Elisabeth Morris

The Use of Sports Medicine Techniques in Evaluating the Problem Equine Athlete

Discovering the cause of poor performance in racehorses can often represent a considerable challenge eluding the more common diagnostic techniques available at the racetrack. Application of sports medicine techniques to these problem cases can aid in the diagnosis of poor performance. Central to the development of this capability has been the use of highspeed treadmills, allowing the racehorse to be evaluated in the controlled laboratory setting, at exercise intensities equivalent to those of racing. Video and cinematographic gait analysis can be used in the diagnosis of subtle lameness conditions. Evaluating hoof balance at high speed has also become an important technique for both lameness diagnosis and prevention. Correcting hoof imbalance normalizes the applied stresses on joints, ligaments, and tendons. Abnormal upper airway function resulting in increased resistance to airflow is major cause of poor racing performance. Often this cause of upper airway dysfunction is difficult to evaluate at rest or after exercise. A definitive diagnosis can be made in these cases using treadmill endoscopy to visualize upper airway function during peak exercise. Lower airway function can also affect performance capability. Radiographic and scintigraphic imaging modalities can be used to evaluate both global and regional lung function in cases of suspected pneumonia, EIPH, COPD, or emphysema. Reduced metabolic fitness can be a primary cause of poor performance due to inherent differences in capability, pathologic changes in the major body systems involved in exercise, or inadequate training. Metabolic stress testing can be used to evaluate the level of fitness in these cases. Orthopedic imaging has also become a valuable diagnostic technique for evaluating musculoskeletal injuries. Scintigraphic evaluation of soft tissue and bone and CT scanning are used to localize the source of lameness and to grade the severity of various orthopedic conditions such as arthritis and stress-induced bone disease that are often difficult to categorize with conventional radiography.

Application of clinical exercise testing for identification of respiratory fitness and disease in the equine athlete.

Maximal exercise testing is a valuable diagnostic tool for the evaluation of exercise intolerance and level of fitness in the equine athlete. A description of the standardized incremental exercise testing protocol and interpretation of the results of the test is followed by a discussion of more specific diagnostic techniques aimed at identifying pulmonary dysfunction as a cause of suboptimal performance.

Dynamic Evaluation of the Equine Upper Respiratory Tract

Each case of suboptimal equine athletic performance should be evaluated in a comprehensive manner, including physical examination; clinical pathologic analysis; and evaluation of the neurologic system, the musculoskeletal system, and the upper and lower respiratory system. A vital part of this examination is the clinical evaluation of dynamic upper respiratory tract function of the horse during treadmill exercise, which allows the observation of upper respiratory tract function during conditions simulating competitive racing. It generally is agreed that the endoscopic identification of an upper respiratory tract abnormality in the resting horse does not necessarily indicate a clinical problem. It is equally certain that the absence of an upper respiratory abnormality at rest does not rule out the presence of an intermittent obstruction during strenuous exercise. Although many upper respiratory abnormalities may be diagnosed at rest (specifically, most cases of continual epiglottic entrapment and total laryngeal paralysis) the diagnosis of intermittent DDSP, intermittent EE, and some cases of idiopathic laryngeal neuropathy necessitates the observation of the upper respiratory tract during strenuous exercise. This diagnostic technique allows absolute documentation of whether upper airway dysfunction is a contributing factor to inadequate athletic performance in each individual horse. In the decade to come, it is clear that the evaluation of potential upper respiratory tract dysfunction as a cause of exercise intolerance should be performed before specific recommendations are made for treatment in each equine athlete. In many cases, this evaluation has circumvented the unnecessary attempt at correction of suspected but nonexistent respiratory dysfunction. Thus, these horses benefit from a continuation of a comprehensive performance evaluation, enabling an elucidation of the true cause of inadequate performance. The routine use of this diagnostic technique at Tufts University School of Veterinary Medicines Equine Sports Medicine Center has greatly expanded the documentation of the diversity of upper respiratory dysfunctions that can occur. It also has enabled a precise description of the anatomic abnormalities resulting in each case of upper airway obstruction. In addition, this new knowledge has made us cautious regarding conventional treatment regimens and allowed the capability to individualize attempts at surgical and managemental correction of each dysfunction to optimize the success of the treatment for each horse.