The Big 'C'

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Tibial Stress Fractures – More Common Than You Think

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Ten common skin conditions in racehorses, and how to treat them

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Barry Sangster and Phil Dyson (14 October 2009 - Issue 14)

Equine gastric ulcer syndrome

Equine Gastric Ulcer Syndrome (EGUS) is an increasingly common problem in the Thoroughbred racehorse, causing a range of symptoms from depression to aggression, and often impacting negatively on performance.

Diagnosis is sometimes difficult, although there are methods by which they can be swiftly identified and treated. Equine gastric ulcers are graded on a scale of 0 to 4 where 4 is the most severe. A grade of 2 or more is clinically significant and usually warrants treatment. The primary objectives of treatment of equine gastric ulcers are to facilitate healing and relieve symptoms.

This can be accomplished by the use of antacids, histamine receptor antagonists or acid pump inhibitors. Ulcers are an issue - especially for racehorses- as they can be a source of chronic pain, leading to reduced appetite, loss of condition and sometimes colic. The clinical signs of the problem are often intermittent, and can vary tremendously depending on the horse and the types of discipline they compete in.

Two types of tissue line the equine stomach. The bottom of the stomach is lined with a pink glandular mucosa which constantly produces concentrated hydrochloric acid, whilst protecting itself with a sticky mucus and bicarbonate secretion.

At the top, the squamous (or non-glandular) mucosa is found – this tissue has no useful role in the stomach as it does not produce acid nor any protective mucus - squamous mucosa is therefore very susceptible to acid injury.Racehorses are more prone to ulcers in the squamous mucosa.
 


A pairing of equine vets that regularly diagnose and treat equine gastric ulcers are Rachael Conwell and Richard Hepburn, who are based in England. Hepburn estimates that 80% of ulceration is found in the top part of the stomach and Conwell's experience in practice also supports this. She explains: "With increasing intensity of exercise, it is thought that acid splashes up to cause ulcers in the squamous region.

This can vary from low grade to quite significant degrees of ulceration". "Quite often there can also be glandular ulcers at the exit from the stomach into the duodenum so it's important to look here," says Conwell.

Hepburn explains: "Horses may exhibit poor exercise tolerance, be reluctant to gallop and have slower race times. Post-race heart rates are higher when ulcers are present." Conwell adds: "A problem with ulcers is that they can manifest as low grade colic or failure to maintain bodyweight, particularly in racehorses." They may also have reduced exercise tolerance, refuse to gallop, and have poor jumping performance.

Poor coat hair can be another indicator. "Generally trainers are pretty good at spotting the signs. They may notice that feed doesn't get cleaned up in quite the usual hungry way. They also know their horse's character and so will notice small changes in attitude. The horse might become more grumpy, look miserable, resent being groomed or having their girth done up.

Perhaps they are just not the happy horse they used to be. It can be as subtle as that."  "In some situations there are no outward signs at all, only that the horse's performance is reduced." Says Conwell. 

According to Hepburn, the incidence of EGUS may be up to 100% in racehorses, with ulcers most severe in horses that are in full training or have just raced. 
Conwell and Hepburn regularly use gastroscopy as a method of ulcer detection. Gastroscopy is a visual examination technique through which a veterinarian will assess the stomach health of an animal using an endoscope, determining the presence and severity of ulcers and monitoring the success of prescribed treatment. Moreover it is a non-surgical and relatively simple procedure which takes less than fifteen minutes.

The same kit can also be used for airway examinations looking at the larynx, trachea and bronchi for respiratory problems, and inside the guttural pouch to check for infections such as strangles. This is useful as it means horses do not need to be sedated on more than one occasion to assess both airway and stomach health. 

Using gastroscopy to diagnose ulcers is a relatively simple procedure. The horse is starved for 8 hours but is allowed free access to water. It is then given a short acting sedative, and an endoscope is passed up the nose, down the esophagus and into the animal's stomach.

The stomach is inflated with air using a pump attached to the endoscope and any food is washed off with water- squirted through the endoscope. Once the end of the endoscope is in the stomach, it can be ‘driven' by the vet using hand-held controls to move it up or down, to the left or right. In this way the inside wall of the entire stomach can be examined.

A key difference between regular endoscopy and the specialist gastroscopy kits now available is that there is 3m of length to enable full examination of the entire stomach. Endoscope diameter is another difference, with 9 or 11mm being better tolerated by the horse for gastroscopy work than the standard size of 13mm.

