Progressive retinal atrophy is a disease that affects a dog's ability to see. There are different forms of progressive retinal atrophy or PRA, and eventually, dogs with this eye disease go blind. While not painful, PRA is definitely life-changing and should be understood by pet owners in order to best prepare for, and care for, a dog with this disease.
What Is It?
Progressive retinal atrophy primarily affects the cells of the retina called rods and cones but can also affect the pigmented cell layer below the rods and cones. Rods allow a dog to see movement and in low light conditions, cones allow a dog to see in color, and the pigmented epithelium layer helps to protect and maintain these rods and cones. In PRA, these rods, cones, and/or the pigmented layer deteriorates and is eventually worn away causing blindness. There are two main forms of progressive retinal atrophy that affect dogs but they are both considered to be hereditary.
- Generalized progressive retinal atrophy (GPRA): The most common form of PRA, generalized progressive retinal atrophy, can occur in both young and old dogs. In early-onset GPRA, the rods and cones have not properly developed and therefore the dog has problems seeing. In late-onset GPRA, the vision loss is gradual since the rod and cone cells formed correctly but instead deteriorate over time. This form of PRA isn't usually noticed until at least three years of age when a dog with this hereditary condition starts exhibiting signs of vision impairment.
- Central progressive retinal atrophy (CPRA): The less common form of PRA, central progressive retinal atrophy is also known as retinal pigment epithelial dystrophy (RPED). This rare type of eye disease causes the pigmented layer of the retina to deteriorate and therefore makes it difficult for a dog to see in low light. It is most often seen in older dogs and does not always cause complete blindness.
- Difficulty seeing at night or in low light
- Bumping into objects
- Difficulty seeing in bright light
- Getting lost in the dark
- Unable to find toys
- Unable to follow hand signals/commands
The most obvious signs of progressive retinal atrophy are directly related to a dog's ability to see well. Dogs that are starting to lose their ability to see may bump into objects that aren't normally in that specific spot. Stationery items or things that don't normally move around a dog's normal environment such as furniture and doorways are usually memorized so even blind dogs can navigate around them. But if a new coffee table is suddenly placed in the middle of a room, a dog with vision impairment may bump into it.
Nighttime and low light situations may also cause a dog with progressive retinal atrophy to have trouble seeing. You might be calling for your dog to come into the house at night while it is in the yard and it can't find its way back home. This is a regular occurrence in dogs with vision problems.
Ultimately complete blindness usually occurs in dogs with PRA. Your dog won't be able to find objects that it can't sniff out, may walk into walls in unfamiliar environments, and won't be able to pick up on body language cues from other animals or see hand signals to obey commands.
Progressive retinal atrophy is a hereditary condition that is seen in several breeds of dogs. In some breeds, it seems to be restricted to male dogs while in others it appears to be due to a dominant gene and is seen in both sexes.
Both purebred and mixed breed dogs can have PRA. Predisposed breeds that may be afflicted with early or late-onset GPRA include:
- Alaskan Malamute
- American Cocker Spaniel
- Belgian Shepherd
- Cardigan Welsh Corgi
- English Cocker Spaniel
- Glen of Imaal Terrier
- Irish Setter
- Labrador Retriever
- Miniature Schnauzer
- Poodle (Miniature and Toy)
- Portuguese Water dog
- Siberian Husky
- Tibetan Spaniel
- Tibetan Terrier
Breeds that may be afflicted with the rarer CPRA include:
- Border Collie
- Golden Retriever
- Labrador Retriever
- Shetland Sheepdog
European lines of these breeds also seem to be at a higher incidence rate. A specific gene mutation, called CNGB1, has been linked to PRA.
Gene therapy may offer dogs with PRA a cure by introducing a normal copy of the CNGB1 gene, according to Michigan State University, but this is not a widely available therapy or cure. Thankfully this is not a painful disease, so helping a pet navigate its new environment as it loses its vision is your best course of action if gene therapy is not an option. The layout of furniture should not change in a dog's home, blind dogs should be kept on a leash at all times when outside and extra care should be taken when walking a blind dog to ensure it does not run into walls or other objects.
Since it is a hereditary disease, progressive retinal atrophy is something that dogs can be born with if their parents had it. Selective breeding should be performed to eliminate dogs showing signs of PRA from the gene pool.