NCL, also sometimes called Canine Ceroid Lipofusciosis, is a storage disease—toxins that the body normally would eliminate as waste build up in certain tissues. In this case, it happens in the nervous system. Affected dogs start showing signs around a year and a half of age. They have seizures, but may also lose their eyesight, exhibit circling behavior, dementia and aggression. The disease kills the dog by the time it is 2-3 years old. NCL is inherited in some breeds. Thankfully, it is extremely rare in Aussies.
Diagnosis of NCL can be difficult. The only definitive test is through examination of nervous system tissue upon necropsy or a DNA test. Levels of carnitine in the blood may be reduced, but this alone is not conclusive.
Epilepsy is a much more common disease in Aussies. It usually comes on at about the same age as NCL and is sometimes lethal. However, the other signs of NCL should enable the treating veterinarian to recognize that NCL seizures are due to something other than primary epilepsy.
Several genetically distinct forms of NCL have been identified and DNA tests are available. The NCL-causing mutation for NCL6 gene has been identified in a very small number of Australian Shepherds as has a different mutation for NCL8. It is possible that there might be more forms of NCL in the breed for which there are not presently DNA tests. If a dog is exhibiting symptoms of NCL and is negative for the available tests a necropsy may be necessary to confirm diagnosis.