Prof Emmeline Hill, a specialist in equine genetics, in the lab of her company Equinome in Dun Laoghaire. Photograph: Dara Mac DónaillDarley first encountered the horse – originally named Ras el Fedowi, or The Headstrong One – in 1704 or so, in Aleppo,, and his writings from the time describe the bay colt as “immediately striking owing to his handsome appearance and exceedingly elegant carriage”.
Thoroughbred horses are what’s known in scientific circles as a closed population: they do not breed in the wild, but have their mating decisions made for them by professional breeders, who present their mares only to the best and fastest stallions. As each generation of horses has passed, breeders have focused on an ever-narrower genetic pool, creating what Hill’s company, Equinome, describes as “one of the biggest economic and welfare issues facing thoroughbred breeders”.
“Of course people are going to use the most popular sires, because they’re going to pass on the best genes,” Hill said. “You’re trying to concentrate the good genes that are in the population, but in doing so you also risk exposing the harmful genes, and that’s where the problem arises.Hill pointed out that “as you increase inbreeding, where you’re trying to double up on the good genes from ancestors, you have the potential to double up on harmful genetic mutations”.
Other studies have shown that “horses which had higher inbreeding had a lower chance of ever having a racecourse start and, of those horses that did start a race, they had a lower number of race starts over their career lifetime,” Hill said. The stud book is just a record of breeding, however, not an indication of genetic health. “A horse can be more or less inbred than it appears on pedigree,” Hill said, since no simple chart of a family tree can really show how two animals’ genes might interact.
From that database, Hill and her team have been able to create a piece of software called CheckMate, through which breeders can compare the genetics of their mare with the genetic information of a possible stallion and determine whether there is sufficient differentiation between the two. Eventually the Jockey Club dropped the proposal, but the problem of inbreeding has continued to grow.