Researchers at the University of California-Davis recently published research on Equine Juvenile Spinocerebellar Ataxia (EJSCA), a recessive genetic disease found in Quarter Horses. Foals with two copies of the gene experience ataxia, or loss of coordination, and the disease is always fatal. Breeding carriers has a 25% chance of producing a foal with no EJSCA, a 50% chance of a foal with one copy of the gene, and a 25% chance of a homozygous EJSCA foal.
Foals inheriting two copies of EJSCA start to show mild incoordination in their hind limbs around 10 days after birth, with rapid progression leading to the foal being unable to stand and requiring euthanization. Dr. Finno’s research supports the hypothesis that EJSCA is an autosomal recessive disease, but the prevalence in the Quarter Horse breed is still being investigated.
Owners, breeders, and veterinarians should watch for signs of EJSCA in foals, as affected foals show impaired coordination in the hind limbs, followed by the forelimbs, and difficulty turning without stumbling. Testing for EJSCA is available at the UC Davis Veterinary Genetics Lab, and it is recommended that breeders follow best practices and have their stock tested to prevent the birth of foals with EJSCA.
