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Posts Tagged ‘outcrossing’

lundehund puffin

The Norwegian lundehund is one of the most inbred dog breeds in the closed registry system, and I have questioned the wisdom of including this breed into a dog population management culture that celebrates blood purity over health and good science.

Because of its peculiar adaptations for traversing rocky cliffs and squeezing down puffin burrows, there is a tendency in this breed to believe that it is too unique to have new blood added. If you add new blood, the dogs cease being lundehunds– which is actually theological reasoning and is unfortunately all too common in the world of purebred dogs.

All lundehunds alive today derive from six founders, and five of these were all from the same mother.

That is not a very large founding population, and when a breed is placed into the closed registry system and bred to a particular standard, a lot of genetic diversity will be squandered. If you start out with a population that is already quite small, the effects of such breeding practices will be magnified.

This breed has a condition known as “lundehund syndrome,” which is just a shorthand for a variety of gastro-intestinal disorders that affect this breed, which can range from mild issues of malabsorption of nutrients to cancer of the intestines. It is estimated that anywhere from 40 percent to 100 percent of this breed suffer from some variant of the disorder.

There is definitely some sort of genetic basis for the syndrome, but no one has been able to say what might be done to rectify the problem.

Further, the breed is also suffering from a general inbreeding depression, which means the breed is eventually on its way to extinction unless something is done. The breed is rapidly losing its fertility, and without new blood, they may simply become impossible to breed.

And the Norsk Lundehund Klubb (Norwegian Lundehund Club in Norway) has decided to begin an outcross program to save the breed.

The club recently announced that a lundehund had been bred to Norrbottenspets, a small treeing spitz from Norway that is known for its prowess in treeing forest grouse. The club’s announcement reads as follows:

The Norwegian Lundehund Club has initiated a project to increase the genetic diversity of Norwegian Lundehund. This is absolutely adamant now as this very special dog breed is on the verge of extiction (sic). Norwegian Lundehund is one of the most inbred dogbreeds (sic) in the world, and it shows indications of reduced fertility. In the long run, inbreeding depression might be the end of this wonderful dog breed, and we cannot sit still and watch this happen. The first cross has taken place, a Norwegian lundehund male and a female of Norbottenspets. This had to be done by insemination as the male, unfortunately, was too small. The puppies that we hope will be borne in two months time, will be registered at the Norwegian Kennel Club in an x-register, and they will not be sold on the open marked. For all of you that own a lundehund, keep up your breeding programme, as there will be many years until any individual that is a result of crossbreeding will be introduced in the true breed. We hope to save the breed, but we need your help to keep up the numbers of truebred (sic) lundehunds over the years to come. More information will be available on our homepage and fb within a few days.

So when a breed is faced with extinction through poor population management, the only solution is to make radical steps to save it.

Of course, these steps aren’t radical at all. If people were not so accepting of the tenet of faith that blood purity at all costs is a virtue in domestic dog breeds, this breed would be as healthy and viable as any other.  New blood would be brought in every couple of generations, and the population would be carefully managed.

But this concept– which is essentially without controversy in the scientific animal husbandry literature as well as the literature on population genetics– is utter heresy in the world of dogs.

To cross breeds is the ultimate sin– something that only done when there is no alternative.

It is really sad that this breed had to come to this point before the Norbottenspets outcross program was accepted.

But the truth is all of these other breeds are in the same boat. They aren’t moving at exactly the same pace as the lundehund, but they are all moving in this direction slowly but surely.

It really is time to drop the blood purity cult.

It’s just not serving the dogs well.

Period.

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One of the common arguments for maintaining the closed registry system is that as soon as one does an outcross it will be impossible to breed back to the original phenotype.

This is actually not true, and with dogs, it does not take many generations to breed back before the dog looks and behaves exactly like the purebred.

I have already mentioned a nineteenth century program that introduced bloodhound into the British basset hound population to save it from an inbreeding depression. I have also mentioned Bruce Cattanach’s bobtailed boxer program, which used a naturally bobtailed corgi to introduce the trait into the boxer. In both cases, the dogs were able to return to their original type through relatively few generations of breeding back into the boxer gene pool.