Conwell has been using a 3m video-endoscope for two years now for diagnosing and treating racehorses. She says "I don't normally scope all horses in a training yard, only the ones where there is a suspicion that gastric ulcers could be affecting them. That said, it's rare that we don't find any ulcers in the racehorses we investigate." 

Other methods of detecting ulcers within the digestive system, anywhere from the stomach to the intestinal tract, are also proving effective. Kits which allow the handler to test for blood in the feces of the horse, an indicator of possible ulceration, are becoming more widely available, and may be a cheaper and less invasive method of diagnosing digestive health issues. 

In treating gastric ulcers, most vets will turn to a licensed acid suppressant product for equine use.

Treatment will vary in duration and intensity depending on the individual case, taking into account a number of factors including severity of ulceration and importantly, the horse's training regime, as there is some evidence that treatment effectiveness of some medications vary when the horse is still in full work. Antacids (which neutralize acids in the stomach), omeprazoles in paste and suspension (which suppress acid production) and histamine receptor antagonists are commonly used to reduce symptoms, heal lesions and reduce the likelihood of future problems.

Acid suppressants fed once a day are an effective remedy, believes Conwell, who adds: "Alternatively, histamine receptor antagonists, such as ranitidine, can be used. I normally re-scope horses about four weeks after treatment. If the problem has resolved then I recommend a quarter dose of an acid suppressant to prevent recurrence of ulcers during training." 

Trainers often notice a character change in their horses once treatment is started, according to Conwell.

Hepburn reports that some owners are ‘amazed' at the difference in horses given treatment for their ulcers: "Even though they may have been performing well before, resolving the problem makes their performance consistently good."

In addition to prescribing medication, ulcers can be reduced and in some cases, totally resolved by changing the feeding and/or stabling routine. High grain diets and a limited access to forage - which buffers stomach acid - are a factor in the prevalence of EGUS in racehorses. Ideally, horses should be given more access to a selection of forages, just as they would in the natural wild.

Conwell and Hepburn both recommend putting several haynets up, some with hay and others with haylage, to allow the horse to browse for forage. 
Hepburn says: "Turning horses out every day may help, although ulcers are just as common in NZ racehorses that are trained from pasture. Interestingly, some ongoing Danish work has shown that giving horses the choice of staying in or going out can reduce stress and associated gastric ulceration."

Various feed supplements are also available which help to maintain digestive health, both in horses which have received treatment for ulcers and are recovering, and in horses showing no symptoms of ulceration, in order to lessen the chance of digestive problems.

This is especially useful where it is not possible to radically change management practices, such as with horses stabled at the racetrack.
Hepburn concludes: "Some horses are more prone to ulcers than others – hence the need to assess each individual case. Also some ulcers heal more quickly depending on their location in the stomach."

Rachel Queenborough
 (10 July 2008 - Issue 9)

Shockwave Therapy - uncovering new treatments

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Shockwave Therapy - uncovering new treatments

Doctors originally used shockwave therapy more than 20 years ago to disintegrate kidney stones in their patients, then learned that the therapy can also treat tendonitis, tennis elbow, heel spurs and other ailments. Equine researchers are still uncovering everything shockwave therapy can do for horses after it was initially and successfully used in Germany in 1996 to treat lameness. Shockwaves are high-pressure, low-frequency sound waves generated by a device outside the body and focused on a specific body site. When the shockwaves meet tissue interfaces of different densities, the energy contained in the shockwaves is released and interacts with the tissue, triggering natural repair mechanisms and stimulating bone formation and blood flow.

The shockwaves can lessen or eliminate pain and accelerate healing. New York trainer Rick Schosberg has a unique perspective on shockwave therapy. He’s used it on himself and his horses. “I’ve used it for myself for tennis elbow; it helped my elbow for 90 days,” Schosberg said. “With my horses I’ve used it a couple times on injuries and it did okay for minor injuries, soft tissue and saucer fractures. It probably knocked a third off the healing time but it’s expensive. You use it for at least three treatments over a month and a half, usually every two or three weeks. As long as it‘s not abused it’s okay. You can‘t run a horse within 10 days after you use it and you have to report it every time you use it (in New York) because it has an analgesic effect.” Shockwave therapy’s impact on horse racing could not have happened if it wasn’t developed for human patients first. And that happened by accident. During experiments with high-velocity projectiles, which were being used to smash ceramic plates, an employee at a company in Germany touched the plate at the very moment the projectile hit the plate. He felt something in his body akin to an electric shock, though measurements showed that there was no electricity present. That prompted German scientists to begin researching the possible effects of shockwaves on humans in the late 1960s. The first successful disintegration of a kidney stone in a patient by shockwaves was done in 1971. Fourteen years later, experiments were conducted regarding the effect of shockwaves on bones, leading to experiments on other parts of the human anatomy.

