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Why? are ilnesses bred out, i.e crossbreeds

Discussion in 'Dog Chat' started by haeveymolly, Jul 12, 2009.


  1. haeveymolly

    haeveymolly PetForums VIP

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    We were having a discussion about crossbreeds being healthier or hardier than purebreeds, why are genetic ilnesses bred out, what ime trying to say is why dont the genetic/breed related ilnesses of each breed in a dog with multiple breeds why doesnt the dog be more at risk from having the ilnesses common to each breed. ime finding it hard to explain, ime just curious as to why.:confused:
     
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  2. Blitz

    Blitz PetForums VIP

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    They are more likely to inherit more problems. But I suppose only have half the chance. A straight cross between 2 breeds would have a good chance of inheriting problems from either parent but as they dilute the problems will become less likely to be passed on. So if you have a Lab cross GSD you probably have as much chance of hip dysplasia as if they were pure of either breed but then if you cross that cross with a breed or crossbreed that isnt likely to suffer from hip dysplasia then there is less percentage chance that the pups will suffer from it. Always supposing that the original parents carry the gene for it of course.
     
  3. sequeena

    sequeena PetForums VIP

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    I would say it could go either way. The dog could either get all the illnesses or none at all, it's the luck of the draw.

    I have noticed that all the crosses I've had lived for longer than the purebreds I've had though :confused:
     
  4. haeveymolly

    haeveymolly PetForums VIP

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    Yes ive always been told they usually live longer and ive also heard that they have less chance of inheriited ilnesses ime now wondering if its true after reading the last 2 replies, ime even more confused.:rolleyes:
     
  5. Badger's Mum

    Badger's Mum PetForums VIP

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    So am i;), best stick to springer's:D
     
  6. Blitz

    Blitz PetForums VIP

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    Genetics is confusing! I am no expert but basically some genes are recessive and some are dominant. If dominant then receiving the gene from one parent would give the pup the liklihood of inheriting whatever the gene is for. If recessive then it has to receive the gene from both parents. I know some coat colour genetics but not inherited illnesses etc but obviously if (for eg) hip displaysia gene is dominant then one parent can pass it on. If it is recessive (which I dont think it is ) then it would need both parents to pass it on. I might be talking rubbish here but on the assumption that some inherited problems are caused by a recessive gene then if you cross 2 breeds, one of which never carries the gene then the pups could never get the problem - but some of them would still carry the gene so if they were then mated with another dog that carried the gene they could then pass it on to their pups. Very simplified and I am sure someone else will actually know which problems are caused by dominant or recessive genes but it does give you an idea how an inherited problem could become impossible for a mongrel to inherit at some point.
    As for living longer, well I suppose if they have less chance of inheriting common breed specific problems then the healthy ones are likely to live longer. But then again not every purebred dog suffers with breed specific problems. Your good old mongrels were traditionally lab/collie/terrier type crosses, all of which are long lived breeds anyway, so that could have something to do with it.
     
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  7. haeveymolly

    haeveymolly PetForums VIP

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    Yes that sort of makes sense, it is confusing though.
    Dont know why i think of these things and the need to know, ile have to just start excepting that thing are as they are:D:D

    What i an wondering now is we have purebred springers and our eldest was the younger brother of the 1st one we had and lost last year due to a genetic disease but harvey our eldest one has not got it so maybe the gene was not ressesive is that the right way round?. oh god but thanks for this reply, its enlightened me a lot.
     
  8. Sleeping_Lion

    Sleeping_Lion Banned

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    It is a bit of a myth that cross breeds are hardier, although it does seem that heinz 57's go on forever, it's referred to as 'hybrid vigour'. As already said, it can go either way, you might get a dog that inherits problems from all the breeds in it's genetic make-up, there's no guarantees. I'm easily confused by all the recessive genetic malarky, but where you've got an illness common in both dogs, which a lot of hereditary illnesses are common, there's the chance it will be passed on. My last rescue, Chloe, was a Lab/collie cross, she had bad joints, cataracts, and a deformed soft palette, as well as the occasional bit of a dodgy disposition, certainly not the healthiest of animals.
     
  9. haeveymolly

    haeveymolly PetForums VIP

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    You would think that a first cross dog would have 2 chances of herediting a disease and the 57's would have lots of chances of getting the genetis ilnesses of each breed in it. Or is that too simple:D
     
  10. Johnderondon

    Johnderondon PetForums VIP

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    It's not a myth. Mixed breeds and crossbreeds live longer because their genes embody a greater degree of diveristy.

    It's not a good idea to have babies with our relatives. It's so well accepted in humans that the principle is enshrined in law but with our dogs.....



