Neuronal Ceroid Lipofuscinosis 8 (Australian Shepherd Type)

Common Symptoms

Neuronal ceroid lipofuscinosis 8 (Australian shepherd type) is a lysosomal storage disease affecting dogs. Affected dogs lack a specific Enzyme necessary for normal cellular metabolism. As a result, there is an abnormal accumulation of waste compounds primarily in the cells of the nervous system, leading to a range of nervous system disorders. In affected dogs poor vision may be noticed as puppies, but as early as 10-12 months of age symptoms of cognitive decline appear and may include loss of learned behaviors, circling, and pacing. Symptoms progress to blindness, Ataxia, behavior changes such as anxiety and aggression, tremors, sensitivity to touch and sound, and seizures by the time the dog is 2 years of age. Affected dogs are typically euthanized due to disease progression.

Breed-Specific Information for the Toy Australian Shepherd

Toy Australian shepherd is included as a breed susceptible to neuronal ceroid lipofuscinosis 8 (Australian shepherd type) because of its close relatedness to the Australian shepherd breed, which is known to develop this disease due to Mutation of the CLN8 gene. The frequency of the causal mutation in the general toy Australian shepherd population is unknown.

Testing Tips

Genetic testing of the CNL8 gene in toy Australian shepherds will reliably determine whether a dog is a genetic Carrier of neuronal ceroid lipofuscinosis 8 (Australian shepherd type). Neuronal ceroid lipofuscinosis 8 (Australian shepherd type) is inherited in an Autosomal Recessive manner in dogs meaning 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 that is 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 CNL8 gene mutation. Reliable genetic testing is important for determining breeding practices. In order to eliminate this mutation from breeding lines and to avoid the potential of producing affected pups, breeding of known carriers to each other is not recommended. Toy Australian shepherds that are not carriers of 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.

References

• Guo J, Johnson GS, Brown HA, Provencher ML, da Costa RC, Mhlanga-Mutangadura T, Taylor JF, Schnabel RD, O'Brien DP, Katz ML. A CLN8 nonsense mutation in the whole genome sequence of a mixed breed dog with neuronal ceroid lipofuscinosis and Australian Shepherd ancestry. Mol Genet Metab. 2014 Aug;112(4):302-9 [PubMed: 24953404]
• O'Brien DP, Katz ML. Neuronal ceroid lipofuscinosis in 3 Australian shepherd littermates. J Vet Intern Med. 2008 Mar-Apr;22(2):472-5 [PubMed: 18371036]