Today, shockwaves are the first choice of treatment for kidney and ureteral stones and has morphed into treatment for other medical conditions. Will equine medicine’s use of shockwaves follow a similar pattern? The first equine disease to be treated with shockwaves was proximal suspensory desmitis, an injury to the suspensory ligament which is a major cause of lameness. A year later, shockwaves were used on a horse with Navicular Syndrome, an ailment affecting the small navicular bone in a horse’s foot and the connecting ligament. The first use of shockwaves in the United States happened in 1998 with a horse with a distal hock joint and navicular pain. All the results were encouraging. “When we first started using it, it worked okay on lameness,” Iowa State University’s Dr. Scott McClure, DVM, a leading researcher of equine shockwave therapy, said. “At this point in time, it’s been well documented for tendon and ligaments.

A lot of people think it works for stress fractures. I think there are some joint applications which we’re learning more about. Soft tissue, too. It’s been shown to increase permeability of cell walls.” He believes that increased cell wall permeability could lead to drugs which are more effective attacking tumors. “There’s potential for a lot of applications,” McClure said. “I clearly don’t think we understand all of its uses.” There are two types of equine shockwave therapy: extracorporeal generated outside the body and focused on a specific area of a horse’s body, and radial pressure waves when an applicator is pressed on the horse’s body. “The two of them get lumped together, but they shouldn’t be,” McClure said. “They’re very different. Radial pressure waves have lower pressure and more shallow penetration.” According to Dr. Stephen Adams of Purdue University‘s Veterinary Teaching Hospital in a 2002 article, studies have shown that shockwave therapy is effective treating suspensory ligament disease, bowed tendons, ringbone, bone spavin, splints, fractured splint bones, sore backs, navicular syndrome and fractures not healing properly. “Initial studies show that about 75 percent of horses treated for these conditions show marked improvement following shockwave therapy,” Adams wrote, while noting that many conditions require a second treatment to produce optimum results. “Advantages of this treatment are that no drugs are used, and horses with chronic conditions such as bone spavin, chronic suspensory ligament disease and navicular syndrome can continue to exercise.

Frequently, improvement in lameness is achieved in horses where conventional treatments have failed. Shockwave therapy is used as an adjunct treatment for fresh injuries such as recent bowed tendons with the goal of reducing convalescent time and improving the outcome.” On its website, the University of Wisconsin-Madison’s Veterinary Medical Teaching Hospital suggests using shockwave therapy on horses suffering from: suspensory ligament injury, tissue calcification, fractures or joint ankyloses, fatigue injury to bone, back pain, navicular disease and bone exostosis.

McClure documented the effect of extracorporeal shock wave therapy (ESWT) on horses with unilateral forelimb lameness in a study he co-authored with Jessica Dahlberg, Richard Evans and Eric Reinertson which was published in the July 1st, 2006 issue of the Journal of the American Veterinary Medical Association. The study focused on five geldings and four fillies and mares with lameness.

Treatment by ESWT resulted “in a period of acute improvement in lameness severity that typically persists for two days. Thus, in horses undergoing ESWT, exercise should be controlled for a minimum of two days after treatment to prevent further injury.” The reason is that ESWT has an undeniable analgesic effect. “This has raised concerns that use of ESWT to treat musculoskeletal injuries in horses may, because of the analgesic effects, result in overuse of the injured limb, causing further injury to the affected part and posing a risk to treated horses and their riders,” the study said. “For this reason, racing jurisdictions in the United States and the Federation Equestre International have adopted regulations that require a 5-to-7 day period after treatment before the horse is allowed to perform.”

