Lesson 101: Breeding American Bulldogs for Health

Discussion in 'Health Tests and Genetic Diseases' started by Igor, Jan 13, 2018.

  1. Igor

    Igor Administrator Staff Member

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    So there was a deeply insightful and wonderfully naive question that got posed. This is probably a very typical mindset of people with no breeding experience. This also explains why there is a wholly unjustified stigma against ABs that are ICH carriers. Note we have never spoken ill of a dog just because it is an ICH carrier. That'd be ridiculous - read on to see why. We simply require that people test to know whether they are for any litter ads. So here we are with our ongoing breeding education!

    Q. "Why would you breed a dog that is an ICH carrier if there are ICH clear dogs out there?"

    Background: There are very few genetic disease tests available for the American Bulldog breed. Namely ICH and NCL. Both are horrible diseases. If two carriers are bred, then a portion of the pups in the litter will have the actual genetic disease. A carrier in itself is a fully healthy dog as it concerns the disease for which it is a carrier.

    Dog DNA is vast and complex, with countless thousands such traits/diseases being programmed into the DNA.
    We have tests available for a whopping TWO out of that total number.
    As you are aware, half the DNA is inherited from the dad and half from the mom.

    So, consider a hypothetical:

    There are two breeding candidates that are IDENTICAL from what the eye can see. Even identical personality, temperament, etc.

    Candidate A: ICH clear
    Candidate B: ICH carrier

    From this limited information, A is better. After all they look the same.

    But then, consider the vast number of genetic diseases out there for which we DO NOT have DNA tests. For simplicity's sake, this is not scientific because a plethora of diseases are not simply passed down as an autosomal recessive trait - just two alleles - either of which can be positive or negative for the disease. Both have to be positive for the dog to actually have the disease. Also, I'm limiting the number of genetic diseases simply for effect. The real list would include thousands of such traits.

    So, if we knew the real genetics of both dogs, what if it looked like this:

    Candidate A:
    ICH - clear
    Epilepsy - afflicted (the dog died at 4 years old from epilepsy after you bred him/her)
    Heart disease - carrier
    Cancer - carrier
    Weak ligaments - afflicted (the dog tore both ligaments but the breeder did surgery that went perfect and never told you)
    Hip Dysplasia - carrier
    Weak temperament - carrier

    Candidate B:
    ICH - carrier
    Epilepsy - clear
    Heart disease - clear
    Cancer - clear
    Weak ligaments - clear
    Hip Dysplasia - clear
    Weak Temperament - clear

    As you can see, A is a horrible dog to breed and B is actually squeaky clean when it comes to its genetics.
    THIS is what real breeders do. They don't have the magic wand to wave to find out all of this information. Through a multitude of generations of breeding their own lines of dogs, they figure out the hidden genetics of their dogs through deduction.

    Take the simple example of ICH as a disease. When there was no DNA test available for American Bulldog Ichthyosis, a savvy breeder would figure out that two dogs they bred are both carriers when they get a litter with some pups afflicted with the disease. Voila! Now they know. Without any DNA testing.
    THIS is why breeding correct healthy dogs takes an immense amount of dedication over decades. No way you will have enough insight into this stuff after breeding for even 5 to 10 years. Each new generation continues to add new insight concerning the genetics of dogs you bred even 10 years ago.

    You need your own dogs to live out their full lives and see how long they lived, what they were afflicted with, and so much more. This is also why it's critical that breeders maintain contact with as many of their owners as possible throughout the lives of their dogs. The more complete and bigger the sample size of the dogs you have produced, the more you will know. This is only possible over many years of breeding YOUR OWN productions. If you constantly breed to other breeders' dogs you will always have very limited info. You need to know the pedigree of both sides of the breeding. You need intimate familiarity of the many generations of dogs that are behind the dog in question.

    In the real world and not an extreme hypothetical above, the decisions that breeders make are a lot simpler. They just don't breed two carriers of ICH and NCL. Like they wouldn't breed two dogs that they know are asymptomatic carriers for anything else they've figured out through deduction.

    No two dogs are identical. If the breeder objectively evaluates an ICH carrier as a better dog than an ICH clear dog, and the dog they're breeding to is ICH clear, then that's the end of it. Breed them and test all the pups in the litter that may get bred in the future for ICH to find out whether they're a carrier or a clear. Keep it simple.


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