Progressive Retinal Atrophy (PRA) in Labradors

If you have a Labrador, progressive retinal atrophy (PRA) is the eye disease worth knowing. It slowly damages the part of the eye that senses light. The good news: a DNA test has helped make the gene behind it much rarer in the breed [2].

What is progressive retinal atrophy (PRA)?

• A group of inherited diseases in which the light-sensing cells of the retina slowly wear out [1].
• In Labradors, one well-known form is caused by a change in a gene called PRCD. It is known as prcd-PRA [2][3].
• Dogs are born with normal sight. Night blindness usually comes first, and complete blindness typically follows within one to two years of the first signs [2].
• Cataracts often develop later in the disease [1].

Is PRA genetic or contagious?

It is genetic, not an infection, so it doesn't spread between dogs [1][2][3].

• A dog develops the disease only if it inherits two copies of the gene change, one from each parent [2][3].
• A dog with one copy is a healthy carrier, but it can pass the gene on to its puppies [2][3].
• Carriers show no signs, so they can be bred without anyone knowing [2].

Which dogs get prcd-PRA?

The PRCD gene is linked to PRA in Labradors, Poodles (Toy and Miniature), Cocker Spaniels (American and English) and Portuguese Water Dogs [2]. The same gene change matched the disease in 18 breeds or breed varieties tested [3].

At what age do signs start?

Sources describe it slightly differently. One genetics database says signs usually begin in adolescence or early adulthood [2]. Merck's manual lists the Labrador among breeds where signs tend to appear later, around 3 to 5 years [1]. Either way, the change is gradual.

What are the first signs of PRA?

Early signs are linked to poor night vision [1][2]:

• Reluctance to move around in dim light or at night.
• Bumping into familiar furniture, especially after dark.
• Hesitating on stairs or before going into a dark room.
• These signs slowly get worse over weeks to months, and daytime sight is affected later [1][2].

See a vet quickly: if your dog loses its sight suddenly rather than slowly, have it checked promptly. Sudden blindness can have other causes, some of them urgent [1].

Only a licensed vet can find the reason behind these signs.

Is there a DNA test for PRA in Labradors?

Yes. A DNA test for the PRCD gene change shows whether a dog is clear, a carrier or affected. It is used to guide breeding decisions [2][3].

And it works. After the test became available, the gene change fell from 7.8% to 0.3% in the Labrador population studied [2].

• Ask the breeder for the parents' PRCD test results, or a recent eye exam [2][3].
• The breed standard says only "functionally and clinically healthy dogs" should be bred [4].

What a test result means for your own dog is a question for your vet.

FAQ

Can two healthy parents have a puppy with PRA?

Yes, if both are carriers. Carriers look healthy, and a puppy is affected when it inherits one copy from each parent [2][3].

Does PRA lead to total blindness?

It usually does. Complete blindness typically follows within one to two years of the first signs [2].

What should I ask a Labrador breeder about PRA?

Ask whether both parents were DNA-tested for prcd-PRA, and ask to see the results [2][3].