Regardless, the horseracing industry, one never known to embrace change and new products, has quickly come on board in using this non-invasive treatment on their horses. “Over the last five years, it’s dramatically increased,” McClure said. “The market is starting to saturate. There’s a lot of equipment out there. In 1988, I had the second machine in the country. I think the owners and trainers have taken the bit and run with it. They’ve been very aggressive with that.” Trainer Sanna Hendricks used shockwave therapy on her multiple stakes winning steeplechaser Praise the Prince after he suffered a soft tissue injury below the pastern while winning the 2003 Grade 1 New York Turf Writers’ Cup at Saratoga Race Course. “We used shockwave therapy on him, and he responded to it,” Hendricks said in an August 30th, 2004 story in the Blood-Horse. “I took the conservative approach with him. I gave him plenty of time to rest and recover and didn’t bring him back to training until February 5th with an eye on these races at Saratoga.” Praise the Prince not only made it back to the races at Saratoga, he won the 2004 Grade 2 A.P. Smithwick Memorial Steeplechase there as a nine-year-old. If that isn’t an endorsement for shockwave therapy, what is? But shockwaves should not be construed as a panacea.

Complications can occur with incorrect use, and McClure wrote, “The release of kinetic energy at interfaces of different acoustic impedances is crucial in planning ESWT. Shock waves must never be focused on gas-filled cavities like the lung or intestine.” Meanwhile, he’s back at work, doing new studies to see just what else shockwave therapy may help.

Osteochondritis dissecans - the development, causes and treatments of OCD

By Deborah Spike-Pierce, DVM
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One of the most common orthopedic problems encountered in young horses is osteochondritis dissecans (OCD).  This is of particular concern in the Thoroughbred industry, where horses are often bought and sold before maturation is complete and are expected to perform starting at a relatively young age.  There are many common sources of confusion surrounding this disease.  Deborah Spike-Pierce, DVM discusses research into the development, causes and treatment of OCD.

Development

In the most basic sense, OCD is caused by a disruption of the normal growth process of bone. It most commonly occurs in young fast growing animals such as large breed dogs, pigs and horses.  Normally, a cartilage framework in the growth plate at the end of a bone is slowly converted into bone as an animal grows.  If this ossification process is interrupted, the syndrome of OCD can result. There are three major stages of this disease, although the term OCD is commonly used to refer to all parts of the syndrome.  The first phase is osteochondrosis (OC), which is a disturbance of ossification of cartilage into bone resulting in excess retained cartilage.  If this retained cartilage results in inflammation of the joint, this stage is termed osteochondritis.  The inflammation may manifest itself clinically as joint distention or lameness.  Osteochondritis dissecans (OCD) is the stage where a portion of the retained cartilage loosens from the parent bone and forms a fragment.  The separated fragment may remain cartilage or it may ossify into bone.  It is the disturbance of this fragment that can cause the most severe clinical form of the disease by shedding debris into the joint, thus causing synovial effusion and lameness.  Not all horses that develop OC will go on to develop OCD.  In many cases, horses will have no clinical signs and areas of retained cartilage will go on to ossify normally as the horses grow with no long term consequences.

Many different parameters have been described as having an affect on the development of OCD. There is no apparent common denominator in OCD formation and the disease is multifactorial.  Nutritional imbalances, trauma, rate of growth, biomechanical influences as well as genetic predisposition have all been documented as potential causes.

Recent research on the relationship between nutrition and development of OCD have found multiple correlations.  It has been shown recently in the United States that the time of year can affect OCD rates due to spring and autumn peaks in the energy content of the grass.  In studies, horses fed diets with low copper, excess zinc, excess phosphorus and high digestable energy have all shown increased rates of OCD.  There has been an emphasis placed on copper intake, especially in pregnant mares, as copper has been shown to play an important role in the repair of osteochondrotic lesions.  Since mineral content of feed and forage vary throughout the world it is recommended to concentrate on a sound nutritional program since the nutritional contribution to OCD formation itself is multifactorial.

Certain sites in each joint are predisposed for OCD formation.  It is thought that a high mechanical load in areas of thickened cartilage where the blood supply is tenuous can lead to OCD due to traumatic causes.  Conformation may play a role in the distribution of the weight that the horse places on the developing bone.   It has been proposed that horses with a toe-out and upright conformation of their hindlimbs may have higher levels of hock OCDs.  This issue is intertwined with genetics as conformation is influenced by genetics.  Conformational variations can also induce more mechanical stress in particular areas and affect the ossification process via trauma.

Research investigating a possible link between genetics and OCD development is ongoing.  Studies in Standardbreds assessing the prevalence of hock OC have shown heritability rates ranging from 0.25 to 0.52.  These numbers appear significant, however certain warmblood studbooks will not allow stallions with hock OCD into their registry and after 20 years the incidence within the breed has not decreased.  This again supports the claim that OCD is a multifactoral disease.The most recent research on OCD development is at the molecular level.  The focus is on the development and maturation of cartilage, growth factors, collagen types and the expression and metabolism of these factors in bone development.

