Investigation of the incidence and type of injuries associated with high-speed treadmill exercise testing S. H. FRANKLIN*, S. Z. BARAKZAI † , A. COUROUCÉ-MALBLANC ‡ , P. DIXON † , K. J. NANKERVIS § , J. D. PERKINS ¶ , C. A. ROBERTS**, E. VANERCK-WESTERGREN †† and K. J. ALLEN ‡‡ School of Animal and Veterinary Sciences, University of Adelaide, Roseworthy Australia SA5371; † Department of Clinical Veterinary Services, Royal (Dick) School of Veterinary Medicine, University of Edinburgh, Roslin, UK; ‡ ONIRIS, Ecole Vétérinaire de Nantes, Nantes, France; § Equine Veterinary and Therapy Centre, Hartpury College, Hartpury, Gloucestershire, UK; ¶ The Royal Veterinary College, Department of Clinical Veterinary Services, London, UK; **Department of Physiology, Development and Neuroscience, University of Cambridge, UK; †† Médecine interne et médicine sportive du cheval, Bruxelles, Belgique; and ‡‡ Department of Clinical Veterinary Science, University of Bristol, Langford, North Somerset, UK. Keywords: horse; treadmill; exercise; musculoskeletal injury Summary Reasons for performing study: During the past 20 years, treadmill exercise testing has played an important role in both the study of equine exercise physiology and the investigation of poor athletic performance. However, it has been suggested that some trainers and veterinarians may be reluctant to refer horses for treadmill exercise testing because of fears that horses may be at increased risk of musculoskeletal injury during treadmill exercise. Objective: To investigate the incidence and types of injuries sustained by horses undergoing treadmill exercise. Methods: Data were collated from 9 centres in the UK, France and Belgium, and the prevalence and types of injury were established. Results: A total of 2305 records were reviewed, with 2258 horses performing treadmill exercise. There was an overall injury rate of 5.4%. However, the majority of injuries sustained were minor in nature (4.7%). Only 13 horses (0.6%) sustained major injuries in association with treadmill exercise. These included 5 cases of severe exercise-induced myopathy, 4 fractures (of which 1 was catastrophic), 2 tendon injuries, 1 case with undiagnosed severe lameness and 1 with marked exacerbation of a previously diagnosed lameness. Two other major incidents were reported but were not directly associated with treadmill exercise (one had iliac thrombosis and one collapsed and died as a result of a pulmonary embolism). Conclusions: This study confirms that the majority of horses undergo treadmill exercise without incident. The majority of injuries that did occur were minor in nature and the incidence of major injuries was similar to that reported during competition elsewhere. Potential relevance: Treadmill exercise is a safe procedure and does not appear to pose an increased risk of injury in comparison with overground exercise. Introduction Treadmills have been used for the scientific study of equine exercise for over 100 years (Erickson 2006). Persson (1967) was the first to use the high-speed treadmill to study exercise physiology in horses and, since that time, research into exercise physiology has increased dramatically with modern treadmills enabling the study of a large range of physiological variables (Erickson 2006; Evans 2007). In addition, during the past 20 years high-speed treadmill exercise (HSTE) testing has played an important role in the investigation of poor athletic performance in equine athletes (Morris and Seeherman 1990, 1991). Clinical exercise testing is important for the investigation of disorders that may limit performance in horses because resting examinations are frequently equivocal or unrewarding (Evans 2007). In particular, high-speed treadmill exercise testing has been invaluable for enabling endoscopic examination of the upper respiratory tract (URT) during exercise. It is now well recognised that resting examinations of the URT are not representative of dynamic events occurring during exercise (Kannegieter and Dore 1995; Tan et al. 2005; Lane et al. 2006). Despite this, the majority of horses undergo treatment for upper airway obstruction on the basis of clinical history and resting endoscopy alone (Franklin 2002). It appears that there is frequently reluctance amongst owners and trainers to refer horses for treadmill investigation. There are a number of proposed reasons for this reluctance to subject horses to a high-speed treadmill exercise test. These include the need to transport horses to a specialist centre, the cost involved and concerns regarding the perceived risk of injury. This has led to a move towards field exercise testing and has recently resulted in the development of overground endoscopy (Franklin et al. 2008; Desmaizieres et al. 2009; Pollock et al. 2009). However recent questions regarding the suitability of some field testing protocols for enabling a diagnosis of conditions such as dorsal displacement of the soft palate suggest that the treadmill remains a useful tool for clinical exercise testing (VanErck-Westergren et al. 2009; Allen and Franklin 2010). *Corresponding author email: samantha.franklin@adelaide.edu.au [Paper received for publication 01.02.10; Accepted 21.06.10] © 2010 EVJ Ltd 70 EQUINE VETERINARY JOURNAL Equine vet. J. (2010) 42 (Suppl. 38) 70-75 doi: 10.1111/j.2042-3306.2010.00234.x