Cattanach writes about how quickly he could breed dogs that looked very much like pure boxers:

The transformation in one generation can only be described as amazing. It suggests that very few genes are responsible for the main features distinguishing the Corgi and Boxer, except for the special Boxer head. The white coat colour, of course, was Boxer white and resulted from the doubling up on Boxer.

That’s right. Just a few genes separate all of these dogs breeds. Variation on only a single gene explains most of the wide variance in size among dogs.  Size is very easily selected for in breeding programs, which is why we have three widely varying sizes of poodle that all descend from essentially the same stock.

If a breed has a particularly specialized head, it may take few more generations to “fix.” The bull terrier in Britain was traditionally a white dog. After all, it was derived from the English white terrier. The English white terrier went extinct because it developed severe genetic genetic problems– among them deafness. Deafness also affected the white bull terrier breed, and it was feared that it would follow its white terrier ancestor into oblivion if something was not done to correct it. The English white terrier was extinct by 1900, and within just a few years of its extinction, crosses between bull terriers and a few select Staffordshire bull terriers occurred. One of the staffies used in the program was a first cross between a bull dog and a Manchester terrier.

Although it was easy to return to the bull terrier phenotype, it was very hard to breed the special bull terrier head in the colored lines. Bull terriers have a very specialized, egg-shaped head, and they also have triangular eyes, which were very hard to fix in the colored lines. The prevalence of “button eyes” in colored strains led some fanciers to denounce them as mongrel, and it is one of the reasons why the AKC has two separate varieties of bull terrier: white and colored.

However, even those button-eyed coloreds looked very much like bull terriers. Perhaps if the bull terrier fanciers had been more open to breeding from them, they would have become more or less like the white dogs much more quickly.

But through backcrossing and selective breeding, the colored bull terriers now have classic bull terrier conformation. One even won best in show at Westminster  in 2006.

Simply put, the argument that it is impossible to breed back traits after doing an outcross is simply bogus. The fact that it takes just a few generations of backcrossing to produce a dog that is virtually identical to the backcrossed breed shows how easy it is.

Albert Payson Terhune evidently knew of this fact when wrote the story of a collie named Buff. Nina, Buff’s mother, was an accidental cross between a collie and pit bull, and she accidentally mated with a top show collie. Buff resembled a perfect show collie, even though his grandsire had been a pit bull.

There actually was a collie named Buff. His photo appears in the frontispiece of the book, but I do not think that this collie actually had this ancestry. It is possible, but I doubt it.

The rapid effects of backcrossing in dogs have been well-established for quite some time. Stonehenge (John Henry Walsh) was quite aware of how easy it was to return to phenotype after just a few generations of backcrossing. He used an experimental crossbreeding between a bulldog and a greyhound. Writing about this crossbreeding and back crossing program in his The Dog in Health and Disease (1859), Stonehenge points out how quickly it easy to produce dogs that resemble greyhound from backcrossing:

It might naturally be supposed by any person who has not been convinced to the contrary, that it would take several crosses to get rid of the heavy form of the bulldog when united with the light and graceful shape of the greyhound. But on actually trying the experiment it will readily be seen that in the third generation very little trace remains of the bulldog, while in the fourth there is none whatever apparent in external form. My friend Mr. Hanley is the last who has tried the experiment, and having kept a daguerreotype of every individual used in it, which he has kindly placed at my service, I have been enabled to present to my readers perfectly trustworthy proofs of the correctness of this assertion. The bulldog “Chicken” used was a very high-bred animal, and of him also Mr. Hanley has preserved a daguerreotype, but as his blood is very similar to that of Mr. Stockdale’s “Top,” I have not thought it necessary to engrave him. The bitch “Fly,” put to “Chicken,” was also highly bred (pg. 179).