Osteochondritis dissecans can occur in many different joints but is most commonly identified in fetlocks, hocks and stifles.  Generally, the fetlocks are the first joints affected, followed by hocks, where OCD develops between 2-6 months of age.  OCD of the stifle and shoulder joints usually emerges later, often between 6-9 months of age.  In short, the larger the joint or the longer it takes to ossify, the later OCD develops.  These are the typical windows of susceptibility but since OCD may be traumatic as well as purely developmental in nature the disease may manifest itself at a later time.

Clinical Signs

In many cases, OC and OCD may be clinically silent, with no outward signs that a problem is occurring.  In other cases, there are outward manifestations of the disease.  Fetlock OCD may present as a foal or weanling with persistent distention of one or more fetlocks, with or without lameness.  Radiographs of the affected joints may confirm an OCD lesion.  However, traumatic chip fractures of P1 and sesamoid bone fractures present with similar clinical signs, so radiographs may show those lesions instead.

 
A foal or weanling with hock distention (bog) with or without lameness may also have OCD.  Hock OCD is often bilateral, even if distention is only present in one leg.  High quality radiographs are essential in this diagnosis, since small lesions may cause significant joint distention.

Stifle OCD can have a slightly different presentation, often found in a lame yearling with stifle distention.  Radiographs taken at the onset of the lameness and joint effusion may not show an OC or OCD lesion; it may require several weeks for the lesion to be evident radiographically.  However, even without radiographic evidence of a lesion at the onset of the problem, it is important to restrict exercise because the joint debris causing the effusion may result in significant damage to the articular cartilage with excessive exercise.

Diagnosis

A diagnosis of OC or OCD is most often made from radiographs.  OC lesions are characterized by a lucent area in the bone representing an area of retained cartilage.  OCD lesions often have a similar lucent area as well as the presence of a bony fragment.  However, some lesions are not able to be identified on radiographs and exploratory arthroscopy may be necessary to make the proper diagnosis.

Osteochondrosis lesions occur in specific anatomic sites in horses.  In a stifle, OCD lesions most commonly occur in the lateral trochlear ridge of the distal femur (Figure 1), the medial trochlear ridge of the distal femur and less commonly in the patella.  The most common area of OCD in the hock is the distal intermediate ridge of the tibia (Figure 2), followed by the distal lateral trochlear ridge of the talus and the medial malleolus of the distal tibia.  Fetlock OCD most commonly occurs in the proximal (Figure 3) and distal sagittal ridge of the distal cannon bones.

Since Thoroughbreds are sold at ages ranging from a few months old to adulthood, many variations of this syndrome are seen on survey radiographs.  In young horses, a lucency is often seen where the cartilage in this location has not fully ossified.  Many of these areas  will continue to ossify as the horse matures and not develop OCD.  However, some will go on to develop OCD. This is a grey area purchasers face when buying immature horses.

Treatment

Since there is not a preventive solution for OCD, horses with this disease often need to be treated.  This usually consists of either conservative medical management or arthroscopic surgery.  Conservative medical management has been shown to be successful in very young horses that still have the capacity to heal an OC or OCD lesion.  Regimes may include a modified exercise program, medication, and supportive therapy.  Exercise modification may involve reducing the intensity and amount of exercise (changing from large field to small paddock turnout, for example) or it may be as drastic as stall rest in severe clinical cases.  Medications focus on improving the health of the joint, decreasing inflammation, and augmenting the blood flow to the area of OC or OCD.  Supportive therapy can be as simple as bandaging an effused joint.

If a lesion is non-responsive to conservative management it may need surgical intervention. Surgical treatment is generally the treatment of choice in true OCD lesions that have a flap (versus the OC lesions that characterize the initial phase of this disease).  Surgery is recommended in these types of lesions even if the horse is not showing clinical signs.  It is likely that a true OCD lesion visible on radiographs will become a clinical problem in training and thus require down time for surgical treatment during the training or racing process.  Therefore, it is best removed before the joint is inflamed and further damage occurs.  Prognosis varies by joint but is generally favorable, except in the case of the shoulder joint.

