LOA Testing for Jack Russell & Parson Russell Terriers

Late Onset Ataxia (LOA) is a hereditary neurological condition that primarily affects Jack Russell and Parson Russell terriers. Caused by a mutation in the CAPN1 gene, it results in uncoordinated movement, a clumsy gait, and balance problems. Understanding LOA is vital for these breeds to ensure responsible breeding and better health outcomes.

What is Late Onset Ataxia?

LOA is a progressive condition affecting the spino-cerebellar region of the brain, which controls movement coordination. Symptoms usually appear between six and twelve months old and include initial stiffness in the back legs, difficulty negotiating stairs, and a characteristic “dancing” movement when standing still. As it progresses, affected dogs experience worsening incoordination and balance loss, which can severely impair their mobility and quality of life.

In some cases, progression stabilises early, allowing a dog to live reasonably well with management, but for others, the condition deteriorates, with euthanasia becoming the kindest option before two years of age to prevent suffering.

Who is at Risk?

LOA has been identified in both Jack Russell and Parson Russell terriers in the UK. Crossbreeds with one parent from these breeds can inherit the faulty gene and may be carriers or affected if they inherit the gene from both parents. Breeders must screen prospective breeding dogs for this gene mutation to prevent passing LOA to offspring.

How is LOA Inherited?

The condition follows an autosomal recessive pattern, with dogs being either clear, carriers, or affected. Understanding potential outcomes when breeding:

• Two clear dogs produce only clear puppies.
• Two affected dogs produce only affected puppies.
• Two carriers can produce 25% affected, 50% carriers, and 25% clear puppies.
• A clear and carrier pairing results in 50% carriers and 50% clear puppies.
• A clear and affected dog will have only carrier puppies.
• A carrier and affected pairing leads to 50% carriers and 50% affected puppies.

How to Test for LOA

Testing involves a simple DNA sample taken by your vet, either from blood or a buccal swab, sent to a Kennel Club approved laboratory. Results typically return within 3 to 5 working days. This testing allows breeders to make informed decisions and reduce LOA risk through selective breeding.

Latest 2025 Veterinary Insights

Current veterinary consensus in the UK continues to emphasise genetic testing as the best method to manage LOA in affected breeds. There are no treatments available to cure LOA, but early diagnosis can improve management of the condition. Ongoing research supports screening as essential to reducing disease prevalence in future generations.

An affected dog’s clinical signs commonly include loss of balance, a prancing or dancing gait, increasing difficulty walking, and frequent falls. Responsible breeders avoid breeding affected or carrier dogs to protect breed health.

Conclusion

Late Onset Ataxia is a serious hereditary condition in Jack Russell and Parson Russell terriers, but through awareness, responsible breeding, and genetic testing, its impact can be minimised. If you own or plan to breed these breeds, regular LOA testing is vital for the welfare of future puppies to ensure they lead healthy, happy lives.