Progressive retinal atrophy is a group of inherited eye diseases that slowly destroy the cells of the retina. In the Coton de Tulear, the main form is called PRA-prcd, or progressive rod-cone degeneration. It comes on later in life and leads to blindness.
What happens in the eye
The retina has two main types of light-sensitive cells. Rods handle dim light and night vision. Cones handle bright light and colour. In PRA-prcd, the rods break down first, so night blindness is often the first sign. Over time the cones are affected too, and the dog loses daytime vision as well [citation:1].
Most affected dogs show noticeable vision loss by around four years of age, though the exact age and speed vary from dog to dog. In time, the disease usually leads to complete blindness [citation:1].
Signs to watch for
Early signs can be easy to miss. A dog may seem unsure in dim light, bump into things at dusk, or hesitate on stairs. Some owners notice a shine or reflection in the eyes. A veterinary ophthalmologist can often see changes in the retina before the dog shows obvious problems, using a special exam [citation:1].
If you notice any change in your dog's eyesight, even a small one, please write to us or call us. It is always better to have it checked.
How it is inherited
PRA-prcd is inherited in an autosomal recessive way. That means a dog needs two copies of the mutation to be affected. A dog with one copy is a carrier. Carriers do not develop the disease and look completely normal, but they can pass the mutation to their puppies [citation:1].
Two carriers bred together have roughly a one in four chance of producing an affected puppy. This is why testing matters before a litter is planned.
DNA testing
A DNA test is available for PRA-prcd. It uses a cheek swab or a blood sample and tells you whether a dog is clear, a carrier, or affected. The test is accurate for this specific form of PRA. It does not detect other, rarer forms of retinal disease, so a clear result for prcd does not rule out every possible eye problem [citation:1].
Results can be registered with the OFA. If you are buying a puppy, ask the breeder whether the parents were tested and whether you can see the results.
Breeding advice
The safest approach is to breed only clear dogs to clear dogs. That produces puppies that are all clear and cannot pass the mutation on.
If a carrier is bred, it should only be paired with a clear dog. That avoids producing affected puppies, though some of the litter may still be carriers. Breeding two carriers is not recommended [citation:1].
What the club recommends in 2026
PRA is one of the health tests the club encourages for breeding Cotons. As of 2026, DNA testing is widely available and affordable, and it remains the simplest way to avoid producing affected dogs. If you have questions about a test result, or you are not sure what it means for your dog, please write to us, call us, or come and visit us at a club event.
Source: UC Davis Veterinary Genetics Laboratory, Progressive Rod-Cone Degeneration (PRA-prcd).