In a study of Thoroughbreds with stifle OCD affecting the femoropatellar joint the affected horses’ overall racing performance was not significantly different than their unaffected siblings.  Fewer of these horses started races at two years old, but there was no difference at three years of age.  The size of a stifle lesion can be a concern when a horse is marketed; however no study has been able to link the size of the lesion with performance.  It is also important to note that the radiographic size of an OCD is not always consistent with the true size identified at surgery because a portion of the OCD is cartilaginous and therefore not identifiable radiographically. 
A study of hock OCD in Thoroughbreds and Standardbreds who underwent arthroscopic removal of the OCD lesion showed the overall racing performance was not different between affected horses and their siblings. The site of the lesion also had no impact in  performance.

There has not been a study published assessing racing performace in horses with fetlock OCD lesions.  However, studies involving multiple breeds show favorable results from surgery.  Ninety perfect of horses who had proximal sagittal ridge OCD lesions arthroscopically debrided returned to athletic activity.

Conclusion
Osteochondritis dissecans can be a confusing and concerning disease.  Although research into its causes is ongoing, there are many effective treatment options available.  Many lesions will heal without requiring surgical intervention and the prognosis for those requiring surgery is generally favorable as well.

Back problems - how they can affect performance, and how to treat them

It is well documented that horses can suffer with back problems and they tell us by their actions. Sometimes the signs are blatant – for instance the horse stops jumping, or displays an obvious aversion to being saddled. Most of the time the signs are much more subtle. The animal may slightly change its way of moving in order to avoid pain and if untreated this becomes a chronic and long term problem, the slight change of gait becoming a progressive shortening of stride and a reduced level of performance.

The power source in the equine comes from the hind limbs propelling the body forward. If there is pain within that area the animal will use less power – and therefore go slower, or be unable to clear fences – than if it felt no pain. Traditionally we look at a horse being ‘trotted up’ in a straight line as a way of assessing soundness. This is an adequate measure in many cases where there is obvious lameness in one limb however a lame horse can ‘trot up’ sound and this shouldn’t be the only measure of soundness. Other tests such as trotting on a circle in both directions, on both hard and soft surfaces should be used. Assessing the animal at a walk on a level surface and observing from both the rear and from the side is also a very useful tool in diagnosing a slight lameness or restriction of gait. What manifests itself at a walk will still be there at a gallop. And knowing how the animal moves when sound and supple is key to knowing when something is starting to go wrong – perhaps catching a small problem before it becomes a serious lameness issue. Just saving itself from a fall or slip up when in the field can be enough to cause a problem.

A momentary error of judgment by horse or rider can force a horse to use its athletic ability to get out of trouble. A twist or over-big jumping effort can be enough. The horse can go on to complete the course or win the race that day but later, when the body has cooled down and the tired muscles are trying to recover pain can develop because of that over exertion. A subluxation may have occurred An almost imperceptible lameness or a restriction of free movement of the limbs can make all the difference between winning and losing. A slight ache or low grade back pain can make all the difference between staying the distance and tailing off last. Do horses have an ‘off day’? Or is there an underlying problem which is preventing full extension, making the animal hold itself back in order to avoid pain? The Spinal Cord is the keystone of the body. Maintaining its health and integrity is imperative in maintaining the health and wellbeing of the body as a whole, and doubly so in the case of a performance athlete.

The protection of the spinal cord is paramount in the actions of the horse or any vertebrate. The nervous system controls the whole body, with nerve control of practically every cell of the body. Subluxations or trapped nerves can interfere with the ability of the nervous system to function to the best of its ability both in control and in counteracting disease. Manipulation is therefore a means of reducing these subluxations to improve the functioning of the whole body. The skeleton is responsible for supporting the body and providing it with a strong framework consisting of rigid components which can move relative to each other at articulating joints. The spinal column provides protection to the spinal cord.

If a joint in the spinal column were to be dislocated that would result in damage to the spinal cord and paralysis or death. Between each pair of vertebrae a pair of spinal nerves leave the spinal cord through a small ‘gap’ in the muscles, ligaments and other soft tissues. A subluxation is where the joint between two bones is misaligned – muscles go into spasm and can pull one of the bones of the joint slightly out of alignment. If a joint is subluxated then the two surfaces are not quite in the correct position and nerves become impinged or ‘trapped’.

