In the case of dogs, everyone knows mutts make the best pets in terms of health and attitude, but it’s the purebreds that sell. What about horses' Are we doing the same thing to equine breeds that happened to canine breeds' Are we breeding for an ideal that cannot be achieved and in the process accentuating genetic problems' Probably.
Conformation faults, temperament, even a tendency toward navicular are all problems that can be correctly blamed on previous generations. When we breed horses, we hope the good will prevail and the flaws will remain unseen. But the super-foal is rare.
Of course, most serious genetic faults are not deliberately selected for in breeding. What happens is that in our well-intentioned efforts to select for desirable characteristics, we also sometimes magnify flaws. Sooner or later, that flaw can no longer be ignored.
A classic example is the Arabian. This is the oldest recognized pure breed and arguably the most elegant, breathtaking and beautiful creature on earth. The first case of the horrible genetic defect Severe Combined Immunodeficiency Disorder (SCID) was reported in 1975. The defect is caused by an autosomal recessive gene, which means a mating of two carriers has a 25% chance of producing an affected foal. This defect is so widespread that we now even have tests available to detect the gene.
Natural selection would have eliminated SCID long before domestication, or we would have seen its effects prior to 1975. Specific lines have not yet been identified, but there is general agreement that it is found in horses that represent the Arabian breed ideal: large eyes, prominent dish, incredible ears, even that intangible presence these horses sometimes have. We bred the ultimate Arabian, except for that genetic flaw.
There are many other examples — HYPP and tiny feet prone to navicular disease in Quarter Horses; moonblindness and skin cancer in Appaloosas; and long necks in Thoroughbreds and roaring.
Other problems will surface as we continue to assign inflated value to horses with “papers” but no record of breed inspection or performance. While pure breeds must be preserved — this is not a call to stop breeding purebreds — breeders and breed organizations must be more diligent in identifying problems that could be hereditary and work toward eliminating then. We could also expand the gene pool by supporting halfbred registries, which could create a moderately priced market and encourage outbreedings yet retain a degree of status.
It also may help increase the quality of purebred horses if more registries followed the warmblood standards for registration as breeding animals, including testing and monitoring offspring, before granting full breeding status. While there are no easy answers, it is time to address the issue.
’Til Next Month,
-Eleanor M. Kellon, VMD