Are mixed breeds genetically healthier than pure breeds?

[BCSnob]

In my recent reading of canine genetics articles I came across this gem. For some time know I have thought that for genetic diseases mixed breeds are just as prone to be affected as pure breeds since mixed breeds come from a mix of pure breeds. This article summarizes multi-breed genetic diseases and breed-specific genetic diseases.

Mark

We deal with genetic disease every day in our practice in
pure-bred, cross-bred and mixed-breed dogs. There is
a general misconception that mixed-breed dogs are
inherently free of genetic disease. This may be true for
the rare breed-related disorders, but the common genetic
diseases that are seen across all breeds are seen with the
same frequency in mixed-breed dogs.

**************************************************************

Breed-specific genetic diseases tend not to spill out into
the mixed-breed populations. Exceptions to this, however,
are ancient mutations that occurred before the separation
of breeds. These disease-causing genes mutated
so long ago that the mutation (and its
associated disease) is found in
evolutionary divergent breeds.

************************************************************

The most common hereditary diseases occur across all
pure-bred, mixed breed and designer-bred dogs. These
include cancer, eye disease, epilepsy, hip dysplasia,
hypothyroidism, heart disease, autoimmune disease,
allergies, patellar luxation and elbow dysplasia.

****************************************************************

The production of designer breeds — planned crosses
between two breeds to produce offspring — has become
a growing trend in commercial dog breeding. Puggles,
Yorkipoos, Cavishons and Labradoodles, to name a few, are
all coming into our clinics. Owners believe that these pets
will be genetically healthy because they are cross-bred. As
we treat these patients, we know that this is not the case.

Source: The Clinical Truths about Prue Breeds, Mixed Breeds, and Designer Breeds
Jerold Bell, DVM

[sher9570]

JRS & B wrote:
BCSnob - That's a long retort to just one word.

And thanks for pointing out to me that, Dog owners that want healthier pets will not get what they want without breeding healthier dogs. I would never been able to figure that out on my own without your help.

WOW....just WOW

Sher

[JRS___B]

BCSnob - That's a long retort to just one word.

And thanks for pointing out to me that, Dog owners that want healthier pets will not get what they want without breeding healthier dogs. I would never been able to figure that out on my own without your help.

[Sue_Bee]

Off topic, somewhat, but it irks me to no end that people go out and spend big money on "designer breed" dogs thinking that they are getting some sort of hybrid vigor, when many of the "breeders" of these dogs are starting with poor breeding stock, since many of these breeders, not all, but a good many of them, are just BYBs with no knowledge of good genetics, and are in it only to make a buck.

A person would be better off either getting a mutt from the city pound, or researching actual accepted pure breeds of dogs and finding a reputable breeder who knows what they are doing.

[BCSnob]

Not whatever,

Dealing with population genetics for a breed registry is something I do. It is very important to get the surveys correct, the sampling correct, and the math correct with the correct representation of the results disseminated to breeders so they can make appropriate and informed decisions about breeding genetically healthier dogs. Dog owners want healthier pets which they will not get without breeding genetically healthier dogs.

[JRS___B]

Whatever.

[BCSnob]

JRS & B wrote:
BCSnob - I never said anything about the the sample itself being adequate in size.

What I said was the sample was reasonably random and unbiased. Those are two absolute requirements for a valid sample, if you do not want to sample the entire universe of things you are analyzing.

You've totally missed the third requirement for a proper sampling of a population.

A very small sample has very wide confidence intervals; meaning you really don't have an estimate of the population with the small sample size. Stats indicate we are 95% confident the population rate is within within plus or minus 45 percentage points of your measured 40% rate.

In other words, based upon your 5 dog sample the population rate is between 95% and 0%.

[CatandJim]

Thanks Mark (BCSnob) for the scientific information. It is always nice to have your professional experience in science and research to help clarify certain topics.

As for me.... I've always had rescues, some mixed breeds and some "pure bred" dogs. Some have been healthy with amazing longevity and others, not so much. I just do the best I can to fall in love with the healthy ones... but that is tricky business since some of my favorite dogs have gone way too soon. Random and unbiased are my results, in more ways than one. :W

[JRS___B]

BCSnob - I never said anything about the the sample itself being adequate in size.

What I said was the sample was reasonably random and unbiased. Those are two absolute requirements for a valid sample, if you do not want to sample the entire universe of things you are analyzing.

I do like your moniker though. It fits you well.

[corgi-traveler]

Deb and Ed M wrote:


By crossing the two - did I lessen my chances of having a chemical-sensitive dog who's slightly less prone to patellar luxation?? Or am I whistling through the cemetery? 😉

Short answer, no.
Now if both parents were verified to be clear of those diseases, then yes. But you could also get an Aussie or a Poodle clear of those diseases with two non-carrier parents.

[Deb_and_Ed_M]

BCSnob wrote:
Deb,

You'll likley have an AussiePoo without chemical issues or patellar luxation. But is it a carrier of both diseases and how will you know?

What happens when you breed your healthy AussiePoo (possible carrier) to another healthy AussiePoo (possible carrier)? AussiePoos with bad knees and sensitive to chemicals or healthy AussiePoos?

It's not the affected dogs in the gene pool that are the real problem, it's the unseen carriers of the mutated genes.


Mark

Ahhh...(head smack) - good point! Which is why I insist on first-gen pups 😉 And why dear sweet Ben will be going in for a Lower Lobotomy in due time... 🙂

[CA_POPPY]

ie: off topic

[BCSnob]

Deb,

You'll likley have an AussiePoo without chemical issues or patellar luxation. But is it a carrier of both diseases and how will you know?

What happens when you breed your healthy AussiePoo (possible carrier) to another healthy AussiePoo (possible carrier)? AussiePoos with bad knees and sensitive to chemicals or healthy AussiePoos?

It's not the affected dogs in the gene pool that are the real problem, it's the unseen carriers of the mutated genes.


Mark

[BCSnob]

JRS & B wrote:
I agree my sample was small, but it was "reasonably" random and unbiased.

Go talk with your statistician friend about sampling a population with only 5 samples and how often this poorly represents the entire population.

[Deb_and_Ed_M]

But Mark - I'm going to use puppy Ben as an example:

Aussies have their problem with certain chemicals (somewhat herding-group specific)
Poodles have a high incidence of patellar luxation.

By crossing the two - did I lessen my chances of having a chemical-sensitive dog who's slightly less prone to patellar luxation?? Or am I whistling through the cemetery? 😉

[BCSnob]

JRS & B wrote:
Mathematically, an estimated incidence of possibly 15% is still 750% bigger than an estimated incidence of 2%.

Read the latter part of my last post. It has the most up to date genetic testing results (with a link to the source) which show 19% in the USA affected as compared to 12% affected in the UK/Ireland. Clearly, the inital estimate of 2% in the UK was a bit low compared to the more recent 12%.