The prestigious Scientific American journal is not where a person with an interest in horse racing would ordinarily look for information on the sport/industry.  However, in late February 2020, a provocative article was excerpted on the Scientific American website titled “Thoroughbred Horses are Increasingly Inbred.”

The excerpt reported on findings from a study of approximately 10,000 Thoroughbred horses “from all the major breeding regions of the world” that analyzed “genetic diversity at thousands of genetic markers across the entire genome…”  The study is purported to be the “largest set ever examined.”  The lead researcher is Emmeline Hill, a professor at University College Dublin and the chief scientist at the equine science company Plusvital.

Two principal findings are:

First, “…there has been a highly significant increase in inbreeding in the population over the last 45 years and probably the greatest increase is seen in the last 10 or 15 years”

Second, “…97 percent of the horses [in the study] traced back to a single stallion, Northern Dancer…And his descendants have been the dominant sire lines in Australia and Europe in the last 25 years.”

Professor Hill said:  “…without genetic diversity, you get health and behavior issues related to inbreeding.”

At a time when the racing enterprise, particularly in North America, is desperately searching for ways to greatly diminish racing and training horse fatalities, Professor Hill’s in-depth research is especially informative and at the same time troubling.  It is troubling in the sense that how to mitigate inbreeding in modern Thoroughbred horses is a conundrum.  Breed registrars in the various countries cannot force breeders to take steps that would at least alleviate the inbreeding situation.  Moreover, capping the number of foals by a given stallion that can be registered in a year may be a step in the right direction, but its practicality is problematic.

(Click here to go to the Scientific American excerpt)

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