Early-Onset Progressive Retinal Atrophy (Discovered in the Portuguese Water Dog)

Progressive retinal atrophy (PRA) is a disorder where the light sensing retina at the back of the eye degenerates resulting in vision loss.

Key Signs

Progressive vision loss

Age of Onset

1 to 4 yrs

Junior to adult onset


Autosomal Recessive

For autosomal recessive disorders, dogs with two copies of the variant are at risk of developing the condition. Dogs with one copy of the variant are considered carriers and are usually not at risk of developing the disorder. However, carriers of some complex variants grouped in this category may be associated with a low risk of developing the disorder. Individuals with one or two copies may pass the disorder-associated variant to their puppies if bred.

Likelihood of the Condition

High likelihood

At risk dogs are highly likely to show signs of this disease in their lifetime.

What to Do

Here’s how to care for a dog with PRA

Partner with your veterinarian to make a plan regarding your dog’s well-being, including any insights provided through genetic testing. If your pet is at risk or is showing signs of this disorder, then the first step is to speak with your veterinarian.

For Veterinarians

Here’s what a vet needs to know about PRA

Early-Onset Progressive Retinal Atrophy in Portuguese Water dogs is typically diagnosed before the age of 4 years, however the slowly progressive change in vision may not be obvious in some cases. Early-onset PRA in Portuguese Water Dogs shows standard PRA clinical expression, e.g. initial hyper-reflectivity of the fundus (back of the eye) due to the thinning retina as photoreceptor cells die, followed by attenuation of blood vessels that feed the retina. Eventually, as more of the photoreceptors die, the affected dogs become completely blind.

Although this condition results in gradual vision loss, and eventual blindness, many dogs adapt remarkably well to vision loss. Although there is no treatment, owners should be advised that the disease development is gradual and their dog may need assistance in unfamiliar surroundings as clinical signs progress.

For Breeders

Planning to breed a dog with this genetic variant?

There are many responsibilities to consider when breeding dogs. Regardless of test results it is important that your dog is in good general health and that you are in a position to care for the puppies if new responsible owners are not found. For first time or novice breeders, advice can be found at most kennel club websites.

Early-Onset Progressive Retinal Atrophy (Discovered in the Portuguese Water Dog) is autosomal recessive meaning that two copies of the mutation are needed for disease signs to develop. A carrier dog with one copy of the PRA mutation can be safely bred with a clear dog with no copies of the PRA mutation. About half of the puppies will have one copy (carriers) and half will have no copies of the PRA mutation. Puppies in a litter which is expected to contain carriers should be tested prior to breeding. Carrier to carrier matings are not advised as the resulting litter may contain affected puppies. Please note: It is possible that disease signs similar to the ones caused by the PRA mutation could develop due to a different genetic or clinical cause.

Technical Details

Technical details are not available at this moment.