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Posts Tagged ‘Inbreeding in Dogs’

This scene should be part of a population management program for golden retrievers. Source for image.

This scene should be part of a population management program for golden retrievers. Source for image.

Let’s clear the air a bit.

When a dog breed is put into a closed registry system, it has been decided to create a population of animals that has a population genetics structure that resembles that of an endangered species. There is plenty of evidence that many very popular breeds have terrible genetic structures. In a 2008 paper in the journal Genetics, Calboli et al. performed an analysis of ten dog breeds in the UK, using Kennel Club pedigrees to determine effective population size. Effective population size tells you how big the population would be if a random number of individuals were put together that would have the same amount of genetic diversity as the population in question. The general rule for conservation genetics is that anything under 100 individuals is of critical concern.

The results went as follows:

Akita – 45 (effective population).
Boxer – 45
Bulldog – 48
Chow Chow – 50
Rough Collie – 33
Golden Retriever – 67
Greyhound – 17
German Shepherd – 76
Labrador – 114
English Springer Spaniel – 72

Shocking, eh?

Every one of these breeds is a closed registry breed.

All but one have very real problems with genetic diversity. Only the Labrador retriever is out of the crisis zone– and just barely.

If you read the paper, the golden retriever, which doesn’t look as bad, has the worst problems with popular sire effects in its population. Only 5% of the male dogs in the UK population are sires, and for a popular breed, this is a recipe for disaster.

This is because even though these dog breeds have a genetic structure resembling that of an endangered species, they are not bred the way conservationists would breed endangered species.

With endangered species, the goal is to conserve as much genetic diversity as possible.  The Chinese spend countless hours working to maintain what genetic diversity can be spared in giant pandas. Giant pandas, which are actually a primitive bear with no living close relatives left, have no populations for which there can be outcrosses.

You can’t say that about golden retrievers, which would be greatly served with occasional outcrosses to their somewhat more genetically diverse smooth-coated cousins. The differences between Labrador and golden retrievers aren’t that extreme. Both are derived from the same root stock. Both breeds share ancestors in documented pedigrees, and there was a famous cross between a yellow Labrador (Haylers Defender) to the Haulstone line of golden retrievers in the 1920’s.

Not ancient history at all!

If we had a dog culture that was based upon reason and science, this would be a no-brainer.

However, this is not the dog culture we have.

The dog culture we have does two things that utterly gum up the works when it comes to sound population management principles:

1. Closed registries as dogma.

2. Competitive dog breeding.

The former is what creates the genetically compromised population. The latter is what exacerbates it.

Could you imagine the madness that it would be to breed giant pandas based upon a conformation standard?

But that’s exactly what is happening in the world of dogs, and as I’ve noted before, it’s not just dog shows that are causing this problem.  Breeding choices that are based solely on trial performance do the exact same job.

Each generation of dogs that is bred under these conditions loses genes. Some of these genes might be pretty nice to have– like the gene that Dalmatians had for producing urine with normal levels of uric acid. This was actually lost to the entire population of Dalmatians before a pointer was crossed in to reintroduce it.

And it took decades and decades of fighting the closed registry dogma to get these Dalmatians into the breed. Even though they were very, very distantly derived from that pointer that was crossed in, the breed vanguards would not allow in the “mongrels.”

Until it became impossible to say no.

Every single breed in a closed registry system that is being bred with under these principles is at risk for winding up like the Dalmatian. What’s even more frightening is that as these breeds become more and more related through both popular sire problems and “line-breeding,” it becomes impossible to control for genetic load. Dog breeders operate under the delusion that you can just select away from any disease just like you’d select away from poor conformation, which is why they go ape over every genetic test for a disease that comes down the pike.

It’s not that these genetic tests aren’t useful. It’s that they do give dog breeders a crutch to hold onto. You can’t talk about  a better way to manage genetic load– i.e., let in new blood and selectively breed for better gene conservation– because everyone is awaiting the next genetic test to come along.

