Progressive retinal atrophy is the name of a group of hereditary diseases that involve
degeneration of the retina, and eventual blindness.

There are many different forms of PRA , and each of the forms are the result of a specific hereditary defect.

At this time, there is no treatment for PRA.

What is Progressive Retinal Atrophy (PRA)

• Progressive retinal atrophy is the name of a group of hereditary diseases that involve
  degeneration of the retina, and eventual blindness.
• At this time, there is no treatment for PRA.
• There are many different forms of PRA , and each of the forms are the result of a specific hereditary defect. The disease is inherited, and occurs in both eyes (bilateral). Pure-bred dogs are most commonly affected, and specific breeds are predisposed to
  specific types of PRA (see Breed Specific Information section below).
• Despite the form of PRA, most dogs present with similar clinical signs. The age of onset will vary between breeds.
• Diagnosis of PRA by your veterinarian can be made with an eye exam, and an electro-retinogram (ERG, detects activity of the retina). Diagnosis can be assisted with genetic testing (see Genetic Testing section below).

Signs

• Impaired night vision, nyctalopia
• Dilated, non-responsive pupils
• Increased tapetal reflection, or “eye shine”
• Cataracts (late in the disease)
• Eventual blindness

Breed-Specific Information

• prcd-PRA (Progressive Rod-Cone Degeneration)

This form of PRA is the most common form. Rod cells degenerate first, causing night blindness. It is a recessive trait, which requires that both parents pass on a mutant, disease-causing gene. Parents can either be carriers (1 mutant gene, 1 normal gene), or affected animals (2 mutant genes). There is a genetic test available for this form of PRA in the American & English Cocker Spaniels, American Eskimo, Australian Cattle Dogs, Australian Shepherds, Australian Stumpy Tail Cattle Dogs, Chesapeake Bay & Labrador Retrievers, Chinese Cresteds, Cockapoos, Entlebucher Mountain Dogs, Finnish & Swedish Lapphunds, Kuvasz, Labradoodles, Lapponian Herders, Miniature & Toy Poodles, Nova Scotia Duck Tolling Retrievers, Portuguese Water Dog, & the Spanish Water Dog. The test requires a blood sample. prcd-PRA can be prevented through strategic breeding of tested dogs.

• Dominant PRA of Mastiffs & Bullmastiffs

Mastiffs & Bullmastiffs are the only breeds known to be affected with a dominantly-inherited form of PRA. This means that only one copy of the mutant gene is required to cause the disease. Genetic testing can identify a dog as normal, heterozygous affected (1 mutant gene, 1 normal gene), or homozygous affected (2 mutant genes). About 50% of the puppies of a heterozygous animal will be affected, and 100% of the puppies of homozygous animals will be affected.

• Other Forms of PRA

Welsh Corgis are affected by a form of PRA called rcd3-PRA (rod & cone degeneration type 3). Irish Setters can be affected by rcd1-PRA. The mutation in Miniature Schnauzers is called Type A-PRA, because there are multiple causes in this breed. In Samoyeds and Siberian
Huskies the disease is X-linked (on the X chromosome). This form is called XL-PRA.