The first signs of AHE are usually observed at the age of 6 months to 3 years of age. Affected dogs may have a sudden onset of clinical signs or a chronic history with slowly progressing signs. The characteristic signs of AHE include generalized seizures, altered mentation, behavioral changes, dysphagia (eating difficulties), loss of vision, hypermetria (overreaching movements), ataxia (uncoordinated movements), and tetraparesis (weakness in voluntary movement of all four limbs).

For affected dogs, the progression of clinical signs should be carefully monitored, ensuring the dog is as comfortable as possible. Affected dogs are usually euthanized within 2 to 7 months from the onset of clinical signs on welfare grounds, although some dogs may live for months to years before the signs progress.

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