DNA screening : prcd-PRA

The second of the recommended checks is a DNA test for prcd-PRA. PRA (Progressive Retinal Atrophy) refers to a group of diseases that  causes cells in the retina at the back of the eye to degenerate and die, even though the cells seem to  develop normally early in life. "prcd" stands for progressive rod-cone degeneration, a type of PRA. The rod cells operate in low light levels and are the first to lose normal function. Night blindness results. Then the “cone” cells gradually lose their normal function in full light situations. Most affected dogs will eventually be blind. At the moment there is no treatment, or cure, for PRA.

While the eye certificate scheme checks for PRA, it does not tell you whether or not the dog carries a mutant copy of the PRCD gene. Two dogs could be mated that both pass their eye certificate but then had puppies that were PRA affected.  The cause of this was that both dogs were carriers of the gene, so while neither was affected, because they both carried a mutant gene, some of the puppies ended up with both and therefore were affected.

I could not imagine anything more horrible than your dog going blind and with this test being well established and recommended by the Kennel Club, it was a no brainer for me.  If both parents are tested as being clear (neither carries a mutant gene) then all the puppies will be clear by parentage and will never delevlop prcd-PRA.  The DNA tests show the dog as being either Clear/Normal, Carrier (one copy of the mutant gene) or Affected (both copies mutant). The disease is inherited as a recessive trait (a mutant gene must be inherited from each parent to cause the disease in the offspring. Possible matings are :

Clear x Clear = 100% clear offspring
Clear x Carrier = 50% clear, 50% carriers
Carrier x Carrier = 25% clear, 25% affected, 50% carriers
Carrier x Affected = 50% carriers, 50% affected
Affected x Affected =  100% affected
Affected x Clear = 100% carriers

So, it is perfectly acceptable to mate a carrier to a clear, this combination still ensures that all offspring will never develop prcd-PRA (they may be carriers though so would need to be tested before breeding from). Even a mating between an affected and a clear will never produce any affected pups - but they all will be carriers. Once these carriers subsequently mate with a clear, you are half the way there to eradicating any signs of the disease from the line - which shows 1/ How important testing is and 2/ How an affected or carrier status does not mean that the dog can't be bred from.

I used a company in the US (http://www.optigen.com/opt9_test_prcd_pra.html) to do the test, going through a UK 20/20 clinic that organise the posting of the blood samples and give you a 25% discount on the price. I've also used this place in the UK for other DNA tests and they do the test as well (http://www.laboklin.co.uk/laboklin/showGeneticTest.jsp?testID=8094). I didn't know about this place at the time and definitely would have used them if I had known. You get your vet to collect a blood sample and send it off. I got Moy vets to take the sample while I was there getting the hips and elbow x-rays.

Costs = £95 test, £9 20/20 clinc, £7 postage, total £111

The results of the tests are recorded on the Kennel Club database.

As of today, I'm still waiting to hear back the results of Jess' test. Her father was clear and her mum was either clear or a carrier so jess will either be a clear or a carrier.