DNA testing for early onset progressive retinal atrophy (EOPRA) in dogs

Progressive retinal atrophy is a canine health condition that causes a slowly developing progressive blindness in dogs, which cannot be reversed or cured. Whilst progressive retinal atrophy is painless, the associated loss of vision that it causes is of course very limiting for dogs and their owners, and can cause total blindness and all of the complications that this entails.

Progressive retinal atrophy tends to develop largely in dogs that are mature or approaching their senior years, but this is not always the case – and progressive retinal atrophy comes in various different types, one of which is known as EOPRA, or early onset progressive retinal atrophy. As you might expect, EOPRA develops much earlier on in the affected dog’s life, usually beginning to show symptoms in pups that are just a few months old.

Early onset progressive retinal atrophy, like other forms of progressive retinal atrophy, is a hereditary health condition that is passed from dog to dog by means of the inheritance of certain faulty genes. This means that EOPRA is more prevalent within certain dog breeds than others.

Within the UK, the Portuguese water dog is considered to be a higher-than-normal risk breed for EOPRA, and Optigen, one of the UK’s leading canine DNA labs, has recently introduced an EOPRA test for dogs, to enable breeders and dog owners to determine the status of their own pets.

In this article we will examine how EOPRA can be passed on from dogs to their offspring, why the Portuguese water dog is at higher risk of EOPRA, and how to find out the status of any given dog. Read on to learn more.

What is early onset progressive retinal atrophy?

Early onset progressive retinal atrophy is a specific type of progressive retinal atrophy that develops within younger dogs, in contrast to most types of progressive retinal atrophy, which tend to occur later in life.

The early onset variant of progressive retinal atrophy is also sometimes known as retinal dysplasia, and this tends to present with symptoms for the first time in puppies who have yet to reach the six months old milestone, although it can develop a little later.

Dogs with early onset progressive retinal atrophy tend to progress to full or almost-full blindness within a fairly short period of time too, usually much quicker than is the case in other presentations of the condition, when it can take months or even years to really have a significant impact on the dog’s vision.

Early onset progressive retinal atrophy in dogs cannot be prevented or cured, but it does not cause any pain or other problems for dogs with the condition. However, caring for a dog that is blind or whose vision is failing can be a challenge, as they require extra care and consideration to keep them safe and happy.

Why is the Portuguese water dog at risk of inheriting early onset progressive retinal atrophy?

Early onset progressive retinal atrophy is a hereditary disorder, and this means that it the status of any given dog’s two parents that dictates their risk factors for the condition. Because the number of unique, unrelated dogs that form the breeding stock of any pedigree dog breed is limited to only dogs of the same breed, this means that the chances of a genetic mutation or flaw that causes a certain type of problem or health condition spreading across the gene pool is greater.

This in turn means that hereditary health conditions can spread quite quickly (over the course of just a few generations of dogs) across specific breeds, and within the Portuguese water dog breed, early onset progressive retinal atrophy is one such condition.

How is early onset progressive retinal atrophy passed from dog to dog?

Early onset progressive retinal atrophy is passed on to dogs that inherit a combination of gene faults from both sides of their lineage.

Early onset progressive retinal atrophy spreads by means of autosomal recessive heredity, which means that the status of both of a dog’s parents dictates their own status for the condition as follows:

• Two clear parent dogs will produce a litter that is itself clear of the condition.
• Two affected parent dogs will produce an affected litter.
• Two carrier parent dogs will produce a litter of 50% carriers, 25% affected and 25% clear.
• A carrier and an affected dog will produce a litter of 50% carriers and 50% affected.
• A carrier and a clear dog will produce a litter of 50% carriers and 50% clear.
• A clear dog and an affected dog will produce a litter of carriers.

Getting your dog DNA tested for EOPRA

If you are considering breeding from your Portuguese water dog and are trying to find a good mating match, you are strongly advised to have your dog (and their mating match) tested for their EOPRA status first.

The test for EOPRA is a simple DNA test, which means that you just need to ask your vet to take a DNA sample from your dog, which they will then send way to the Optigen lab for testing, before a report is returned to you identifying your dog as clear, a carrier, or affected.

If you are considering buying a Portuguese water dog puppy, you should ask the breeder about their health testing protocols, and ask to see results on the status of the parent dogs.

Whilst early onset progressive retinal atrophy tends to become symptomatic well before the dog in question reaches breeding age, which means that responsible breeders won’t keep such dogs for breeding, carrier dogs that are not affected by the condition themselves can still pass on markers for the condition to their own offspring.

This has implications if you intend to breed from the pup that you are buying in the future, and may also mean that a dog with untested parents might still inherit the affected form of the condition if two carrier dogs are bred together.