One must note that Stonehenge writes that Chicken was nearly identical to a bulldog named Top, which he depicts in his section on bulldogs. The first cross between Chicken and Fly, called a “Half- and-Half,” is a meld of features from the greyhound and this old type of bulldog:

The “Half-and-Half” was then bred to a greyhound named Blunder, and this breeding produced a white bitch named Hecate:

Stonehenge describes Hecate:

From these came the second cross, “Hecate,” a white bitch still presenting some slight characteristics of the bulldog breed, but by an ordinary observer this would be scarcely noticed. There is, however, a remarkable want of symmetry and true proportion in this bitch, which the portrait conveys exactly (pg. 181-182)

Hecate may not have been what greyhound fanciers wanted in an ideal specimen, but she doesn’t look all that much like a bulldog. She just looks like an “off” greyhound.

Hecate was bred to another greyhound named Preston. He was a very fast dog, and it was thought that he would pass on these traits to his offspring. One of the puppies produced from that breeding was a black bitch named Hecuba:

Stonehenge describes Hecuba as “a large black bitch of good shape, and, as I before remarked scarcely distinguishable from the pure greyhound” (182-183).

She was a very fast dog, but she lacked stamina. This finding suggests that certain working characteristics might be hard to breed back through backcrossing when the original outcross is between two very different breeds.

Hecuba was bred to another greyhound named Bedlamite, and the offspring that resulted from this litter were fast but were deficient in “stoutness.” Stonehenge shows a depiction of one of these dogs. Her name is Hysterics, and she is very clearly a greyhound.

Hysterics was then bred to Ranter, her full greyhound half brother, and the puppies that resulted from that breeding were not as good as the fourth cross. Perhaps such tight breeding caused these deficiencies.

So even in Stonehenge’s day, it was well-known among dog fanciers that it didn’t take many generations of backcrossing from an outcross to produce dogs that had the correct phenotype.

And in Stonehenge’s day, Gregor Mendel’s work was not yet accepted as science. Although Mendel was conducting his experiments at the time of Stonehenge’s writing, his work was essentially unknown to the British public.

Now, we have a much more complete understanding of genetics. It is not complete by any means, but we know how many traits are inherited dogs. Because we have this knowledge, it will be easier for us to engage in cross-breeding and backcrossing programs. We also know how to test for many genetic diseases, and we can test both breeds used in these programs for certain inherited diseases.

We know so much more than they did, and we could use crossbreeding and backcrossing programs to improve the health and diversity of many breeds.

However, institutionally, there are many barriers to these programs. The Dalmatian Backcross Project has produced Dalmatians with low uric acid concentration in their urine. Uric acid stones are major problem in the breed, so it was decided to make a cross with a pointer and then backcross to produce Dalmatians that have low uric acid concentration. After generations of backcrossing, these dogs are now 99.7 percent Dalmatian.

But the AKC and the Dalmatian Club of America have been resistant to allowing these dogs to be registered. The AKC recently deferred the decision to include these dogs to the Dalmatian Club of America. The DCA still refuses to accept them. The DCA has also started a propaganda campaign in its own literature, claiming that if such dogs are allowed in, the Dalmatian will no longer be purebred and the health of the breed will deteriorate.

All of these things are unlikely to happen, and if a dog has an old pointer ancestor but still looks and behaves like a Dalmatian, what difference does it make? The average dog owner might want a dog that looks like a Dalmatian and acts like one, but they also want one that is healthy. I don’t see what the big deal is– unless purity is such an overarching virtue that one “bastardization” several generations back negates the  validity whole strain. Such a position is actually quite hard to defend to the average person looking for a dog, and this might not be the best public relations step to take.

Backcrossing allows the breeder an opportunity to return to phenotype and working ability. It allows those genes to return to the bloodline, which also has the genes from the outcrossed breed. If those genes add something to dog– such as a healthy urinary tract or a naturally bobbed tail– then these outcrossing projects are worthwhile endeavors.

Because of the successes of these sorts of programs, the dog world should be more willing to operate with an appendix registry system. As we saw with the greyhound/bulldog project, not every dog produced was worthy of breeding– as is the case with purebreds. An appendix registry allows dogs that meet some of the breed requirements to be registered, and then these animals can be bred to the other dogs in the registry. When puppies are born, they are also checked to see if they fit the criteria and are registered accordingly.

