The onset of clinical signs of PRA type III is typically at 5 years of age with initial loss of vision in dim light (night blindness) which gradually progresses to total blindness. The first signs are caused by loss of rod photoreceptor cells required for vision in dim light followed by reduction of the visual field and blindness as the cone cells of the retina also degenerate.

A blind dog tends to adapt well to the loss of vision. However, some dogs may exhibit a tentativeness when introduced to unknown environments because their vision is compromised. Occasionally, they may react abruptly (snapping) if they are startled so caution and use of verbal queues should be taken when handling a blind dog. Caretakers should take precautions to protect the blind dog from threats it cannot detect (ex. cliffs, sharp points on furniture, moving vehicles).

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