2 virus, remains a  threat in the UK. He also warned that horses that are exposed to internationally travel should be vaccinated  against the Florida clade 1 virus, which has been detected in the USA. Professor Durham concluded his  presentation by questioning the efficacy of many of the equine influenza vaccines currently used in the UK,  emphasising that only one, Merial’s Proteq-flu, is effective against both clade 1 and 2 of the Florida sublineage.  Managing Inflammatory Disease - Dr Emmanuelle van Erck  The importance of the horse’s environment on respiratory health cannot be overlooked. It is unavoidable that  horses in training are housed indoors for much of their day, resulting in increased exposure to respirable dust,  ammonia and mould. Consequently, these horses will be at increases risk of IAD, although this may not always  manifest itself as a clear respiratory problem. Often the clinical symptoms of chronic respiratory issues can be  subtle but may include early fatigue, reduced recovery and an unwillingness to work. According to Dr  Emmanuelle van Erck’s own research 84% of the horses referred to a veterinarian for a regular health check,  poor performance or respiratory issues were suffering from IAD and she firmly believes that managing the  horse’s environment carefully is the ‘key to long-term management of IAD cases’.  Dr van Erck explained the crucial importance of stable design in facilitating correct ventilation, controlling  humidity and limiting exposure to potential noxious elements. She discouraged the use of ventilators and fans,  which simply exacerbate the dissemination of dust and mound spores. Likewise, she highlighted the risk of  storing preserved forage and bedding material within the stable building. To reduce the respiratory challenges  encountered by stabled horses, Dr van Erck also recommends that they are turned out when activities such as  mucking out or sweeping are taking place. She went on to explain that temperature within the stable environment  is also important, advising that horses are most comfortable at temperatures around 10 o C. She warned that our  tendency to close windows and doors during cold weather can create the warm, humid environment favoured by  harmful microorganisms.  When considering bedding material, although straw has several benefits, Dr van Erck reiterated that it can be  naturally contaminated with mould and fungi. Inhalation of these microorganisms can impact respiratory health  and research that has shown horses are 3.8 times greater chance of being diagnosed with IAD if fungi were  found in their airways. Paper or cardboard bedding material, which are lower in dust and other aeroallergens, are  preferred by Dr van Erck. Alternatively, she encourages the use of dust-free wood shavings, provided the flake  size and thickness is adequate. Another option is to use rubber matting, although this must be kept clean in order  to avoid fungal growth.  Forage, particularly hay, is another major source of dust and contaminants which can contribute to IAD. To  reduce this risk Dr van Erck prefers horses to be fed either commercially grown, quality controlled haylage or  steamed hay. She explained that soaking hay, although economical, is not advisable and could, in fact, create an  environment for bacteria to proliferate. Similarly, Dr van Erck warned against using home-made hay steamers,  which may not homogenously heat the hay to the temperatures needed to destroy bacteria and mould, and  therefore could exacerbate the issue by creating the ideal environment required for microbial incubation. Instead  Dr van Erck advised steaming hay, using a Haygain steamer, immediately prior to feeding. She described that  the heat generated in this commercially available steamer will kill the bacteria and reduce the respirable particles  by more than 95%, without affecting the nutritional value of the hay. This offers trainers a practical way of  providing their horses with clean forage and thereby helping to significantly decreased the risk of IAD.  Optimising Oxygen Uptake and Lung Function - Dr Shaun McKane  In the world of racing ‘time is money’ said Dr Shaun McKane, from Cotts Equine Hospital & Veterinary  Specialists. He went on to use the one inch winning margin of Neptune Collonges over rival Sunnyhillboy in the  2012 Grand National to emphasise that oxygen is the key in making the horse the ultimate athlete and ‘every  molecule of oxygen is important’. Dr McKane explained that relative to other species, horses have 2.5 times  more lung surface area and almost 20 times greater cardiac output than humans. In addition, splenic contraction  during exercise means that the horse have the ability to increase the volume of circulating red blood cell volume  by as much as 65%, resulting in a doubling of their oxygen carrying capacity.  Dr McKane asked the question – ‘what makes the average horse average?’ The answer - lack of ability,  inadequate training and/or a reduction in their maximum oxygen uptake, scientifically referred to as VO2 max.  Discussing the importance of optimal training Dr McKane explained that if you train sub-maximally, you will  perform sub-maximally. Regular, lengthy aerobic exercise will help to condition the horse by increasing  mitochondria numbers and muscle capillary density. However, this type of training will not be sufficient to  optimise the horses VO2 max, which is a high indicator of athletic potential and has been found to be highly  correlated with race times in thoroughbred horses. To achieve optimal VO2 max, high intensity ‘interval  training’ is essential, plus this type of training will also condition both the bones and tendons.  