The cat fancy has totally embraced the crossbreeding and backcrossing of many different breeds. The CFA allows certain breeds– such as Persians and Exotic shorthairs– to be crossbred. These two cats have very similar conformation, just one is long-haired and the other is short-haired. The animals are crossed and registered according to phenotype– something that was done in retrievers and spaniels for decades.  Cat fanciers are given a greater opportunity to selectively breed from diverse bloodlines than dog fanciers typically are.

Crossbreeding and backcrossing are tools that should be open to more dog breeders. They are tools that do require skill to use properly, but the skills can be learned. They require understanding the genetics of what makes up a particular breed or variety and that of the outcrossed breed. This sounds very scary to many traditionalists within the dog fancy. It needn’t be.

In the nineteenth century, they were doing these crossbreeding experiments with no real knowledge about health or genetics.

And the dogs didn’t fall apart.

We know so much more now. And it is time we get a chance to put that knowledge to work to build a better future for Canis lupus familiaris.

 

 

 

 

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What do dog breeding and economics have in common?

They are both dismal sciences.  They appear to have little in common, but the truth of the matter is they actually share a certain amount of similarities that leads to me to make some analogies. I am not a trained economist, but I am a political scientist, who has been trained in some economic theory. If I get something wrong in this post, it is because I am not an economist by trade and because I am oversimplifying for the purposes of making an analogy.

When Thomas Carlyle described economics as “the dismal science,” he was actually writing a very bizarre and racist essay on why the British Empire needed to re-institute slavery in the West Indies. He contended that slavery was better for the moral development and economic security of the people of  the West Indies. However, there is some suggestion that his critique of Malthus, who wrote about the virtues of letting the “excess” poor starve to death, may have been where he first called economics a “dismal science.”

But I think the reason why it is called a dismal science today has very little to do with Carlyle.

One part of economics looks at the various trade-offs associated with policies and decision. The best known type of this analysis is the Cost-Benefit Analysis (CBA), which has been used in the US since the 1980’s for budgeting purposes. The ideal economic policy is one where the costs are totally outweighed by the benefits. The problem with doing these type of analysis is we don’t always have “perfect information”– that is we don’t know what all the real costs and benefits inherent in the policy or decision are, nor do we know what these could be in the future.

That’s why things get to be dismal. Even before the formal CBA became part of many policy making decisions, economists were always looking at costs. When one policy is pursued, another is not or some “horrible” is risked. Because we don’t have perfect information, the best economists are always looking for these potential costs and pitfalls in order to get the best information possible.

I think the Eagles got this issue best with this line from the song “Lyin’ Eyes“:

“I guess ev’ry form of refuge has its price.”

And if you think about it,  it fits– although economists would change “price” to “cost.” (Price has a very different meaning in economics.)

Harry Truman once said, “Give me a one-handed economist! All my economists say, ‘On the one hand on the other.'”

And that’s exactly how economists think.

But in a weird way, it is also how dog breeders think.

At least that’s been my experience.

Every possible decision that a breeding program makes has consequences– some of them negative and some of them positive. This is the “micro-economic” equivalent of dog breeding.

Every breed club or registry makes policy that also has also consequences for the breed at a much more macro-level.

Dog breeders want to produce dogs that 1. have good temperaments, 2. have good health, and 3. have some qualities that make the dogs superior in either conformation or some defined behavioral trait.

There are lots of ways to do this.  If one wants consistency, one line breeds. If one is really experienced and wants certain traits established in a line, close line-breeding and inbreeding can be used. One can also use those methods to cull out particular genetic disorders and conformational faults. This is actually what is described in most dog breeding manuals.

However, there are negative consequences to doing this. Over many generations, the genetic diversity of a line becomes weakened. One can experience what is called an inbreeding depression.  Over time, the animals lose their fertility and ability to thrive. However, it is very hard to observe this phenomenon unless one has been in a breed or strain for a very long time. Inbreeding depressions are ultimately comparative, because the fitness and fertility is something that is reduced over time. If one does not know what the original fitness was, one cannot see the inbreeding depression. However, that does not mean it is not real.

