Editor’s Note: This article is part of TheHorse.com’s ongoing coverage of topics presented at the British Equine Veterinary Association’s 51st annual Congress, held Sept. 12-15 in Birmingham, U.K.

Incomplete, or hairline, fractures of the cannon bone can occur in horses due to acute trauma as well as repetitive loading (known as stress-related bone injury).

Although most of the research on these injuries has involved racehorses, sport horses and general-purpose riding horses are not exempt. Thus, Rhiannon Morgan, BVSc, MRCVS, who is currently completing her PhD at the University of Liverpool’s Institute of Aging and Chronic Disease, conducted a study comparing sport horse cannon bone fractures to those of racehorses. She presented her findings at the British Equine Veterinary Association’s 51st annual Congress, held Sept. 12-15 in Birmingham, UK.

In her retrospective study, Morgan evaluated the medical records of horses examined by Sue Dyson, MA, VetMB, PhD, DEO, FRCVS, head of Clinical Orthopaedics at the Animal Health Trust, in Newmarket, England, from 1985 to 2010. She included in the study horses with pain localized to proximopalmar (upper back) region of the cannon bone and radiographic (X ray) evidence of an incomplete fracture or changes indicating potential fracture. From these she identified 55 horses–15 racehorses aged 2 to 10 years and 40 sport horses aged 3 to 14 years. The sport horses included 13 Thoroughbreds, eight Warmbloods, four Thoroughbred crosses, and 15 other breeds