Clinical signs appear between six and eleven months of age. The signs are progressive in nature and include gait abnormalities; behavioral changes such as dullness, nervousness, or abnormal vocalization; incontinence; and uncontrolled defecation. Affected dogs may also show compulsory pacing, visual deficits, nystagmus, head tilt and neurological deficits, predominantly related to sensory localization. Neurological examination may show a mild head tilt, generalized cerebellar ataxia, hypermetria of the thoracic limbs, a depressed patellar reflex, proprioceptive deficits, decreased menace, visual deficits, positional nystagmus, and decreased muscle tone. A characteristic pathologic feature for the disease is the development of spheroids in the grey matter of the cerebral hemispheres, the cerebellum, the brain stem, and in the sensory pathways of the spinal cord.

Treatment is supportive care, however, due to the progressive nature of the condition, clinical signs typically lead to euthanasia before two years of age on welfare grounds.

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 disease is autosomal recessive meaning that two copies of the mutation are needed for disease signs to occur. A carrier dog with one copy of the NAD mutation can be safely bred with a clear dog with no copies of the NAD mutation. About half of the puppies will have one copy (carriers) and half will have no copies of the NAD mutation. 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 disease signs similar to the ones caused by the NAD mutation could develop due to a different genetic or clinical cause.