At StallionCompare.com, we strive to keep our community informed about the latest developments in equine health. Recently, researchers at UC Davis have identified a new inherited neurological disease affecting American Quarter Horses: Equine Juvenile Spinocerebellar Ataxia (EJSCA).
Earlier this week, a breeder and stallion owner publicly shared that their stallion tested positive for EJSCA. Their transparency and swift action to inform the community is a true testament to the quality breeders and owners in our industry dedicated to supporting the success and wellbeing of future generations. It’s encouraging to see many other stallion owners promptly testing their horses as well. At StallionCompare.com, we also tested our horses with UC Davis to confirm carrier status.
Similar to HERDA and GBED, EJSCA remains asymptomatic in carrier horses. Problems arise only when two carriers breed, producing a homozygous foal affected by the disease. Though we are in the early stages of understanding EJSCA, we plan to keep our readers updated with any future information and findings. We have already updated our platform to support these tests. We invite all stallion owners to submit their test results, and we will continue to monitor social media for updates.
We would be remiss not to mention that while these diseases might seem “new” to us, they are not necessarily new in the broader context. Diseases like EJSCA, much like the discovery of HYPP, HERDA, GBED, MYHM/IMM, and others, have roots in bloodlines that go back decades. Only now, with advanced genetic testing, are we able to identify these issues and work towards preventing them in future generations. The key takeaway here is to test your horses, breed with thorough preparation, and avoid crossing two carriers to minimize the risk of producing homozygous foals. This principle applies to any genetic defect, including OLWS and some of the white/pattern genes. By being vigilant and proactive, we can ensure the health and success of future generations.
We have several stallions on our platform who released test results just this week alone, including:
Phenotype and Genetic Inheritance
EJSCA is an inherited disease causing ataxia, or incoordination, in foals. Affected foals typically develop symptoms between 1 and 4 weeks of age, with the disorder progressing rapidly until they are unable to stand without assistance. Dr. Carrie Finno and her team at UC Davis found that hind limbs are more severely impacted than the front, leading to a distinctive sideways walking motion as the foals turn their hind limbs while keeping their front limbs planted. Unfortunately, as the disease progresses, the foals become unable to stand without assistance and must be euthanized.
The disease is inherited as an autosomal recessive trait. Here’s what that means for breeders:
| Status | Definiton |
|---|---|
| N/N | Normal, non-carrier. Horses will not have EJSCA and will not transmit the JSA allele to their offspring. |
| N/JSA | Carrier. Horses will not have EJSCA but are carriers (heterozygous). They may transmit the JSA allele to 50% of their offspring. Breeding two carriers results in a 25% chance of producing an EJSCA-affected foal, (homozygous). |
| JSA/JSA | Affected. Foals will likely develop the disease. (Homozygous). |
Genetic Testing
Genetic testing is now available to identify carrier horses, which is crucial for breeders to prevent passing this devastating condition onto future generations. Breeding two carrier animals has a 25% chance of producing an affected foal. This testing is particularly relevant for the American Quarter Horse breed.
For more details on EJSCA and genetic testing options, visit the UC Davis Veterinary Genetics Laboratory and their EJSCA test page.
Have some questions? Reach out to us on our website, via email, or right on Facebook.
References
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UC Davis. 2024. Accessed July 2024. vgl.ucdavis.edu
Natashya V.
Founder, StallionCompare.com | Creative Director
Natashya, the founder of StallionCompare.com, is a dynamic force in both the equine and creative industries. As a lifelong equestrian, Natashya’s journey with horses began with Quarter Horses in her hometown in British Columbia, Canada. During her college years she took a brief (and eye opening) hiatus from Quarter Horses to work in the Thoroughbred industry – returning to the AQHA circuit as a young adult. Natashya was also able to reconnect with the quarter horse industry through design. She worked with former owners of Pleasurehorse.com and Show Horse Today on their design needs prior to Robyn Duplisea purchasing the business. Natashya also worked at Horse Canada (HPG) as the Creative Director for many monthly, quarterly, and annual equine magazines. Her passion (read: obsession) for breeding, genetics, and equine pedigrees ran ever-increasingly deep, which lead her to create StallionCompare.com.
Beyond her equine pursuits, Natashya is the Creative Director & Co-Founder of a leading design agency known for its boutique, customer-focused approach. With her expertise, she blends creativity and technology to make a lasting impact in both horse breeding and design.
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