Description of the incidence, clinical presentation and outcome of proximal limb and pelvic fractures in Hong Kong racehorses during 2003-2014.

BACKGROUND: Few studies have described incidences of proximal limb and pelvic fracture (PLPF) in Thoroughbred racehorses occurring on race day and during training. Information regarding clinical presentations and future racing careers in cases of PLPF is limited.

OBJECTIVES: To describe the incidence, clinical presentation and outcome of PLPF sustained by horses in racing and training at the Hong Kong Jockey Club (HKJC) between 2003 and 2014.

STUDY DESIGN: Retrospective cohort study.

METHODS: Horses with PLPF confirmed by nuclear scintigraphy, ultrasonography, radiography or post-mortem examination were identified using veterinary clinical records. Training and racing data for case horses were described. Incidences of fractures were estimated per 1000 horses in training and per 1000 race starts for fractures sustained during racing. Descriptive statistics were used to describe the study population.

RESULTS: A total of 129 instances of PLPF were sustained by 108 racehorses. The most commonly fractured bone was the humerus (49.6%), followed by the tibia (29.4%). Nine horses sustained fatal fractures, eight of which occurred during racing. The incidence of fracture during racing was 0.30 per 1000 starts. Two-thirds of fractures occurred during training. The majority of horses presented with grade 3 lameness (n = 42 of 119 injury events, 35.3%). All horses presenting with grade 5 lameness sustained fatal injuries. Following noncatastrophic injury, all horses underwent box rest and 81 horses subsequently resumed racing; 45 of these won a race. Horses were retired at a median of 25 months (interquartile range: 15-36 months) after injury.

MAIN LIMITATIONS: Protocols for resting non-training racehorses at the HKJC and for recording rehabilitation regimens post-injury prevented the calculation of horse days at risk.

CONCLUSIONS: The incidence of PLPF at the HKJC is low. Non-fatal PLPF is not necessarily a career-ending injury and many horses resume racing successfully following conservative treatment.