Progressive Retinal Atrophy (PRA) in Dogs: What Every Breeder Needs to Know

PRA causes progressive blindness — but it is preventable through responsible breeding and DNA testing

Progressive Retinal Atrophy is not a single disease. It is a family of inherited conditions that cause the photoreceptors in the retina to degenerate over time, eventually leading to complete blindness. There is no treatment and no cure. But it is almost entirely preventable through DNA testing and informed breeding decisions.

What Happens With PRA?

In dogs with PRA, the rod photoreceptors (responsible for night vision and peripheral vision) begin to deteriorate first. Affected dogs typically show early signs of night blindness — reluctance to go into dark rooms, bumping into objects in low light. As the condition progresses, daytime vision also fails as the cone photoreceptors are lost.

The progression varies by form and breed, but most affected dogs are significantly vision-impaired by middle age and completely blind by 7-10 years — or earlier in some forms. There is no reversal once degeneration begins.

Why PRA Is a Genetics Problem

Most forms of PRA are caused by specific mutations in genes involved in photoreceptor function. Because these mutations are identifiable, DNA tests can determine whether a dog carries them before any vision loss occurs.

The vast majority of PRA forms are autosomal recessive — meaning a dog must inherit two copies of the mutation (one from each parent) to be affected. Dogs with one copy are carriers: they are genetically unaffected but can pass the mutation to offspring.

A carrier bred to another carrier produces:

PRA Forms and the Breeds They Affect

PRA is not caused by a single gene — different breeds have different mutations:

prcd-PRA (progressive rod-cone degeneration) — The most common and widespread form. Affects Labrador Retrievers, Golden Retrievers, Cocker Spaniels, Miniature and Toy Poodles, Portuguese Water Dogs, Miniature Schnauzers, and many others. Tested for on most DNA panels.

PRA-rcd1 — Irish Setters and Gordon Setters

PRA-rcd2 — Collies and related breeds

PRA-crd (cone-rod dystrophy) — Staffordshire Bull Terriers, American Staffordshire Terriers

XLPRA (X-linked PRA) — Siberian Huskies and Samoyeds. X-linked inheritance means males are more frequently affected.

PRA-rcd4 — Gordon Setters, Irish Setters, Irish Glen of Imaal Terriers

Cord1-PRA — Miniature Longhaired Dachshunds

PRA in Poodles — Multiple forms exist: prcd is most common, but others (erd, rcd4, etc.) have also been identified. This is why a full Poodle PRA panel is important.

DNA Testing: What Results Mean

Most canine DNA panels test for the most common PRA mutations relevant to specific breeds. Results are reported as:

Clear (Normal) — The dog has no copies of the tested mutation. It cannot pass that mutation to offspring.

Carrier — The dog has one copy of the mutation. It will not develop PRA from this mutation but can pass the allele to offspring. A carrier bred to a clear dog produces all clear or carrier puppies — no affected offspring.

Affected — The dog has two copies of the mutation and will develop PRA if it lives long enough.

Breeding Decisions With PRA Results

Ideal: Only breed clear dogs to clear dogs. This eliminates PRA from the litter entirely for the tested mutation.

Acceptable: Carrier bred to clear. No affected puppies are produced, though 50% of offspring may be carriers. This is a responsible approach for preserving other valuable traits in a carrier dog.

Never: Affected bred to any dog produces 50-100% carriers and potentially affected offspring. Affected dogs should not be bred.

Never: Carrier to carrier. This produces approximately 25% affected offspring.

Important Limitations of PRA Testing

DNA tests only detect the specific mutations they test for. A dog that is "PRA clear" on a panel may still carry an untested mutation. This is why breed-specific panels matter — a panel designed for Labrador Retrievers tests for the mutations known to occur in Labs, not every PRA mutation in all breeds.

Additionally, eye examinations (CAER exams through OFA) can detect early signs of retinal disease that may not yet be captured by a genetic test. Both genetic testing and ophthalmic exams are components of a complete health program.

What to Ask a Stud Dog Owner

When selecting a stud dog, ask:

  1. Has he been DNA tested for PRA? Which panel and which lab?
  2. What were his results for each PRA mutation tested?
  3. Does he have a current CAER eye exam through OFA?

A responsible stud owner will have this information readily available and be able to provide documentation.

Summary

PRA is a group of inherited diseases causing progressive blindness in dogs. Most forms are autosomal recessive and detectable through DNA testing. Clear dogs can safely be bred to carriers without producing affected offspring. DNA test every breeding dog for PRA mutations relevant to their breed. Ask for documentation before committing to a stud. PRA blindness is preventable — there is no excuse for producing affected puppies when testing is widely available.