Dr McKane went on to discuss the potential detrimental impact of airway inflammation and EIPH on athletic  performance. He reiterated that whilst inflammation can promote EIPH it doesn’t necessarily cause it.  Nevertheless, he advises that care should be taken when recommending exercise for horses suspected to be  suffering from pulmonary inflammatory disease as they may be at greater risk of EIPH. Discussing the effect of  EIPH on performance Dr McKane highlighted that the degree of EIPH should be considered. He explained that  mild bleeding (grade 1-2 EIPH) will not affect performance, although more severe bleeding (grade 3-4) will  reduce athletic ability.  Dr McKane recommended routine monitoring of racehorses for signs of airway dysfunction by regularly carrying  out cytologic evaluation of tracheal washes or bronchoalveolar lavages. Carrying out these evaluations close to a  race will obviously be helpful in determining if the horse is ‘fit to race’ but Dr McKane’s preference would be to  undertake these tests 10 days pre-race, thus allowing sufficient time for steroid treatment and an adequate  withdrawal period. He also encouraged the use of pre-emptive testing on horses that are considered to be  performing well. In addition, Dr McKane highlighted that whilst resting horses suffering from EIPH may be  appropriate, extended periods off work (e.g. 3 weeks) would result in fitness returning to basal levels.  Finally, Dr McKane touched on seasonal aspects of respiratory issues, explaining that he has observed an  increase in issues around February-March, which could potentially be associated with an increase in fungal  growth as a result of warmer weather conditions. Another high risk period is March-May, which may be linked to  an increase in tree and rapeseed pollen as a similar pattern is observed in humans suffering from asthma.  Assessment of a novel antioxidant supplement for Thoroughbred horses in training - optimising and  protecting cells through nutrition - Maureen Dowling  Maureen Dowling from the School of Veterinary Medicine, University College Dublin (UCD), summarised her  research about using a natural antioxidant and fish oil supplement on horses in training.  She explained that oxidation is simply the production of volatile free radical atoms and is a completely natural  process necessary for all biological pathways. Oxidation can become detrimental to horses when the  antioxidant/oxidant equilibrium changes in favour of oxidants, otherwise known as free radicals. She explained  that horses have endogenous antioxidants, which can normally control oxidant production, however when a  stress factor is introduced, such as exercise, respiratory or inflammation response problems can arise. Free  radicals will bind onto the membranes of cells causing erosion to the membrane, leading to cell necrosis and  ultimately tissue damage. Antioxidants prevent this damage by binding to the oxidant before it gets to the cell or  within the cell. Natural sources of antioxidants such as bioflavonoids allow for immediately available antioxidant  properties.  Maureen Dowling described how unfit or pre-trained horses are more susceptible to muscle cell breakdown. In  her research Dowling has shown that supplementation with a natural antioxidant and fish oil supplement prior to  and throughout the training process allows a build-up of antioxidant protection before cells are affected. The  research carried out in UCD showed a significant reduction of creatine kinase (CK) levels in horses receiving the  supplement during the training regime. In addition, following 12 weeks of supplementation, horses had higher  levels of α-tocopherol than those not supplemented. Plus, following a maximum intensity treadmill exercise after  12 weeks of training, horses who didn’t receive the supplement had significantly higher levels of oxidation in their  blood than those that were on the supplement.  Unsurprisingly, give the calibre and expertise of all the speakers the seminar was a great success and instigated  numerous questions and discussions amongst the veterinarians in attendance.

First published in European Trainer issue 58 - July - September 2017

Click here to order this back issue!

Over 40 vets from around the UK attended the continuing professional development event titled ‘How to optimise the respiratory effects on performance’ at York Racecourse this May. The event, organised by European Trainer Magazine and Merial Animal Health, featured a panel of expert speakers and was co-sponsored by Connolly’s RED MILLS and Haygain. Louise Jones BSc, MSc attended the seminar and reports on the key messages as follows.

Functional Significance of Upper Airway Obstructions - Dr Kate Allen

Dr Kate Allen, from Langford Vets, commenced proceedings, explaining that whilst upper airway obstruction (UAO) is second to lameness as the most common cause of poor performance, it is difficult to quantify its significance on athletic performance.  

UAO is caused by a narrowing of the airways, often as a result of the collapse of the varying upper airway structures. However, Dr Allen emphasised that it is a complex condition and in almost half of the cases involves the concurrent collapse of multiple structures.

Horses suffering from UAO initially attempt to maintain airflow by increasing inspiration time and decreasing respiratory frequency. However, if this is unsuccessful then the amount of oxygen available for the muscles to work effectively will be reduced, resulting in impaired performance. The degree to which athletic performance is affected, especially in the elite horse, will obviously depend on several factors, including....

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