Progressive Retinal Atrophy (PRA)
Progressive Retinal Atrophy (also known as generalized progressive retinal atrophy or GPRA) describes an inherited disease of dogs that causes slowly progressive blindness over a period of months or years.

PRA can occur in almost any breed but is most commonly seen in miniature and toy poodles, cocker spaniels and Labrador retrievers. Other breeds less commonly affected include Tibetan terriers, miniature long-haired dachshunds and Yorkshire terriers, amongst others.

What will I notice?
The age at which an affected dog will develop signs of PRA will vary according to the breed but typically affects middle-aged dogs (3-8 years old). The first sign often noticed by owners is poor vision at night time or in dimly lit surroundings. The pupils may appear dilated and you may witness increased ‘eye shine’. Eventually, the dog will become completely blind but as the vision loss is gradual he or she will usually cope well and may not even seem blind to the owner. Occasionally, the first sign an owner may notice is a ‘cloudy eye’. This can occur when cataracts develop secondarily to the PRA.

How will I know if my pet has PRA?
Diagnosis of PRA is usually made by examining the back of the eye with an ophthalmoscope to look for characteristic signs of retinal degeneration. If the retina cannot be examined, for example if secondary cataracts are present, we may need to perform a test under a brief general anaesthetic. The test is called an ‘ERG’ (electroretinogram) and measures the electrical activity (and therefore function) of the retina.

DNA tests are also available for some breeds of dog. DNA tests are particularly useful in young dogs or those which may be used for breeding because the tests can identify affected dogs before they develop signs of PRA. They can also identify carrier animals, who will not develop PRA themselves but may pass the disease on to their offspring.

What can be done?
Sadly, at present at least, there is no effective treatment for PRA and affected animals are likely to become totally blind. Antioxidant therapy has been suggested to attempt to delay vision loss in affected animals but there is no evidence to suggest this to be effective. Current research into gene therapy may provide some hope for the future but treatment is a long way off at this stage.

As PRA is an inherited disease, affected animals should not be bred from. Many dogs cope very well with blindness, especially when it develops gradually as in PRA. You can make your pet’s adaptation to blindness easier, however, and we refer you to the advice sheet ‘Living with a blind dog’.