Several dog breeds inherit an eye disease called Progressive Retinal Atrophy (PRA), which was formerly called generalized retinal atrophy. The disease results in a progressive loss of photoreceptor cells which are responsible for vision.
The condition has been found in over 100 dog breeds.
PRA does not cause pain and is not life-threatening. At first, dogs with the condition have trouble seeing in dim light or at night. Gradually they lose their ability to see during the daytime, and then become completely blind.
Diagnosis is usually delayed since dogs cope well with gradual vision loss. Owners may not notice until something in your home such as furniture is moved and your dog keeps on bumping into it.
Since the disease is inherited, if your dog is diagnosed with PRA than others in the same lineage should be examined. Genetic tests can be used to see if a dog is a carrier. There is a test called an electroretinogram (ERG) that tests the retina and determines if it is functioning normally.
The age when the disease starts and the rate that it worsens varies by breed. Since there is no treatment, the goal is to help your dog adjust to the onset of blindness such as minimizing changes in your dogs environment so they are familiar with how to get around.
Symptoms of PRA
You might notice that the pupils of your dog's eyes become dilated and look like they are reflecting more light.
The eyes might appear cloudy causing a diagnosis of cataracts, when in fact the PRA is the cause.
Diagnosis of PRA
Your veterinarian will have your dog walk an obstacle course to determine if he or she can negotiate the course in both bright and dim light.
By examining the base of the eye your vet might notice a granular appearance and a thinning of the retina. Clinical examination will look for changes in eye color (pigmentation changes) and a weakening of the optic nerve in both eyes.
An electroretinogram (graph of electrical activity in the retina) can help to diagnose the condition early.
For Toy Poodles a PRA test is offered by
Progressive Rod Cone Degeneration (PRCD)
This is the genetic form of progressive retinal atrophy seen in poodles and other breeds.
Common breeds affected:
- Miniature Poodles
- Toy Poodles
- Labrador Retrievers
- English Spaniels
- American Cocker Spaniels
- Portuguese Water Dogs
- Chesapeake Bay Retrievers
- Australian Cattle Dogs
- Nova Scotia Duck Tolling Retrievers
type of PRA that affects these dogs happens later in the dog's life. The
exact age and the rate the disease progression differs between breeds.
Diagnosis and Treatment of Ocular Fundus Disorders of Geriatric Dogs
College of Veterinary Medicine, North Carolina State University
Raleigh, NC, USA