Junior to adult onset
For autosomal recessive disorders, dogs with two copies of the variant are at risk of developing the condition. Dogs with one copy of the variant are considered carriers and are usually not at risk of developing the disorder. However, carriers of some complex variants grouped in this category may be associated with a low risk of developing the disorder. Individuals with one or two copies may pass the disorder-associated variant to their puppies if bred.
At risk dogs are highly likely to show signs of this disease in their lifetime.
Partner with your veterinarian to make a plan regarding your dog’s well-being, including any insights provided through genetic testing. If your pet is at risk or is showing signs of this disorder, then the first step is to speak with your veterinarian.
Generalized PRA is a late onset, slowly progressing eye disorder. The first sign of the disease is night blindness as a result of degeneration of reticular rod cells. Later cone cells also start to degenerate, impairing day vision. The first signs appear typically at the age of 2 to 5 years, and result in blindness over the course of the next two to three years.
Although this condition results in gradual vision loss, and eventual blindness, many dogs adapt remarkably well to vision loss. 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 develop. A carrier dog with one copy of the GPRA mutation can be safely bred with a clear dog with no copies of the GPRA mutation. About half of the puppies will have one copy (carriers) and half will have no copies of the GPRA 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 GPRA mutation could develop due to a different genetic or clinical cause.
All coordinates reference CanFam3.1
Dekomien, G., Vollrath, C., Petrasch-Parwez, E., Boevé, M. H., Akkad, D. A., Gerding, W. M., & Epplen, J. T. (2010). Progressive retinal atrophy in Schapendoes dogs: mutation of the newly identified CCDC66 gene. Neurogenetics, 11(2), 163–174. View the article