Researchers have defined a number of conditions affecting specific breeds—many of which developed as a result of selective breeding. | Photo: iStock

By knowing what diseases certain horses are predisposed to, owners and breeders can take steps to curb undesirable conditions

Appaloosas are prone to eye problems. Quarter Horses tend to tie up. Arabians can produce immune-deficient foals. Today it’s common knowledge that some breeds are more predisposed to certain conditions than others. But it was only a few decades ago that researchers first identified these genetic disorders in horses. Since then they have defined a number of conditions affecting specific breeds—many of which developed as a result of selective breeding, or breeding for highly desirable qualities such as performance or appearance.  

A classic example is researchers’ discovery that linked the muscle disease hyperkalemic periodic paralysis (HYPP) to the Quarter Horse sire Impressive. In 1996 the American Quarter Horse Association established mandatory testing for all Impressive’s descendants to prevent perpetuating the condition. Now any foal that tests homozygous for HYPP cannot be registered with the organization.

But many owners across a variety of breeds know nothing about their horses’ lineage. This means breeding continues to result in foals with genetic conditions. Knowing which horses could potentially have genetic conditions is important not only for buyers and breeders but also the overall health of the breeds themselves