Cerebellar Ataxia 2 (Belgian Shepherd Type)

Other Names: Spongy degeneration with cerebellar ataxia 2, SBCA2
Affected Genes: ATP1B2
Inheritance: Autosomal Recessive
Mutation: chr5:32551064-32551065 (canFam3): 277 bp SINE Insertion

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Common Symptoms

Cerebellar Ataxia 2 (Belgian Shepherd Type) is a progressive, early onset, inherited neurologic disease affecting the Belgian Sheepdog. Symptoms usually present as early as the first four weeks of life and progress quickly. Affected dogs are unable to regulate potassium in the central nervous system. Potassium is critical for proper nerve function. These dogs have difficulty controlling leg movements and keeping their balance. Owners may observe dogs stumbling, staggering, circling, pacing, experiencing tremors, and falling. Some dogs may present with seizures and blindness. Most affected dogs either die or are euthanized within weeks after presentation due to severity and progression of clinical signs.

Breed-Specific Information for the Belgian Sheepdog

The Mutation of the ATP1B2 gene associated with progressive, early onset, cerebellar Ataxia has been identified in the Belgian Sheepdog. Though the exact frequency in the overall Belgian Sheepdog population is unknown, 4% of the 25 Belgian Sheepdogs in one study were found to have one copy of this mutation.

Testing Tips

Genetic testing of the ATP1B2 gene in Belgian Sheepdogs will reliably determine whether a dog is a genetic Carrier of cerebellar Ataxia 2. This disease is inherited in an Autosomal Recessive manner in the Belgian Sheepdog. This means that they must receive two copies of the mutated gene (one from each parent) to develop the disease. In general, carrier dogs do not have features of the disease but when bred with another carrier of the same Mutation, there is a risk of having affected pups. Each pup born to this pairing has a 25% chance of inheriting the disease and a 50% chance of inheriting one copy and being a carrier of the ATP1B2 gene mutation. Reliable genetic testing is important for determining breeding practices. To eliminate this mutation from breeding lines and avoid the potential of producing affected pups, breeding of known carriers to each other is not recommended. Belgian Sheepdogs that do not carry the mutation have no increased risk of having affected pups.

There may be other causes of this condition in dogs and a normal result does not exclude a different mutation in this gene or any other gene that may result in a similar genetic disease or trait.


  • Mauri N, Kleiter M, Dietschi E et al: A SINE Insertion in ATP1B2 in Belgian Shepherd Dogs Affected by Spongy Degeneration with Cerebellar Ataxia (SDCA2). G3 (Bethesda) 2017 Vol 7 (8) pp. 2729-2737. [PubMed: 28620085]
  • Mauri N, Kleiter M, Leschnik M, et al: A Missense Variant in KCNJ10 in Belgian Shepherd Dogs Affected by Spongy Degeneration with Cerebellar Ataxia (SDCA1). G3 (Bethesda) 2017 Vol 7 (2) pp. 663-669. [PubMed: 28007838]