Exercise testing may be used to gain information about progress in a training programme, or information relating to a horse’s performance. Testing can be done on a treadmill or under field conditions. Treadmill testing is convenient with multiple tests easy to standardise; field testing has the advantage of being more easily accessible and relates more specifically to how the horse might respond in competition as the conditions are more representative of ‘real life’. Exercise tests are often carried out by vets investigating poor performance and/or respiratory noise in sport horses. Due to advances in technology, much more equipment is available for monitoring speed, stride variables, respiratory and cardiac function during exercise than was possible 15 years ago. Overground endoscopy allows vets to monitor the function of the horse’s upper airway whilst the horse carries out a piece of work on a gallop or racetrack. Many horses suffer from dynamic upper airway conditions which can only be reliably diagnosed by monitoring the function of the upper airway whilst the horse is at maximal exercise. It aids in diagnosis of conditions such as dorsal displacement of the soft palate and recurrent laryngeal neuropathy. Prior to this technology being available, dynamic upper airway conditions were investigated using a high speed treadmill and horses had to be trained to run on the treadmill before they could be tested.
Exercise testing may also be used by trainers to find out how hard their horse is working and whether or not the work they are doing is actually improving their horse’s fitness. To obtain useful information from heart rate obtained during exercise, and to compare how heart rate responses alter over time, the speed of running must be measured alongside heart rate. These days, equipment is readily available which monitors combined heart rate, speed and stride frequency. A fit horse will be capable of running at any given speed with a lower heart rate than the unfit horse. In other words, a horse’s submaximal heart rate decreases with training. Exercise testing can be used by squads preparing for international competition in eventing and endurance in order to ensure horses are sufficiently prepared for the demands of competition. An unusually high heart rate at any given speed may indicate loss of fitness or loss of performance, the latter possibly as a result of injury, illness or overtraining.
Overground Endoscopy Case Study
A 7 year old National Hunt racehorse suffering from loss of performance. The trainer reports that the horse is ‘pulling itself up’ in a race.
Diagnosis: Following the below-expectation race the horse has a resting scope performed at the yard, this reveals no significant abnormalities. About 10 days following racing, the horse undergoes an overground endoscopy. This involves fitting a bridle adapted to hold the scope in place, and the horse exercising with the scope, and a mobile light source, recording device, pump and blue tooth transmitter. The horse warms up at the trot and canter, before galloping 2400m (12 furlongs). The overground endoscopy shows that the palate becomes unstable and then displaces in the last 400m of this exercise. This causes the horse to back off its exercise. This explains why the trainer describes the horse as ‘pulling itself up’. An ECG is carried out during exercise and recovery which shows no evidence of abnormal electrical activity. When the vet listens to the horse’s heart immediately post exercise there is a mild right sided murmur (tricuspid regurgitation) but this is not considered to be contributing to the horse’s loss of performance.
Treatment: A tie-forward procedure is carried out under general anaesthetic.
Recovery: The horse returns home the day after surgery. It is fed off the ground for three weeks (to reduce tension applied to the sutures when the head is extended), it has box rest for ten days, then resumes walking and trotting exercise for ten days, and resumes cantering exercise three weeks after surgery