Media release

From: The Royal Society

Inbreeding depression and the probability of racing in the Thoroughbred horse

New research has found that in Thoroughbred racehorses, higher levels of inbreeding, measured across the whole genome, result in a lower chance of a horse ever racing. The research also identified a genetic marker with a major negative effect on racing. One percent of Thoroughbreds have two copies of the marker, and these animals have a three times lower probability of ever racing. Breeding decisions can be managed if the genetic marker carrier status of a mare and stallion are known, which will have a positive impact on animal welfare. Breed-wide programmes of genetic testing could also reduce inbreeding.