Progressive Retinal Atrophy
Sometimes clients and patients become friends, and this can make breaking bad news more difficult than normal — and it’s never easy. This was the case with a gentleman and his two dogs I worked with when I practiced in Wyoming. I think I must have seen his two chocolate labs at least once monthly, what with all the routine care, nail trims, anal gland expressions and boarding we provided (the owner travelled a lot on business).
One day I saw him and his male lab on the appointment schedule for an "eye check." I walked into the exam room expecting the red, weepy eye that is often caused by allergies, an injury, something stuck under the third eyelid, etc., but at first glance, the dog’s eyes looked perfectly normal. Then, the owner started talking about how his dog seemed to be having trouble with his vision recently, particularly in the dark. My reaction was, "oh sh&#."
Rather quickly I diagnosed the dog with progressive retinal atrophy (PRA), a genetic condition that almost invariably leads to blindness. It is all-too-common in labs and other pure-breed dogs, including poodles, cocker spaniels, collies, Irish setters, dachshunds, miniature schnauzers, akitas, Australian shepherds, golden retrievers, samoyeds, beagles, German shepherd dogs, Siberian huskies, Yorkshire terriers, and Portuguese water dogs.
As the name suggests, PRA is a disease that affects the eyes' retinas. The retina contains photoreceptors, special cells responsible for converting light into electrical nerve signals that then travel to the brain.
There are two separate types of photoreceptors in the retina: cones, which are primarily associated with color vision, and rods, which are involved in black and white and low-light vision. When a dog has PRA, his photoreceptors deteriorate over time and eventually he becomes blind. Typically, the rods are the first to go, which is why dogs have problems with night vision in the early stages of PRA.
Progressive retinal atrophy can usually be diagnosed with an eye exam. The characteristic changes caused by the disease are visible in the back of the eye when using an ophthalmoscope. If there are any questions regarding the diagnosis, referral to a veterinary ophthalmologist is certainly called for.
There is no treatment for PRA. The silver lining is that dogs deal extremely well with blindness, as long as they have owners who are dedicated to providing a consistent and safe environment for them by following a few simple guidelines:
- Keep the food and water dishes, dog beds, toys, etc., within easy reach and in their expected locations.
- Do not move furniture around unless absolutely necessary. If you have made a change, show your dog the new configuration by slowly guiding him through it.
- Use baby gates to prevent falls down stairs or entry into other potentially dangerous locations.
- Only let your dog loose in a fenced yard. Leash walks are still okay, although many dogs seem to prefer traveling over familiar ground rather than exploring new territories.
- Limit the changes your dog has to adapt to. For example, a blind dog would probably do better remaining at home being taken care of by a familiar pet sitter versus traveling to Grandma’s house for Thanksgiving with the extended family
I left Wyoming before my lab patient became completely blind, but he was adapting well to his declining vision. Odds are he’s still going strong five years later.
Dr. Jennifer Coates