The problem is that the greater dog fancy is a culture that worships genetic plunder. Most of the effects of such pillage are not known while the pillaging is happening. During that time, a breeder might become rewarded with top winning dogs that may or may not have long lives.

But it is the next generations that the problems with gene loss and reduced genetic diversity start to become apparent. By then the breeder or breeders who plundered the genes may not even be around anymore.

But they have stolen from the next generation of dog owners and breeders.

It’s that next generation who will have to pay the vet bills and watch their dogs die agonizing deaths.

And all because we have contrived up endangered species that we call dog breeds and then bred them in ways that make absolutely no sense.

No one wants to talk about this genetic plunder.

And no one wants to talk about the simple fact that this concept of closed registry breed is really a very new concept. A breed is not a species. And although there are breed differences, when we start talking about breeds that are closely related, the differences become somewhat trivial.

And it is at this point the dog world becomes a dogma– a type of religion.

Breed becomes a faith-based assertion, and the dogs suffer because reason is not the operating force behind the management of their populations.

Dogma is.

Dogma is not good for dogs.

 

 

 

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Inbreeding is bad for dogs.

Do I need to say this again?

It’s bad for dogs.

The only people who think it is good don’t know what they are talking about– or they have been so severely indoctrinated into the dog culture that they can’t see it.

Yes. Indoctrinated.

In virtually all of these dog registry and competition systems, there is a strong desire to produce a high level of homozygosity in either behavior or conformation. You win more consistently if you have more homozygosity in your lines. It doesn’t matter if we’re talking shih-tzus or trial border collies. The tendency is to breed tightly and to breed to the dogs that win.

No one sits back and thinks about what this does to the dog populations in the long-term, because no one is really in it for the long term.  You’re in it to win it.

This means that dogs will continue to lose genes over time.  At the very same time, it will be these breeders who are forcing them down these tight genetic bottlenecks who will say they are improving the dogs.

They might be improving in one sense, but in another, they are impoverishing their animals with each successive generation.

The least obvious way in which they are impoverishing their dogs has to do with the immune system. You can’t see immune systems or the genes associated with them, but by golly, you can lose immune system genes.

The genes associated with the immune system are called the Major Histocompatibility Complex, which are called the dog leukocyte antigen (DLA) system. These genes are very easily lost when one is inbreeding or very tightly line breeding.

Now, in most domestic dog populations, breeders are operating within a closed registry system. These closed registries rarely allow new blood in, and if they do, it will most often be from dogs that derive from the same founding population– so it’s not really a new infusion of genes at all.

Then, you have another nice problem within closed registry systems. They demand that people breed only from the best dogs within that system. So certain winning stud dogs wind up siring a huge proportion of the puppies in each generation. Over time, many of these dogs wind up with very similar paternal ancestors, which means it’s very hard to produce dogs within the breed that are not highly inbred.

So you essentially have a system set up for the destruction of the domestic dog as an organism. Over time, the immune system will continue to weaken, coefficients of inbreeding will continue to increase, and the health and reproductive ability of the dogs will continue to fail.

Do we seriously want dogs to end up here?

Do we think all of these breeds are so unique that we can never allow a gene flow to exist between them?

If we think all of these things are true, then we have to accept the obvious consequence– the total collapse of many breeds.

And this analysis doesn’t even account for the tendency for deleterious and lethal recessives to be inherited in a homozygous fashion as a result of inbreeding.

If we are to be honest about saving dogs,  we need to tell these people who promote this toilet science of blood purity and who sanctify consanguinity that they are very wrong– and what they are doing is ultimately dangerous.

I don’t care if some breeder or some half-assed geneticist says it’s okay.

It’s not okay.

It’s going to destroy dogs.

Someone might get good results from a very tight breeding.

That’s not what I’m talking about.

I’m talking about population genetics and population genetics over time.

If everyone is doing that sort of breeding over a long period of time within a closed registry system, it is guaranteed to fail.

Massively fail.

