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The Official Veterinary Examination The following information is provided to help customers better understand the procedures by which the Hong Kong Jockey Club attempts to manage the suitability of horses to race. A brief description of the veterinary problems that commonly result in horses being issued with official veterinary examinations is also provided. The descriptions and explanations are necessarily brief however interested readers are suggested to follow the links provided to obtain more detailed information.
An OVE is issued by the Chief Stipendiary Steward or an Official Regulatory Veterinary Officer whenever;
OVEs are issued to, as far as possible, ensure that;
Relatively minor injuries and illnesses may require a 'no gallop' OVE which requires that the horse only undergo a clinical examination by an officer of the veterinary regulation department prior to entering to race again. COMMON VETERINARY CONDITIONS THAT MAY BE MENTIONED IN RACING INCIDENT REPORTS LAMENESS There are a number of terms used to describe lameness. These usually reflect the severity and nature of the lameness.
The following abbreviations will be used to designate the affected leg in OVE reports.
Lame Occasionally a horse will be reported as simply lame. This most often occurs when a horse has been examined after a race and has been found to be lame. There may not be sufficient time or equipment available to establish an exact diagnosis. These horses will be referred the stable veterinary surgeon for a comprehensive lameness examination and, if a diagnosis is made, the OVE report will be updated to provide more information. Tendon Injuries (Tendonitis) Tendons are strong cable like structures that transmit the pull created by a contracting muscle to bones to produce movement. They are composed of collagen and elastin fibres and are very strong but have only limited elasticity or stretch. Tendons in the horses' legs are subject to tremendous forces. They have a relatively poor blood supply and when injured heal very slowly by the formation of scar tissue. The scar tissue has virtually no elasticity. This means that an injured tendon is very prone to re-injury under the stresses of full training and racing. The tendon most commonly injured in racehorse is the superficial digital flexor tendon of the forelimb. This tendon runs down the back of the cannon and transmits the pull of the muscle behind the forearm to the bones of the foot. Getting a horse back to racing after a tendon injury requires a great deal of skill and hard work. Often a serious tendon injury will result in the retirement of the horse from racing. Suspensory Ligament Injuries (Suspensory Desmitis) Ligaments are strong bands of tissue that bind bones together and stabilize joints. The suspensory ligament runs from the top of the back of the cannon bone over the back of the fetlock joint via the sesamoid bones to attach at the back of the pastern bones. It is a very strong, fairly elastic structure that plays an important role in supporting the fetlock joint as it sinks to the ground because of the horse's weight passing over the forelimb during the galloping action. It is subject to tremendous forces during galloping especially when the muscles fatigue. When injured it also heals by scar tissue and once damaged is very prone to re-injury. Depending on the severity of the injury suspensory ligament injuries may have severe consequences for the horses' future racing career. 70% of all racetrack breakdown injuries are the result of failure of the suspensory apparatus (the suspensory ligament and the sesamoid bones) Joint Conditions Joints are the structures that allow movement where bones meet bones. For our purposes the most important type of joints are synovial joints. These joints have a joint capsule that surrounds the space between the bones that is lined by the synovial membrane that produces a lubricant, shock absorbing synovial fluid. The ends of the bone within the joint are covered by very smooth cartilage. The smooth cartilage joint surface and the lubricant joint fluid permit virtually frictionless movement of the bones over each other. Racehorses' joints are subject to tremendous stress and 'wear and tear". These stresses may result in inflammation of the joint capsule, degradation of the lubricating synovial fluid, cartilage damage, possibly chip fractures and, without careful management may progress to incurable osteoathritis. Mild joint stresses may be described as 'jarring up'. Degenerative joint disease and osteoarthritis are terms used to describe more advanced joint diseases. The horses fetlocks, knees (carpitis) and hocks (tarsitis) are most commonly affected by osteoarthitis although any joint may become arthritic. The development of osteoarthritis is one of the most common reasons that horses must be retired from racing. Back Pain As in humans, back pain is common cause of chronic pain and loss of athletic performance in horses. The causes of back pain range from simple overuse muscle soreness to ligamentous strain to osteoarthritis to spinal nerve root impingement. Back pain often results in a stiff, restricted hindlimb action. "Hot Spots" and Nuclear Scintigraphy Horses may suffer stress fractures of