PRA - where do we go from here?

Those of you  who were members six months agowill have previously have received full details of the new gene test for PRA in our breed, which was released by the American company OptiGen, earlier this year.  If anyone new dosn't know what I am talking about, feel free to ask!  By the end of this year, over 60 UK ACD's will have been gene tested fro PRA.  By adding these results to those known from the 1996 research and those that can be deduced from certain matings, we will know the PRA status of well over 100 ACDs in this country, past and present, which will give us an excellent basis from which to breed away from this condition.  This article will discuss some of the questions that have become apparent over the last few months.

Firstly, I know that some people are still having trouble with the results that are expected whent eh different PRA results are mated together.  Kimberly Jebson gives a helpful explanation of this in this newsletter.  To summarise again:

A = normal

B = carrier

C = affected

A x A = all A

C x C = all C

A x C = all B

A x B = 1/2 A, 1/2 B

C x B = 1/2 C, 1/2 B

B x B = 1/4 A, 1/2 B, 1/4 C

Perhaps the two most important points from the above are:

1. If either parent is a B, you cannot be sure what any particular puppy will be without a test.  If both parents are A and/or C, then you can be sure what all puppies will be, because they will all be the same as each other.

2.  The only way to be sure that no C puppies are born is to ensure that every mating contains an A parent.  This decision is not as straightforward as it may seem, for reasons I will come to later.

So far, our results have been roughly in the ratio 25% A, 50% B, 25% C.  This is very much what I expected, although, I know some people have been disappointed.  It is also very similar to the proportions found in the US, where the biggest number of dogs have been tested.  However, to have so few clear dogs certainly makes it more difficult to plan matings, and many people are uncertain how to proceed forwards.  I should point out that I have myself only bred only 1 ACD puppy in the past 13 years, so I am not having to make nay of these decisions myself, and I certainly do sympathise with those of you who are!

Firstly, and most importantly, let's not go overboard about PRA.  It's certainly a huge tragedy if a dog develops PRA, but in the ACD the signs are usually late and gradual, and the condition is generally painless.  A Pattern C dog is able to lead a perfectly normal life for much - if not all - of its lifespan, unlike a dog that is crippled with hip dysplasia or euthenized for biting people.  While I certainly believe that the prcd test is a wonderful tool that we should use tot he full, it is not the only thing we should consider when planning matings.  For example, Stella Smyth has a Pattern A dog, Morrow Red Coolibah, who is also severely overshot, of less than typical conformation, and castrated.  Stella is quite clear that Skippy is not of breeding quality.  He wasn't before he was known to be Pattern A, and he isn't know.  In contrast, Rokeglen Blue Mankara of Warrigal was the first bitch widely known in the UK to be affected.  Her descendents include many of the top winners in the ring today, and she has produced many progeny with wonderful temperaments.  I would consider her a prime example of a Pattern C bitch that was well worth breeding from, in spite of the prcd.  In two generations, we could have a Pattern A grandchild with Mankara's fine qualities.  So, let's all remember to look at the whole dog, and breed from dogs that are otherwise worthy, while trying to eliminate this particular problem gradually.

Does every dog need to be tested?  As you can see from the table above, there are some matings where it's possible to predict with certainty what the puppies will be.  I am not aware, luckily, of any CxC matings in the UK.  An example of an A x A mating would be when Drenoss Red Wyola was mated to Swordstone Ginny, back in 1989.  Both these parents were tested in 1996 and are known to be pattern A.  this litter, bred by Rose Fisher, must therefore all have been Pattern A.  My old bitch, Kingfisher Copper Red of Gilsland, is therefore an obligate Pattern A. that means that she must be Pattern A, because her parents are.  However, Copper is also a tested Pattern A, because she too participated in the 1996 study.  It's very useful to work out which dogs are Pattern A by virtue of their breeding, and as more and more matings occur between tested parents, this will become commoner.  But we must be careful to distinguish between tested dogs and obligate dogs, just so everyone is clear with what we're talking about.  It can be more difficult to remember that the A to C mating also produces predictable results - obligate B's.  A good example of this would be when Stella Smyth mated Warrigal Blue Todd of Chippinghey (a tested C) to Bryblue Diamond of Morrow (a tested A), producing a litter that included her Morrow Blue Aborigine, which we now know is an obligate B.  However, he hasn't actually been tested, so Stella could not say that OptiGen has stated he was a B, for example, even though we know he must be.

If people are producing litters where puppies could be of two or more patterns, they will need to decide whether to test some or all of the litter.  We don't yet know whether people will ten to test whole litters, or just the puppies they are particularly interested in.  Of course, this will partly depend on whether pet owners will want, or expect, puppies to be tested before purchase.  For a pet owner, the only real issue is whether their new puppy could possibly be a C.  It's important to realise that an A and a B are IDENTICAL, UNLESS you are planning to breed from them.  A carrier will never develop prcd during its life, any more than a normal dog will.  So we all need to be sure that puppy buyers realise that a B puppy will make just as good a pet as an A.  The only reason for preferring an A is if you was to breed from it.