But the institutionalized fancy and its token prostitute scientists continue to promote inbreeding and make apologies for its use that are so twisting of the actual science of dog biology that one wonders if these people might be closet creation scientists.

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This is a depiction that appears in Stonehenge’s Dog in Health and Disease.

Gowan’s Billy and Minnie are often circulated in Italian greyhound literature.

However, Billy’s pedigree, which Stonehenge extols, is often left out.

He was quite an inbred little thing, but Stonehenge does little but talk about his wonderful conformation.

This little piece tells us that the early fancy was obsessed with Bakewell’s system of breeding in and in.

Contrary to the scoffers, Italian greyhounds did have a purpose. They were little rodent catchers and were often crossed into ratting terriers to increase their speed. The Manchester terriers and the English white terrier had some Italian greyhound or whippet ancestry.

It is often said that Italian greyhounds are Italian, but that’s mainly because they became very popular in the states that made up Renaissance Italy. These dogs were always quite common in the courts of various nobles throughout Europe.

I seriously doubt that Billy’s ancestors were involved in anything but being pets and show dogs.

And the quest for perfection meant that his ancestor named Bill would appear so many times in his pedigree.

As one might expect, modern Italian greyhounds do have inherited health problems.

I’m not singling out this breed for being inbred. I just found Billy’s pedigree in that old book and laughed. Here was perfect example of the worst kind of inbreeding we all denounce in the blogosphere, and it was there from the early days of the fancy.

It was axiomatic that one would breed in-and-in to win.

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Source.

I remember having an argument (as school children often do) about whether Spuds was dog or a pig!

I love the name for this breed in Afrikaans: “varkhond.”

Yes. They call them “pig dogs.”

When I was in my late teens, this was one breed I was really into.

I read everything I could find about them.

I still have a very dog-eared book on bull terriers, which has all the breed lore and history in it.

Too bad the process of turning James Hinks’s bull and terrier strain into a dog that looks like a pig required a lot of inbreeding.

All dog breed are the result of breeding “in and in” as Robert Bakewell called his process.

NB:  I am not saying that modern breeders are inbreeding these dogs. I’m saying that the process that created them over the past century and half or so has left them with a depauperate gene pool.

I’m not making this stuff up. There is a well-known study of COI’s in purebred dogs, and this breed was most inbred.

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moderate golden

The results of a recent study in two provinces in Italy shows that purebred dogs and cats had nearly twice the number of spontaneous tumors than their non-purebred counterparts.

This study was performed in April 2005 using a telephone surveys. It is an interesting study.

Now, one should be careful generalizing form such narrow set of cases. After all, those provinces in Italy could have some sort of environmental conditions that affect the development of tumors in these animals.

Before I put too much weight into such studies, I would like to see  similar studies performed in other parts of the world. If the results are similar, then we can say that pure-bred dogs are at a greater risk for spontaneous tumors.

We do know that the genetic diversity of many purebred dogs and cats is lower than the genetic diversity in their mixed counterparts, simply because they are bred in a closed registry system that has just a few founders within that registry. This problem is further exacerbated with strong line-breeding, in-breeding, and the most-used sire effect. More inbred animals are known to have weakened immune systems.

That means that purebred animals are more likely to have compromised immune systems and, thus,  might make them more susceptible to cancer. That’s the theory about why so many inbred strains of vertebrate species are susceptible to cancer.

That’s why we should think about opening up registries.

***

Now I am going to have to muddy the waters a bit.

Check out this study

I’m citing it because it seems to contradict this line of reasoning, and as someone who tries to be fair on this blog, I think it is worthwhile to point out some interesting contradictions that sometimes appear in the scientific literature.

Now, don’t get me wrong. I’m for open registries for all sorts of reasons (mainly because most other studies contradicts this study.)

Anyway, I just posted this to engage in some dialogue.

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Here’s the much anticipated expose:

*Warning: Not for sensitive or younger viewers!

Part 1, Part 2, Part3, Part 4,  Part 5, Part 6,

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