bones in the same way the human athletes are affected. Unfortunately horses cannot tell us where they are sore and, because of the size of horses, it is often difficult to get diagnostic X rays of areas surrounded by large masses of muscle, for example the pelvis. Also active, remodelling bone tissue may be very painful but not show signs visible on X ray until the changes are well advanced. Nuclear scintigraphy involves the injection of a radioactive substance (a radio-pharmaceutical) into the horse that travels via the bloodstream to localize in areas of increased bone tissue activity, for example where the body is attempting to repair a stress fracture or where it is attempting to adapt and model to new stresses. A Gamma camera measures the uptake of the radioactive pharamaceutical and a computer produces an image of the horses' skeleton identifying the area of increased bone activity. These areas of reactive bone are referred to as 'area of increased of radio-pharmaceutical uptake (RPU) or as "Hot Spots". Hot spots are often indicative of hairline stress fractures that may require three to four months rest from training to allow healing to occur. More information about scintigraphy may be found at http://vmthpub.vetmed.wisc.edu/la_services/surg/lameness.htm
RESPIRATORY DISORDERS Respiratory disorders are a common cause of poor racing performance and affect performance by reducing the horses' oxygen intake. Mucopus A relatively common post race finding in a horse that it is sent for post race clinical examination after returning a disappointing racing performance is " a significant quantity of mucopus was detected in the horses' trachea" Mucopus is a mixture of mucous and pus that appears during infection of the upper airways. A common name for mucopus is yellow phlegm. The presence of mucopus indicate that the horse is suffering from a respiratory infection and is unable to perform up to expectation because it is unwell and the presence of mucopus in the airways interferes with its breathing. Detection of mucopus post race after a disappointing performance often raises the question "Why was the problem not detected earlier and why was the horse permitted to race?" The answer is that although the infection may quite significant in terms of athletic performance, the outward signs are often very mild and may not be detectable without an endoscopic examination of the airways and/or a blood test close to the time of racing.
Bleeding results from the rupture of capillaries in the lung tissue that permits the escape of blood into the air sacs (alveoli) where the exchange of gases takes place within the lungs. The blood vessel and alveolar walls rupture because the blood pressure within the blood vessels becomes too high for the strength of the blood vessel walls. There is still some debate about how this actually happens but the horses' lungs are designed for very high performance exchange of gases to support very strenuous exercise. In the same way that a Formula One racing car design pushes the limits of safety and durability to achieve optimum performance, the horses cardiopulmonary system sacrifices some durability and strength for performance. Most horses bleed from the lungs to some extent after strenuous exercise. Post race surveys have shown from 40% to 90% of horses showed some blood in their airways after racing. Under the Hong Kong Jockey Club Rules of Racing, if the bleeding is so severe that blood appears at the nostrils, the horse is declared to be an official bleeder and will be banned from racing for three months. If it bleeds from the nostrils again it will be compulsorily retired from racing. However horses may bleed into their airways and not show blood at the nostrils. This bleeding may only be detected by endoscopic examination of the airways and may, or may, not affect racing performance. If blood is detected in the airways during the post race examination of horse sent for clinical examination because of a disappointing racing performance, the examining veterinary officer will make a subjective decision on whether the severity of the bleeding into the airways would have contributed to the poor performance. If the bleeding is thought to have affected the horses' performance, it will be reported as 'a significant quantity of blood was detected in the trachea of the horse on post race scoping' and OVE requirement will be issued. Horses that have bled in the past are more likely to bleed again in the future and there is no way to prevent or guarantee that a horse will not bleed again and return a disappointing performance. "Roarers" (Laryngeal Hemiplegia) Roarers are horses affected by laryngeal hemiplegia. The name comes form the 'roaring' sound that these horses make when breathing heavily during galloping. Laryngeal hemiplegia is a condition in which a muscle responsible for abducting (opening up) a flap of cartilage that closes to guard the entrance to the airway during swallowing but opens during breathing to allow the free flow of air into the lungs, becomes progressively paralysed because of nerve degeneration. The paralysed muscle is unable to lift the flap of cartilage up and out of the entrance to the airway during inspiration and it is left 'flapping in the wind' as the horse breathes in. This