Genetic Testing by Breeders - Value and Limitations

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Posted On : 15-07-2015

If you're on the hunt for a good breeder for your next puppy, and haven't been living under a rock, you are probably aware of the considerable risk of genetic illness faced by owners of purebreds.  Undoubtedly it is a big problem, and its getting worse. And its  not just affected dogs that suffer  but also, of course, their owners - emotionally and financially.  So what can you do to reduce your risk?

Some breeders "do the right thing" and have their parent dogs genetically tested for heritable defects.  These tests only need to be done once and are good for the life of the dog.  So if a breeder has such tests available for the parents of that puppy you have your eye on, you should be good to go, right?  Unfortunately no!

Here's why: there are so few genetic tests currently available.  Fact is, there are simply no tests in existence yet for most of the potential inherited illnesses that plague purebred (and inbred designer crossbreed) dogs.

Take PRA (Progressive Retinal Atrophy) as an example.  This is a disease known to lurk in the gene pool of several breeds, among them the one I breed - Miniature Schnauzers.  However, the actual gene(s) responsible (and yes, for many ailments it is not a single gene involved, but a combination) are different from one breed to the next.   Identification of the gene(s) in each breed for each heritable illness is a necessary prerequisite to being able to screen for it with genetic testing.  Which leaves us - at the moment - with no tests for most such diseases in most breeds.

So what can you do?

One option is to forget purebreds altogether and go for a cross breed or designer dog.  Not a bad idea but it has its downside too.  For a start, the dog you end up with from a cross is a lot less predictable than with a purebred puppy in all respects - energy level, temperament and size.  Secondly, some of the designer dogs are just as inbred as many purebreds and therefore at equivalent risk.  Thirdly, some of the designer dogs are produced from crossing breeds that are related and thus share many of the same genes - e.g. poodles and miniature schnauzers - thereby largely negating some of the health advantages to going for a crossbreed.   But if you keep these things in mind, even though mongrels are not 100% immune from suffering genetic illness, this option can at least reduce the risk dramatically.

The other alternative - especially if you have your heart set on a purebred - is to go for a non-inbred puppy - that is, one that comes from two unrelated parents.  Of course, if it is a purebred then its parents will be more closely related to each other than to dogs of a different breed, but their pedigree papers should at least show no ancestors in common for a minimum of 4 generations.  This will significantly reduce the risk of all genetic illnesses and enhance your puppy's chances of living a long, healthy life.

If having a healthy dog was a high priority, I would also avoid rare breeds (very limited genetic pool) and those with the inbuilt design flaws that keep vets busy - like squashed faces, skin rolls, long pendulous ears, and short wonky legs.  I would also avoid very large breeds - they have shorter lives and are more prone to bone cancer and joint problems.

You can also increase your potential of a great health outcome for your puppy by also going for a breeder who has clinical examination tests conducted on her parent dogs.  This is common for problems that are readily detected by direct observation - for example looking at the retina of dogs over two years old to detect signs of PRA - or x-rays such as for hip dysplasia.  However, just because parent dogs are not clinically affected by heritable diseases does not rule out the possibility that they may be symptom-free carriers of such diseases.  So it is still possible for two clinically unaffected parent dogs to produce affected puppies.

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