Genetic cause identified for fatal equine disease

Researchers have identified a genetic cause for a fatal condition in thoroughbreds, opening the door for diagnostic testing that could help prevent cases in newborn foals.

The University of California researchers say this is the first genetic variant identified for the condition, equine familial isolated hypoparathyroidism, which can lead to devastating losses for owners and breeders. Genetic testing can now be performed at the UC Davis Veterinary Genetics Laboratory to identify horses with the variant and avoid mating carriers that could produce affected foals.

EFIH causes low blood calcium concentrations, resulting in involuntary muscle contractions and muscle stiffness. That can lead to a stiff gait that progresses to an inability to stand, seizures, fevers and an abnormally fast pulse. Parathyroid hormone is typically produced to increase calcium levels in the body, but in these foals, concentrations of the hormone are too low. Affected foals die or are euthanized due to poor prognosis.

“For thoroughbred owners and breeders, the loss of a foal has tremendous economic and emotional impacts,” said study coauthor Victor Rivas. “It is important to promote safe and strategic breeding habits by actively breeding horses genetically screened not only for EFIH, but for other diseases that may impact quality of life.”

More information on the study, published in PLoS Genetics, is available from UC Davis.