flapping causes vibration, turbulent airflow and the 'roaring' sound. The presence of the flap of cartilage in the entrance to the airway significantly reduces the intake of air to the lungs and compromises athletic performance. The course of the degeneration of the nerve that supplies the muscle involved is very unpredictable. The condition may be mild and progress very slowly. In these cases the horse may perform acceptably, especially over shorter distances and if they can be saved for one period of acceleration during the running of the race, because its intake of air is only mildly compromised. Other cases may progress very rapidly and an apparently normal horse may return after a disappointing racing performance and show signs of advanced laryngeal paralysis. Surgical treatment of the condition is possible by a procedure called a Laryngoplasty or "Tie Back" operation in which a permanent suture is positioned to perform the function of the wasted muscle. The procedure is often quite successful in restoring the horses' airway and horse returning to racing after surgery often show significantly improved racing performance. However some horses do not improve because they have learned to associate racing with partial suffocation caused by the laryngeal paralysis and are reluctant to race at maximum intensity. Soft Palate Conditions The soft palate is a flap of soft tissue that extends backwards into the horses throat from the hard palate. Horses can only breath through the nose and normally the soft palate forms an airtight seal that closes the mouth from the airway and allows a smooth flow of air into the lungs during breathing. In some horses this seal may be ineffective and the soft palate may displace upwards from its normal position (Dorsal Displacement of the Soft Palate) and interfere with breathing. Riders often report that the horse slowed suddenly in running and made a gurgling noise or that the horse 'choked down' in running. The problem may be frustrating to diagnose because the horse can re-position the soft palate by swallowing and often by the time the horse has returned after racing everything appears to be quite normal. The problem may be managed by the use of a tongue-tie and a cross over noseband. In cases that do not respond to conservative treatment surgical correction may be attempted. Epiglottic Entrapment The epiglottis is a triangular flap of cartilage that functions as part of the seal of the entrance to the larynx during swallowing. In some horses a fold of membrane on the floor of the throat may entrap the epiglottis. When the horse breathes out forcibly during strenuous exercise the membrane balloons up like a sail and obstructs the outflow of air from the lungs. Surgical treatment of the condition is usually successful. More information about epiglottic entrapment in horses may be found at http://www.usyd.edu.au/su/rirdc/articles/cardio/epiglot.htm Heart Irregularities A dysfunction of the heart will reduce the volume of blood pumped around the body and reduce oxygen supply to exercising muscles. The common heart irregularities seen in racehorses are Arrhythmias, which literal means no rhythm to the heart beat. The most common type of arrthymia that causes poor performance in racehorses is Atrial Fibrillation. Often the only sign of the condition is a poor racing performance. All horses that undergo a veterinary clinical examination after racing are checked for heart irregularities by ausculation and, if necessary, an Electrocardiograph (ECG) examination. Horses undergoing an OVE for a heart irregularity have to show a normal ECG after the OVE gallop test. More information about atrial fibrillation in horses may be found at http://equinehospital.net/cardiology.htm Subclinical Infections Racehorses are subject to quite intense physical stress during training and racing. Stress can cause immuno-supression and cause horses to be more susceptible to infections. Often the signs of infection are mild and difficult to detect. Sight dullness, a minor increase in temperature and a loss of appetite are the only warning signs. Blood tests may be useful to detect early infections. Although the signs are mild and affected horses do not appear to be sick, the presence of an infection can have a significant effect on racing performance when horses have to be in excellent health to perform competitively. Horses found to have subclinical infections will be treated by the stable veterinary surgeon and rested. A blood test to ensure that the horse has recovered will be required as part of the OVE .
SURGICAL PROCEDURES Horse will usually be issued with an OVE requirement after having had a surgical procedure performed on them. The common surgeries performed at the HKJC include; Arthroscopic Joint Surgery Arthroscopic surgery is commonly used to remove chip fractures or damaged areas of cartilage from injured joints especially knees and fetlock joints. Throat Surgery The common throat condition requiring surgical correction include laryngeal hemiplegia, Dorsal Displacement of the Soft Palate and Epiglottic Entrapment. Colic Surgery Colic is a common name for abdominal pain. Colic surgery in the horse often involves correcting intestinal twists and obstructions.
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