Heredity Diseases -PRA

In April 2025 a Brittany bitch was diagnosed with Progressive Retinal Atrophy (otherwise known as 'night blindness). This condition has never before been reported in Brittanys, either in the UK or France. However this does not mean that it has not occurred, as the symptom of gradual sight loss could just as easily be interpreted as resulting from old age.

In fact this is a hereditary condition where the blood supply to the retina (the lining inside the eyeball) slowly withers. This causes the outermost cells to die off, which are the ones that are most light sensitive. The dog will begin to operate less well in dull or dark conditions, and may react cautiously to shadows, or begin to bump into furniture that has been moved. As the blood vessels continue to atrophy, so the area of the retina that is affected increases, until the dog will be without sight. This is a very gradual process, possibly taking years to complete, and is not painful to the dog.

This loss of vision is not as dramatic as one might suppose, as dogs can cope surprisingly well with little or no sight - particularly in familiar surroundings. There is, however no cure for the condition and, where it occurs we need to look at preventing its occurrence. This is possible because there are two different levels of infection. The first covers those dogs which actually are going blind through the disease. These are described as affected animals and, quite simply, they should not be bred from.

The second category are those animals that carry the disease, and can pass it on to their progeny, but do not suffer sight loss themselves. They are described as 'carriers', and they can be detected by a specialist vet examining the eyes through and opthalmoscope (a magnifying 'torch'). Instead of a general 'withering of the blood vessels within the retina, they will see only small spots where the blood supply is compromised, but no progression is occurring. Such an animal can produce other carriers among some of its own offspring, but not necessarily all will be affected.

The danger comes when two 'carriers' are mated together. Any puppies, inheriting the faulty gene for PRA from both parents, will become affected and will lose their sight. They should not be bred from. Some others in the litter may simply inherit the 'carrier' status, and their sight may be unaffected but they should, again, not be bred from.

Identifying the 'carriers' requires any owners, thinking of breeding from their bitches or dogs, to have their eyes checked for the disease. It takes only a few minutes for a vet to check their dogs eyes, and does not require any anaesthetic - so is reasonably cheap. The dog will have drops put in its eyes first, to dilate the pupils and enable examination, but this does not hurt and is purely temporary. The last check I had done cost just under £70.

Very obviously stud dog owners should advertise their dog's status, i.e. PRA-clear, so brood bitch owners can use him on their bitches without worrying - and can advertise their progeny as from PRA-tested parents. If everybody does this the disease can be stopped in a generation.

We do not know how many animals currently carry the disease. There is even some debate as to whether the affected bitch has acquired Retinal Atrophy from some other external source entirely. Both she, and her sire, have shown no evidence in DNA sampling of any known strain of PRA. That does not mean that they cannot have some new, unidentified, mutant strain of the disease. Currently there are over 20 different variants which are specific to other individual breeds.

Her sire has been cleared of being a carrier on opthalmic examination and her dam, while not having been checked yet, remains visually active at the age of 14 years - so may be a carrier, but is not 'affected' with PRA herself. This differs from any other known strain, 'carrier' bitches, mated to 'clear' dogs (and vice versa), can pass on 'carrier' status but cannot produce 'affected' offspring.

The implications for the future

Our situation, within the breed, is that we have a single affected case of the disease in the UK. This is normally inherited but we have no concrete identification that this is the situation. According to all known, associated variants of the disease, the affected Brittany bitch must be the result of her parents being either two carriers, or one must be affected and the other a carrier. Neither of these scenarios fits the known facts. However both parents have produced other pups, which including grandchildren, nephews/nieces, etc, amounts to 70+ Brittanys in the UK. Wherever possible we have contacted puppy purchasers and advised them to have their pets checked and to report any 'carriers. Of course this ignores the fact that the parents of the one infected bitch would have inherited the disease themselves in the first place! Going back through their pedigrees implicates several hundred 'relatives' - and most of our best known kennel names!

The only way forward, is to screen any Brittany for PRA before breeding from it. Any that are tested positive for the disease should be reported to the Club's Dog Health Co-ordinator, and a register maintained - AND ALL INFECTED ANIMALS SHOULD BE NEUTERED.