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

Early-Onset Progressive Retinal Atrophy (EOPRA) is an eye disorder where the light sensing retina at the back of the eye deteriorates, causing impaired vision. The associated genetic variant has been identified in the Spanish Water Dog, and affected dogs are typically diagnosed with progressive vision loss before 4 years of age.

Key Signs

Progressive vision loss, Night blindness, Retinal degeneration

Age of Onset

1 to 4 yrs

Junior to adult onset

Inheritance

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

Moderate-high likelihood

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

What to Do

Here’s how to care for a dog with EOPRA

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 EOPRA

Early-Onset Progressive Retinal Atrophy in Spanish Water Dogs is typically diagnosed before the age of 4 years, with initial clinical signs noted by owners around the ages of 2 and 3 years. However, the slowly progressive change in vision may not be obvious in some cases. Dogs affected by EOPRA show standard PRA clinical expression, such as initial hyper-reflectivity of the fundus (back surface 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, many dogs adapt remarkably well to the loss of vision. Owners may find that it is helpful to keep the dog's main environment as stable as possible (avoid moving furniture, etc.) to help them navigate as vision worsens. Some dogs may exhibit a tentativeness when introduced to unknown environments, especially in low light conditions, because of their compromised vision.

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.

This disorder is autosomal recessive, meaning two copies of the variant are needed for a dog to be at an elevated risk for being diagnosed with the condition. A carrier dog with one copy of the Early-Onset Progressive Retinal Atrophy, (Discovered in the Spanish Water Dog) variant can be safely bred with a clear dog with no copies of the EOPRA, (Discovered in the Spanish Water Dog) variant. About half of the puppies will have one copy (carriers) and half will have no copies of the variant. Furthermore, a dog with two copies of the EOPRA, (Discovered in the Spanish Water Dog) variant can be safely bred with a clear dog. The resulting puppies will all be carriers. 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 disorder signs similar to the ones associated with this EOPRA variant could develop due to a different genetic or clinical cause.

Technical Details

Gene PDE6B
Variant Deletion
Chromosome 3
Coordinate Start 91,749,865
Coordinate End 91,749,870

All coordinates reference CanFam3.1

References & Credit

Credit to our scientific colleagues:

Winkler, P.A., Ramsey, H.D., Petersen-Jones, S.M. (2020). A novel mutation in PDE6B in Spanish Water Dogs with early-onset progressive retinal atrophy. Vet Ophthalmol, 23(5), 792-796. View the article