    (source: Breed Data Summary )
     
  11. gesic

    gesic PetForums VIP

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    Another way to look at it is;
    a stray or roaming dog who is fit n agile able to travel miles go over and under obsticals to get to an in season bitch has got to have excellent genes!
    In all honesty crossbreeds are as likely to get hereditory disease as any other.
    Most purebred breeders spend a lot of time and money researching and choosing a match that not only has the breed charecteristic but also free of hereditory disease. The sd fact is that many hereditory diseases occur late in life and by that time the dog/bitch may have already been used.
    There is an element of luck in dog breeding and also remember that more research and historical evidence is available with ped dogs.
     
  12. Sleeping_Lion

    Sleeping_Lion Banned

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    Now you're asking!! Past the limitations of my experience I'll happily admit, my small amount of knowledge is with Labs. You'll have to have a read up, there's a few websites that have papers accessible for people to read, I regularly get updates by email about breaking news in the veterinary world, most of it isn't particularly interesting, but sometimes you get some good articles. There was one recently about 'growing' new hip joints for dogs, which wil be a huge breakthrough, although sad that we need it in the first place.

    The other thing is, as I've posted a few times about health testing in general, if you have a dog that is tested and comes back as affected for a genetic disease, it doesn't mean that your dog will necessarily develop that disease within the span of its own lifetime.
     
  13. Johnderondon

    Johnderondon PetForums VIP

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    Think of it this way.

    The same gene comes in different versions (called alleles). Each of us has two versions of each genes, one inherited from each parent.

    Now, for example, say one parent passes on a gene for metabolising vitamin A that is broken. It won't matter so long as the offspring has a working version from the other parent. It will still be able to metabolise Vitamin A. But, obviously, if both parents pass on a defective gene then the offspring will suffer whatever diseases and maladies that Vit. A fends off.

    So, in any population there are carriers (1 gene) of defective genes, and a smaller number of affected (2 gene) animals.

    The real problems start if we isolate a breeding population because then, with each succesive generation the number of carriers (and hence the number of affected) will rise until we get to a situation where the population is saturated with defective genes. This has happened over and over but, as an example, take dalamations who all - every single one - have a defective gene that causes bladder stones.

    Doubtless that GSDs have a high incidence of ome other deleterious gene but it won't be the same gene as the Dallies so a cross between the two will produce dogs that have only one version of the bad dallie genes and so wont get the bladder stones and one version of the bad GSD genes and so won't get those ailments either.

    This is hugely simplified but that's the principle. Mixed and cross breeds can suffer like the pure breds but the incidence rate is lower.
     
  14. Johnderondon

    Johnderondon PetForums VIP

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    That's not right.

    Crossbreeds have the potential to get as many inhertitable diseases but their likeihood is less.
     
  15. gesic

    gesic PetForums VIP

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    Would that not depend on the x?
    Like I said in my first post a dog fit to travel to a bitch is likelyto have excellent genes as far as physical confirmation goes, But mans intervention and the cross may not be as fit as man would think.
    I do understand u are trying to say the more u dillute the gene pool the less likely the hereditory defects are to appear in the resulting offspring BUT this depends on dominent and recessive genes and what they are partnered with.
     
  16. haeveymolly

    haeveymolly PetForums VIP

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    I understand what you are saying in your last paragraph, going off thread a little when i say this is another grey area if you like in health testing, going back to our eldest springer and his brother we lost last year at 8 yrs he parents were health tested and no issues so they bred twice with them the ilness shows at around 5 yrs to 6 yrs we never intended to breed but could have done before the signs of the ilness we would have then potentially bred the ilness into the pups, then one of them pups could have been bred with and when i think of the potential problems we could have caused, just glad we havnt had it to go through with our eldest now who was montys brother.
     
  17. Johnderondon

    Johnderondon PetForums VIP

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    Oh, for sure.

    There is a statistical possibility of poor health in any individual and there's is the risk of outbreeding depression if the cross is too diverse. As a (ridiculous) example we could cross a labrador with a hyena and end up with progeny that could not survive in either Kenya or Kent.

    But, as a rule of thumb, cross and mixed breds will enjoy better health and longer life than their purebred cousins.
     
  18. haeveymolly

    haeveymolly PetForums VIP

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    This subject is very interesting but equally as confusing. Thanks to everyone that has inlightened me ive only ever has 1 crossbreed and only for a short while my other 3 have all been purebreds so have nothing to compare with, its just what ive heard people say for years that mix breeds are less likely to have genetic diseases.

    Its a minefield really isnt it?
    When monty became ill i did lots of research as the illness was difficult to accept and deal with and the ilness was more typical to other breeds not springers, thats where luck of the draw comes in unfortunatly.
     
  19. Johnderondon

    Johnderondon PetForums VIP

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    It gets worse, haeveymolly, because some genes that cause disease when paired with another identical version can protect against disease when paired with a different version. The gene which causes sicklecell anemia in humans when two copies are inherited also protects against malaria when only one copy is inherited.


    It's mind-numbingly complex. Sometimes, when I think about it, my brain runs out my ears.
     
  20. haeveymolly

    haeveymolly PetForums VIP

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    LOL! so true never heard it put like that though
     
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