The age of onset of SDCA is usually 6-8 weeks. The first observable sign is poor coordination of movements (ataxia). Affected dogs may also suffer from episodic myokymia and/or seizures. Myokymia is characterized by uncontrollable twitching of the muscles that tends to run through a muscle in waves. Myokymia episodes can be precipitated by exercise or excitement. The condition can lead to neuromyotonia (generalized muscle stiffness). Neuromyotonia episodes are incapacitating attacks during which the dog becomes rigid and falls down. Affected dogs remain aware of their surroundings during neuromytonia attacks and are at risk of overheating. Long-term prognosis of this disorder is poor.

There is no curative treatment for the disease. Antiepileptic drugs can be used to decrease seizure activity but long-term prognosis is still poor.

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 develop. A carrier dog with one copy of the SDCA mutation can be safely bred with a clear dog with no copies of the SDCA mutation. About half of the puppies will have one copy (carriers) and half will have no copies of the SDCA 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 SDCA mutation could develop due to a different genetic or clinical cause.