Hey there, pet parents. Today we're going to talk about a condition that affects one of our dogs' most precious senses: their sight. Progressive Retinal Atrophy (PRA) is a group of inherited diseases that cause a gradual, painless, and irreversible blindness in dogs. It can be a devastating diagnosis, but understanding the disease can help you prepare and adapt.
What is the Retina?
To understand PRA, we first need to know about the retina. The retina is a thin layer of tissue at the back of the eye that acts like the film in a camera. It's full of photoreceptor cells, called rods and cones, that detect light and send visual information to the brain.
- •Rods are responsible for vision in dim light (night vision).
- •Cones are responsible for vision in bright light and for seeing color.
What is Progressive Retinal Atrophy (PRA)?
In PRA, the rod and cone cells in the retina gradually begin to degenerate and die. "Atrophy" means the wasting away of a body tissue. "Progressive" means it happens over time.
In most forms of PRA, the rod cells are affected first. This means that the dog's night vision is the first thing to go. As the disease progresses, the cone cells also degenerate, eventually leading to complete blindness.
PRA is a genetic disease. It is inherited in many different breeds, and the specific gene mutation can vary from breed to breed. It is not a painful condition.
Spotting the Signs of PRA
Because PRA is a slow and gradual process, the early signs can be easy to miss.
- •Night Blindness (Nyctalopia): This is the first sign. Your dog may be more hesitant to go outside at night, may get lost in familiar rooms in the dark, or may bump into things in dim light.
- •Increased "Eye Shine": You might notice that your dog's eyes look more reflective in the dark. This is because the retina is thinning, which allows more light to be reflected back from the tapetum (the reflective layer behind the retina).
- •Dilated Pupils: The pupils may be more dilated than usual as the eye tries to let in more light.
- •Progressive Vision Loss: As the disease progresses, you will start to notice vision loss in the daytime as well. The dog may start bumping into furniture.
- •Cataracts: Many dogs with late-stage PRA will also develop secondary cataracts.
How Vets Diagnose PRA
If you or your vet suspect vision loss, you will be referred to a veterinary ophthalmologist (an eye specialist).
- •Ophthalmic Exam: The ophthalmologist will use special instruments to look at the back of your dog's eye. In a dog with PRA, they will see characteristic changes to the retina and the optic nerve.
- •Electroretinogram (ERG): This is the gold standard test for diagnosing PRA. It's a test that measures the electrical response of the cells in the retina to flashes of light. In a dog with PRA, the electrical response will be flat. This test can detect PRA even before the dog is showing obvious signs of blindness.
- •Genetic Testing: For many breeds, there is now a simple DNA test (usually a cheek swab) that can identify if a dog has the gene mutation for PRA. This is an invaluable tool for breeders to screen their dogs and avoid producing affected puppies.
Treatment and Management
This is the hard part: there is no cure for Progressive Retinal Atrophy. There is no medication or surgery that can stop or reverse the degeneration of the retina. The blindness is permanent.
The management of PRA is all about helping your dog to adapt to their vision loss and maintaining a great quality of life. And the amazing news is that dogs adapt to blindness incredibly well! They are much less dependent on their sight than people are, and they rely heavily on their amazing senses of hearing and smell.
Tips for Helping a Blind Dog:
- •Keep the Furniture in the Same Place: Don't rearrange your house. Your dog will create a mental map of their environment.
- •Use Scent Markers: You can use different essential oils to mark different rooms or important locations (like the water bowl).
- •Use Sound Cues: Talk to your dog frequently. Put a bell on your other pets (or on your own shoe) so your blind dog knows where everyone is.
- •Safety First: Block off access to stairs and swimming pools. When outside, always keep them on a leash.
- •"Scent" Your Way Home: On walks, allow your dog to sniff a lot. This helps them to create a scent map of the neighborhood.
Prognosis
While the prognosis for vision is poor (the dog will go blind), the prognosis for quality of life is excellent! Blind dogs can do almost everything that a sighted dog can do. They can play, they can cuddle, and they can live long, incredibly happy lives. The key is your patience and willingness to help them adapt.
Because PRA is a genetic disease, any dog diagnosed with PRA should not be used for breeding.
Sources & Further Reading:
- •American College of Veterinary Ophthalmologists - Progressive Retinal Atrophy
- 1VCA Animal Hospitals - Progressive Retinal Atrophy in Dogs