New Hereditary Condition Identified in Quarter Horse Foals

In the spring of 2020, a Quarter Horse foal in Oregon began showing signs of weakness and incoordination shortly after birth, prompting veterinary investigations. Tests for common neurologic diseases yielded no results, leading researchers at the University of California, Davis, to discover a new hereditary condition known as Equine Juvenile Spinocerebellar Ataxia (EJSCA).

Initially focused on the Oregon foal, the research expanded as similar cases were reported from Texas, confirming related cases among affected foals. Briana Brown, a graduate student working with Dr. Carrie Finno, detailed the progression of the disease, stating that the foals appear healthy at birth, but signs of ataxia, or incoordination, manifest within one to five weeks. The deterioration of protective myelin sheaths around neurons leads to impaired nerve function, causing the foals to struggle with mobility. Currently, no treatment exists for EJSCA, and foals often must be euthanized as the condition progresses. Genetic testing revealed that all affected foals shared a lineage from a single stallion, indicating that EJSCA is likely an autosomal recessive disease. This means that two copies of the detrimental gene must be inherited for symptoms to appear. Breeders are encouraged to test their horses for the gene mutation to prevent the propagation of this severe condition.

The test is accessible through the UC Davis Veterinary Genetics Laboratory.