For autosomal recessive disorders, dogs with two copies of the variant are at risk of developing the condition. Dogs with one copy of the variant are considered carriers and are usually not at risk of developing the disorder. However, carriers of some complex variants grouped in this category may be associated with a low risk of developing the disorder. Individuals with one or two copies may pass the disorder-associated variant to their puppies if bred.
At risk dogs are highly likely to show signs of this disease in their lifetime.
Partner with your veterinarian to make a plan regarding your dog’s well-being, including any insights provided through genetic testing. If your pet is at risk or is showing signs of this disorder, then the first step is to speak with your veterinarian.
Subacute Necrotizing Encephalopathy, which resembles Leigh syndrome in humans, is a neurodegenerative disorder that is characterized by focal, bilaterally symmetric, necrotic lesions in the central nervous system. Affected dogs can present with a variety of clinical signs which range in severity. Additionally, affected dogs may have signs present acutely or as a chronic history of slowly progressing signs. Diagnosis is often made before 1 year of age but can span between the ages of 6 months to 3 years. Dogs affected with SNE appear neuropathologically similar to Alaskan Husky Encephalopathy (AHE). Characteristic signs include generalized seizures, altered mentation, behavioral changes, dysphagia (eating difficulties), loss of vision, hypermetria (overreaching movements), ataxia (uncoordinated movements), and tetraparesis (weakness in voluntary movement of all four limbs).
As there is no cure for this disorder, therapy is limited to symptomatic treatments and general supportive care. The progression of clinical signs should be carefully monitored, ensuring an affected dog is as comfortable as possible. The average prognosis is considered poor for affected dogs and, based on welfare grounds, euthanasia is often elected within months of the onset of clinical signs.
There are many responsibilities to consider when breeding dogs. Regardless of test results it is important that your dog is in good general health and that you are in a position to care for the puppies if new responsible owners are not found. For first time or novice breeders, advice can be found at most kennel club websites.
This disorder is autosomal recessive, meaning two copies of the variant are needed for a dog to be at an elevated risk for being diagnosed with the condition. A carrier dog with one copy of the Leigh-Like Subacute Necrotizing Encephalopathy (Discovered in the Yorkshire Terrier) variant can be safely bred with a clear dog with no copies of the Leigh-Like Subacute Necrotizing Encephalopathy (Discovered in the Yorkshire Terrier) variant. About half of the puppies will have one copy (carriers) and half will have no copies of the variant. Puppies in a litter which is expected to contain carriers should be tested prior to breeding. Carrier to carrier matings are not advised as the resulting litter may contain affected puppies. Please note: It is possible that disorder signs similar to the ones associated with this Leigh-Like Subacute Necrotizing Encephalopathy variant could develop due to a different genetic or clinical cause.
All coordinates reference CanFam3.1
Drögemüller, M., Letko, A., Matiasek, K., Jagannathan, V., Corlazzoli, D., Rosati, M., … Drögemüller, C. (2020). SLC19A3 loss-of-function variant in Yorkshire terriers with Leigh-like subacute necrotizing encephalopathy. Genes (Basel), 11(10), 1215. View the article