What is progressive retinal atrophy?
Progressive retinal atrophy (PRA) is a group of eye diseases featuring the gradual degeneration of the retina. Each type has a different genetic cause. Aussies are known to have a form of PRA called progressive rod cone degeneration (prcd.) No other type appears to be present in the breed.
What is progressive rod cone degeneration (PRCD)?
It is the most common form of PRA in dogs and the only one found in Aussies. PRCD causes the gradual degeneration of the rods and cones, the sensory cells lining the back of the eye. PRCD arises in mature adults. The first sign you notice may be night blindness but over time the dog will eventually lose all its vision. Both eyes will be affected.
How can I tell if my dog has PRCD?
If your dog seems to be having trouble seeing things at night or in low light levels, get it to a veterinary ophthalmologist for an exam. The vet will dilate the eyes and inspect the retina. PRCD may require more than one exam spaced a few months or more apart to make a diagnosis. If PRCD is suspected there is a DNA test that can confirm the diagnosis.
What does PRCD mean for my dog?
Unfortunately, there is no treatment and your dog will gradually go blind. Most dogs adjust very well to loss of vision. A dog’s senses of smell and hearing are more important to the way it perceives the world than its eyesight. The disease does not cause the dog any pain. You will need to keep in mind that your dog’s vision is going and take steps to protect him from dangers he might not be aware of.
How common is PRCD in Aussies?
Fewer than 1% are affected. It is likely that somewhere between 5 and 10% are carriers.
Is PRCD inherited?
Yes. PRCD is recessive, so a dog has to have two copies of the mutation to have the disease. Both of its parents must have at least one copy. Dogs with only one copy will be healthy carriers.
Is there a DNA test?
Yes. Results will indicate whether your dog has one, two, or no copies of the mutated version of the PRCD gene. Dogs with two copies will become affected during adulthood. Dogs with one copy of the mutation are healthy carriers. If your dog does not have the mutation it is clear of PRCD.
What dogs should be tested?
Any Aussie that is thought to be affected with PRA should have the PRCD test. First-step relatives (parents, full and half siblings, and offspring) of affected dogs and those found to have two copies of the mutation who will be used for breeding or whose owners want to know if they will develop PRCD should be tested. Parents and offspring, and full siblings of a dog found to have one copy of the mutation should be tested; when it is determined which parent is the source of the mutation the half-siblings through that parent should also be tested. There is no need to test dogs whose parents have both tested clear.
What does PRCD mean for my breeding program?
Affected dogs and those with two copies of the mutation it should not be bred. Dogs with one copy may be bred but only to dogs that have tested clear. Their offspring which might be bred will need to be tested so their PRCD status is known.