Anyone who is concerned how few A dogs we have is right toworry.  However, things could be very much worse.  When you study pedigrees of UK ACDs, no dog has had more influence on the breed in this country than Drenoss Red Wyola, and we are extremely fortunate that he was a Pattern A.  If he had been even a B, I think our PRA situation would be far worse than it is, because well over half the dogs in the country today are descended from him.  I think (certainly those in the show population).  At lease we do have several A dogs to choose from, and they are from a few different bloodlines.

However, as far as I can see, there are only 5 tested A entire male dogs in the UK at the moment, and slightly fewer bitches of breeding age.  Of course the situation is not quite that bad; there are other untested obligate As that I haven't included, and many more dogs and bitches that have a good chance of being As.  But which ever way you look at it, there aren't very many.  So what do we do?  As I stated earlier, the only way to be sure that you don't produce a C puppy is to make sure that every mating includes at least one A parent.  In this newsletter, Kimberly Jebson explains how she came to the decision that she did not, herself, want to risk producing Cs, and therefore will be planning matings carefully to avoid this.  Kimberly has obviously thought about this very carefully, and has made a very sensible decision, which nobody could fault.  However, there is another way of looking at it.

If all matings include an A parent, then the quarter of the dogs that are A are going to be hugely over-represented in the next generation.  More particularly, many of these dogs are closely related, and so certain dogs could come to have a massive influence on future generations.  For example, Garreg Ddu Aphrodite is a parent or grandparent of 6 out of the 10 new Pattern As from the last clinic (and one of the other four is castrated, remember!)  Aphrodite is a very nice bitch, and I am in no way doing her down, but we know from other breeds that to concentrate excessively on one bloodline can lead to problems later on.  For example, in Portuguese Water Dogs in the US, there was a known problem with an inherited metabolic condition called storage disease, that was common in one line of the breed.  To breed away from this problem, everyone turned to the other main line, and as a result the breed developed a problem with PRA, which had been lurking in the second bloodline.  A similar situation occurred with Basenjis; they used to have a big problem with an inherited condition called haemolytic anaemia.  A test was developed which enabled breeders in the US to avoid all dogs affected with, or carriers of HA - and they did.  They used the relatively few dogs that were HA free.  A few years later, it became apparent that the HA free bloodlines had PRA and/or a kidney disorder called Fanconi Syndrome, and those two diseases, previously quite rare, were now a huge problem.  American Basenji breeders had to go back to the African bus to get healthy  outcrosses.  We can learn from these examples, and try to avoid jumping from the frying pan into the fire by keeping as many different bloodlines as possible.

All registered ACDs worldwide go back to a handful of dogs in the 1950's.  We already have very limited genetic diversity, therefore, that makes it all the more important to conserve what we have.  There are various tools available to do this, and I know that many breeders are already using them.  In Particular:

a.  We need to use as many different A dogs and bitches as we can (providing that they are otherwise sound), particularly those that come from less common bloodlines.  We also need to breed from otherwise good B and C dogs and bitches, again, particularly if they come from less common bloodlines.

b.  We can obtain new blood from tested dogs overseas, either by AI or by importing actual dogs.  Unfortunately none of the dogs that have recently been imported have turned out to be As, but several of them have already produced A children that can be bred on from, which will be very useful for the breed.

One particularly thorny issue is whether to carry out B to B matings.  Such a mating can produce A or C progeny, or Bs like the parents.  Therefore, a B to B mating is a way of salvaging an A from a bloodline that may not have any at the moment - but at the price of possibly producing affected puppies.  Remember that the ratios for different types of progeny are estimates, not guarantees - so a litter of eight puppies from a B to B mating could have 2 As, 4 Bs, and 2 Cs, as predicted on paper, or four or five As (if you were lucky) or four or five Cs (if you were unlucky).  Anyone who wanted to breed B to B should plan how they will cope with any C puppies.  Some breeders overseas are culling such puppies at birth; some are testing and neutering them; some are informing puppy buyers of the risks and letting them make their own decisions (interestingly, many people choose not to find out if their new puppy is a C, apparently.)  Given these choices, many people, like Kimberly, may decide that they would rather not produce any Cs.  However, there might be a case when somebody wanted to mate two excellent Bs, perhaps of rarer bloodlines, in the hope of obtaining an A that they could then breed on from.  I honestly don't know what I would do if I were in this position, but I do think that this is a complicated situation, and that there may not be any single right answer.  We are unlikely to all agree about B to B matings, although I certainly hope and believe that nobody would deliberately mate B to C or C to C.

So far, everyone has worked together in a very positive way, and as a result we now have this wonderful test.  I really hope that we all continue to co-operate, even if people don't always agree about ethical decisions.  If we use this tool carefully and wisely, then in ten or fifteen years time we could have a population almost free of PRA, while preserving all the other qualities our breed has at the moment.  That's what we should be aiming towards.  It will be very interesting to compare the percentages of As, Bs and Cs in five years' time with those we have today.  I wonder what we will have achieved?

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