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.
Light sensitive retinal photoreceptors of affected puppies fail to develop appropriately shortly after birth, with retinal abnormalities appearing between 3 and 10 weeks of age. Electroretinograms will show an absent b-wave, indicating abnormal transmission to secondary neurons. The first clinical sign is night blindness, usually appearing around 6 weeks of age. Early retinal degeneration (ERD) progresses rapidly until about 6 months of age, at which time it becomes more gradual as hybrid rod/cone photoreceptors are formed. Affected dogs typically become completely blind by 12 to 18 months of age.
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). Owners may find that it is helpful to keep the dog's main environment as stable as possible (avoid moving furniture, etc.) to help them navigate as vision worsens.
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 ERD mutation can be safely bred with a clear dog with no copies of the ERD mutation. About half of the puppies will have one copy (carriers) and half will have no copies of the ERD 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 ERD mutation could develop due to a different genetic or clinical cause.
All coordinates reference CanFam3.1
Goldstein, O., Kukekova, A. V., Aguirre, G. D., & Acland, G. M. (2010). Exonic SINE insertion in STK38L causes canine early retinal degeneration (erd). Genomics. View the article