Fracture risk in thoroughbred horses is a complex condition with an underlying genetic basis, British researchers have found.

Thoroughbred racehorses are subject to non-traumatic lower limb bone fractures that occur during racing and exercise.

The researchers, whose findings have been published in the journal, BMC Genomics, set out to establish whether susceptibility to fracture may be due to underlying disturbances in bone metabolism which have a genetic cause.

Fracture risk has been shown to be heritable in several species, but their study was the first genetic analysis of fracture risk in the horse.

Samples for genetic testing were taken from 269 thoroughbreds that sustained catastrophic lower limb fractures while racing on British racecourses, resulting in euthanasia.

For a control group, the researchers used 253 horses over four years of age that were racing during the same time period as the cases, and had no history of fracture at the time of the study.

The horses sampled were bred for both flat and National Hunt jump racing.