Equine Veterinary Journal ISSN 0425-1644 DOI: 10.1111/evj.12285

Analysis of stress fractures associated with lameness in Thoroughbred flat racehorses training on different track surfaces undergoing nuclear scintigraphic examination M. C. MACKINNON*, D. BONDER†, R. C. BOSTON‡ and M. W. ROSS‡ Milton Equine Hospital, Campbellville, Ontario, Canada † Toronto Equine Hospital, Mississauga, Ontario, Canada ‡ Department of Clinical Studies, New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania, USA. *Correspondence email: [email protected]; Received: 29.11.12; Accepted: 06.04.14

Summary Reasons for performing study: There is limited information regarding the impact of training track surface on the occurrence of stress fractures. Objectives: To evaluate the impact of training track surface on the proportion of long bone and pelvic stress fractures associated with lameness in Thoroughbred horses in flat race training undergoing nuclear scintigraphic examination. Study design: Retrospective study. Methods: Scintigraphic examinations of Thoroughbred flat racehorses were evaluated from 2 hospitals (hospital A [Toronto Equine Hospital], 2003–2009, and hospital B [George D. Widener Hospital for Large Animals, School of Veterinary Medicine, University of Pennsylvania], 1994–2006). Horses admitted to hospital A trained at a single track, at which the main training surface changed from dirt to synthetic on 27 August 2006. Two distinct populations existed at hospital B: horses that trained on dirt (numerous trainers) and those that trained on turf (single trainer). All scintigraphic images were evaluated by a blinded reviewer. Fisher’s exact test and logistic regression were used when appropriate, and significance was set at P70% of total training time for each horse. A second subgroup of horses admitted to hospital B were trained by numerous trainers on dirt surfaces at several local racetracks (dirt was the only training surface available at the racetracks). Horses were excluded if the predominant training surface was unknown. Hospital A was located within 2 km of the racetrack, whereas hospital B attracted referrals of horses training and racing in the Mid-Atlantic area. Scintigraphic images and medical records from horses that met the inclusion criteria were examined and data recorded (signalment, trainer, predominant training surface, history and nuclear scintigraphic findings). Images of all scintigraphic examinations were evaluated by a blinded reviewer (M.W.R.) for a description of the presence and location of the stress fracture(s). Stress fractures were defined as a focal area of increased radiopharmaceutical uptake in the cortex of a long bone or a pelvic bone. They were confirmed to be present and definitively cortical in location using orthogonal or oblique images. The location of each stress fracture was described by bone (scapula, humerus, radius, tibia, ilium or ischium) and position within the bone (metaphyseal or diaphyseal, proximal, mid or distal, medial or lateral and cranial or caudal). Horses with stress fractures of the McIII and the third metatarsal bone were excluded. Repeated nuclear scintigraphic examinations or scintigraphic examinations

Analysis of stress fractures associated with lameness in Thoroughbred flat racehorses training on different track surfaces undergoing nuclear scintigraphic examination.

There is limited information regarding the impact of training track surface on the occurrence of stress fractures...
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