can anyone please explain the procedure of the annual eye test which concludes this outcome
Two parents tested annualy and tested uneffected for mrd/gpra/cpra so,
mated together as we want to be sure we are mating clear tested dogs
So how come that one of this litter is affected? will others in litter be affected?
WHAT is the point of having these eye tests done and thinking both dogs to mate are ok and how can we tell what the outcome of puppies born to clear parents are going to be
I dont understand what we are suppose to do
Can anyone explain and make it clear to me cause i am baffled

Quite honestly I am getting fed up with it. I litter screen my pups and so far have had all clears. However, at my boys first eye test, the specialist said 'have I seen him before' I said no, but he was litter screened clear. Now, normally this would get a response of 'great that's the right way to do it' or something similar. However, this time it was 'well we are now finding a late onset MRD'. So I said, 'so what you are saying is that it is not worth dragging my six week old puppies for miles , wetting and being sick as it isn't worth anything'. The answer, 'well basically yes, but don't say that I said that'.
I have always believed that I do as much as I possibly can to follow any guidelines to breed from healthy stock, but I hate it when they keep moving the goalpost. BTW my boy did pass.
The other thing about MRD is that it can come and go. I know of someone who's bitch had MRD and was mated with all the puppies being litter screened clear. She has since been eye tested clear herself!!!!

Basically, the answer to your question is.... there isn't an answer.

Clinical eye tests only tell you the clinical eye status of the dog concerned  they can't tell you if the dog or bitch is carrying a recessive gene for an eye disease. However this is as much as we can do until genetic tests are developed for the disease that affect each breed.

MRD is inherited via an single autosomal recessive gene that the puppy inherits from it's parents, carriers are clinical Normal as are unaffected dogs. This link is for the PFK DNA test but the mode of inheritance is the same as for MRD(unless the MRD has been acquired & caused by an infection)

You might want to contact Bryan McLaughlin @ the AHT bryan.mclaughlin@aht.org.uk & enquiry about DNA samples from the whole litter & the parents & G parents(if available)

The eye test is a clinical examination.  It can only tell you that a dog is clinically affected/unaffected by a disease at the time of the test.

It cannot show if the dog is a Carrier.

Most eye diseases have a recessive mode of inheritance, meaning they have to inherit a faulty gene from both parents to be affected, those that inherit just one copy will be carriers but clinically clear, and those that inherit clear copies of the gene will be unaffected.

So if affected offspring have been produced for a recessive condition by two clear parents, this means that both are Carriers (having one copy each of the faulty gene)

The probability with such a mating is that 1/4 will be affected, 1/4 clear and half carriers.

This Optigen page on PRA explains it quite well and also gives a chart.

http://www.optigen.com/opt9_test_prcd_pra.html

what i cant grasp is -ie if the bitch is a carrier but mrd tested unaffectedhow can the owner know that the dog she is going to mate her to is also a carrier if he to is tested unaffected
there is no dna test  for mrd as yet so where do we go?

You can't, you can only do your best with what science and study have to offer.

In other words research pedigrees, avoiding doubling up on dogs that have produced etc.

We have had the same in my breed, mostly avoided PRA, but had four cases in the time I have been in the breed.

With the latest case a few years ago it was decided to send samples off from her and relatives and any that were related to the earlier cases.  Dr Acland in the USA was able to compare the samples to the genes that already had been found for various forms of PRA and found that ours was the prcd-PRA, and we have had a DNA test since October.

There will always be health issues to look out for, some have complex or unknown modes of inheritance, some have clinical tests (but these as you have found are limited) and luckily for some that have a simple mode of inheritacne we now have DNA tests.