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sandgrubber

The downside of DNA testing

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The sick puppy thread has been going off track.  Though I'd move a bit of the discussion to the health thread. 

DNA testing has its good side, but it worries me, especially as breeders are increasingly being held liable for breeding dogs with genetic defects.  Take exercise induced collapse in Labradors.  A simple recessive gene.  Not the worst of diseases by a long shot... many affected dogs never show symptoms.  It's estimated that 39% of Labs carry the gene... mostly as a single copy.  Everyone wants to say their pups are clear of genetic diseases.  So do we take a big chunk out of the breeding pool to get rid of it? Is that wise, given that a large number of dogs have already been removed from breeding because they are PRA carriers.  

And what comes next?  Maybe some undesirable coat and eye color genes? Or genes that may result in a higher risk of some cancer or some form of epilepsy. 

If you drop 30% and then drop 30% of the remainder, you end up with less than half of the original breeding pool.  And do it again and you're down to 34%.   It gets scary. 

 

 

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Dogsfevr   

In a breed I’m involved with breeders are very savvy to using DNA results as a tool but not as the end of the world scenario.

the complete package needs to be considered .

For example PRA is late onset meaning 10 plus years .

Breeders will breed carriers to clear ,affected to clear providing the rest of the package ticks the boxes such as hips/elbows/nature .

Going blind in old age can happen anyway ,crappy hips at a young age affects it for ever ,risks that need to be prioritised ,managed but still with the future in mind 

 

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Scratch   

The idea of DNA testing is fine. It’s the response to the results that becomes the issue. 

A problem is found, but instead of looking outward into a vast pool  of available material (every domestic dog on earth) for a solution, pure breed pedigree breeding by its very nature, looks inwards to an ever diminishing, narrow limited pool ( dogs of the same breed) for the solution. There becomes a point where the pool is so shallow and full of contaminates that it’s beyond salvage unless fresh material is sourced to top it up with. Yes, even that fresh material may be contaminated, but it’s really the only hope of keeping the pool at a sustainable level. 

DNA could equally be used as a powerful tool in discovering ways to replenish gene pools. 

I used to have my feet planted firmly over in the pure breed pedigree world. But as I’ve gotten older, and hopefully wiser, I’ve come to despair of what I once held in high regard. The gravity of the inherent problem of the idea of purity. 

 

 

Edited by Scratch
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Scratch   
10 hours ago, Papillon Kisses said:

https://www.facebook.com/327283277934/posts/10156917887667935?s=100000493700819&v=e&sfns=mo

 

Some really good discussion in this episode of Drinking from the Toilet. They get into more than just behaviour.

That’s thought provoking. Unfortunately in relation to pedigree pure breed dogs, if the heart disease is found in the breed, ‘breeding away from that’ is limited to looking within the same breed, a massive restriction to work with. 

Eta...I only listened to the short grab on the FB page.....now listening to the whole podcast..

 

 

Edited by Scratch
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Just passing by, but this came out this past week and covers much the same of breeders potentially overculling (by way of neutering) dogs for assorted reasons (colour, eye shape, genetics of assorted levels) that might otherwise help keep the gene pool flexible. 

 

https://www.frontiersin.org/articles/10.3389/fvets.2019.00241/full?fbclid=IwAR1c97kFeUc-hAWes-6w2RY2fYkcLcu3NNJ6VNytrO_wR3mMCvda89AvrZs

Edited by Two Best Dogs!
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Diva   
On 23/07/2019 at 5:05 PM, sandgrubber said:

 

DNA testing has its good side, but it worries me, especially as breeders are increasingly being held liable for breeding dogs with genetic defects.  Take exercise induced collapse in Labradors.  A simple recessive gene.  Not the worst of diseases by a long shot... many affected dogs never show symptoms.  It's estimated that 39% of Labs carry the gene... mostly as a single copy.  Everyone wants to say their pups are clear of genetic diseases.  So do we take a big chunk out of the breeding pool to get rid of it? Is that wise, given that a large number of dogs have already been removed from breeding because they are PRA carriers.  

And what comes next?  Maybe some undesirable coat and eye color genes? Or genes that may result in a higher risk of some cancer or some form of epilepsy. 

If you drop 30% and then drop 30% of the remainder, you end up with less than half of the original breeding pool.  And do it again and you're down to 34%.   It gets scary. 

 

 

There is only one DNA health test in my breed. A simple autosomal recessive. Some breeders still deny it is meaningful, and a few want to eliminate all carriers from breeding.

But the majority within those two extremes follow the ‘one parent clear’ rule. Carriers are still bred from, and I don’t think we have done much damage to the gene pool because of the test. When someone tried to start an international campaign not to breed from carriers she got reasonably polite explanations of the risks of that, and no real traction.   Understanding of genetic diversity is also increasing, and we have a breed diversity study underway with UC Davis. I think that is harder for people to get their head around, but a good evidence base is a good start. At this stage we don’t really know how much of a problem we might have. 

I guess I am just a lot more optimistic that the breed community can respond. As long as enough breeding continues. The pressures on breeders are probably the biggest risk to the health of the breed. 

 

 

Edited by Diva
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