A nerve which has become trapped cannot send signals to muscles therefore function is affected. The equine athlete, and particularly the race horse, is highly susceptible to damage of the back, neck and poll. The body is put under a great deal of stress and pressure during breaking and fitness work whilst still immature. Added to this the horse must learn to carry the weight of a rider on its back and to balance itself with this shifting weight. Exertion such as galloping and jumping stresses the musculoskeletal structure and it is whilst under stress and when fatigued that injuries can occur more easily. The neck, chest withers and shoulders are of paramount importance to the action of the forelimbs.

The main nerves which feed the forelimbs leave the spinal cord between vertebrae in the lower neck and chest area (C6 –T2). If a horse struggles to flex and bend its neck to each side, up and down, shows stiffness or pain reactions it will cause restricted limb action, reduced ability to gallop, reduced speed, reduced stamina and reduced performance. As a highly strung and active animal the young horse is likely to be ‘sharp’ and difficult to handle during breaking. Whilst lunging they are prone to over-excitement resulting in leaping, bucking, rearing, spinning around etc - once backed they are still likely to display these behaviours. Rearing followed by unbalancing and going over backwards, or rearing whilst tied up with the entire weight of the body being taken over the poll region by the headcollar can lead to damage of the neck, withers and back. Rearing and hitting their head on a stable beam or flinging up the head and hitting it on the door frame or in a vehicle are all possible scenarios for damage to the poll and neck resulting in tension, pain and the development of other symptoms.

Sensitive withers can be just ticklishness but could also be soreness from the front limbs and neck. Concussion can travel right up the forelimbs resulting in sore withers. Of course a horse of any age can become sensitive in the neck and poll and often we do not know what they have done or when they have done it, unless it can be attributed to a particular incident such as a crashing fall or getting cast in the stable. Often the problem exists without explanation and could have been there for months or years – like living with a permanent head ache. Treatment with manipulation is straightforward and can give lasting relief. The main nerves which feed to the hind limbs leave the spine in the lumbar and sacral region (L4 - S2) and inflammation, soreness and pain in this area can and does cause the horse to take a shorter hind stride or unequal hind strides. The result of this will be a reduction in power leading to slower galloping speed and/or reduced stamina and failing to stay the distance.

The inexplicable poor performance of any horse could be attributed to any of the above. Fitness to do the job required is a vital part of injury prevention. Weeks of slowly building up the workload are necessary to attain the level of fitness needed for the job in mind. Additionally training involves keeping the body free from aches and pains which might lower the level of performance that the individual can attain. During training nerve damage can and does occur which will cause restrictive movement and a loss of straightness. This can be due to conformational defects, concussion, over-exertion, muscle strain, or injury.

There are no absolutes when it comes to conformation of the limb and the flight of the limb through the phases of a stride. Generally we look at conformation relating to the breed or type of the animal when standing. Some abnormalities or defects may only be evident during a phase of stride and may affect a pair of limbs or a single limb. Abnormal development within a joint can also cause a limb to exhibit a lateral gait defect. Normally the joints such as fetlock, carpus and tarsus work in a hinge-like fashion, backward and forward in a straight line parallel to the horse’s midline. An abnormality can produce a swivel-like motion and cause the limb to arc in flight. Even if a horse shows all the conformational traits that theoretically add up to straightness, if it experiences pain in any part of its body it may break all of the conformation rules in order to use its limbs in a manner which creates the least stress and pain.

An injury or soreness in a limb can cause a horse to protect one portion of the limb when landing, subsequently altering the arc of the foot’s flight. When a horse has pain in a part of the body other than the hooves or limbs, its balance during movement may be negatively altered as it compensates for the soreness. Back soreness can mimic lower limb lameness and alter foot flight. A variety of factors can cause a horse to carry its body in a stiff or crooked fashion. Sometimes the stiffness or pain is subtle but just enough to prevent the horse from tracking straight. As most people will know from personal experience – back pain reduces their ability to move freely, slows them down and if left untreated is debilitating and can lead to a long term loss of full musculoskeletal function together with general irritability.

This is no less the case in the horse and it does not necessarily mean that the horse is lame only that performance has been reduced. A horse suffering with back or neck pain will be unable to gallop as fast as it did prior to the injury, will be unable to ‘stay’ as far. The pain will restrict it and it will be unwilling to keep galloping thereby being seen to fade in the last furlongs or in severe cases never being able to lay up with the pace and being adrift from the offset. By being vigilant to the signs pain and of over-exertion and by allowing for recovery of the musculoskeletal system after work these problems can be minimised. The signs can be subtle but they are there – sometimes rest is needed, sometimes an injury has occurred which will require treatment.