So one should be open to outcrossing with other lines. Because of the way most registries operate, one can only breed with other lines of the same breed.

However, here’s the “on the other hand.”

Outcrossing does increase genetic diversity. However, it can also introduce bad things you didn’t see before. Maybe the other line has a hidden genetic disorder that the breeder suddenly introduces into his or her line. Or maybe the other line has traits that interact very poorly with the genetics of the original line. Maybe the dogs are developing bizarre conformation, or they simply lose their working abilities. It is always a “horrible” that exists when bringing in new blood to counteract the effects of line breeding and occasional inbreeding.

Such problems that result from outcrossing are what is called an outbreeding depression.Outbreeding depressions happen whenever crossing two populations results in offspring that are either poor fits for the environment or task at hand or results in offspring that are unhealthy.

Here’s a good example of an unplanned outbreeding depression–my “golden boxer.” This dog was a terrible guard dog, as one would expect from a golden. However, she was a terrible swimmer with no retrieving instinct.  She had the traits of both breeds. It’s just she had them in ways that were incompatible with either being a retriever or being a watch dog. The boxer line she from which she came had a very high amount of osteosarcoma, and it is from that disease that she died at the age of 11. Her “inbred” dam was a golden retriever who made it to the age of 14.

Now, these same consequences exist at the registry and kennel club level. However, the consequences at this level affect more dogs and affect the entire population in the registry or kennel club for the long term.

We can keep registries closed and allow breeding only with dogs in those same registries. We will be able to maintain some consistency in type and behavior over the entire breed or strain. In performance registries, we will get consistency in the desired behaviors. We will also be able to get some handle on the genetic diseases– at least in the short-term.

We can also allow breeders to breed from just a select few studs, which produce huge chunk of the puppies born per generation. This also will allow the breed to have consistency in type, behavior, and disease.

But at some point, these genetically depauperate breeds and strains are going to experience trouble. The inbreeding depression problems will pop up, and reduced genetic diversity always makes the immune system weaker over the long term, which can mean digestive issues, skin problems, and maybe even  increases in cancer.

So what can what can registries do about this problem?

Well, they can open the registries. That will allow a gene flow between populations again, and it can take care of some of the problems. It can reshuffle the genetic deck so that dogs don’t get exposed to negative recessives. It can eliminate some of the problems associated with the inbreeding depression. Over the the long term, it is likely that it could have very real effects on these gene pools.

But there are problems here, too.  One is that the consistency in conformation will disappear, and if one breed is known for its working ability and the other is not, it is possible to introduce nonworking characteristics into a strain. This is also an outbreeding depression but at a much larger level.

Let me make myself clear: I am in favor of opening up the registries. I do not think in that in the long term the breeds are all that viable.

But when I say this, I’m also aware that there are potential negative consequences to doing this. The most obvious of which is the breeds are not going to be as consistent in type and behavior, and the other is that if related breeds are used as outcrosses, the differences between related breeds are going to become little more than theme and variation on the same dog. I am willing to accept some of that.

And I am also aware that we are not going to breed out genetic diseases. It’s impossible. All organisms have genes for bad things. It’s just the way things are. One can line breed and inbreed to cull these diseases. I think this is illusory in the long term, because at some point, the diseases caused by negative recessive are going to line up and a whole new disease will pop up. It’s not a matter of if. It is a matter of when. And what are you going to do? Line breed and inbreed until you get rid of that?

In the long-term, breeders would be better off focusing on genetic diversity rather than trying to breed out everything, but of course, that has all the possible negative consequences I’ve just mentioned.

Also, not all genetic diseases are recessive or can even be answered with simple Mendelian genetics. With those, the answer is far more complex.

And all of it is complex.

I think it ultimately comes down to how much variance a breeder can tolerate and how consistent a breeder wants to be with his or her line. In the old days, this was actually much easier, for breeders kept their own distinct lines, which they would use as outcrosses every couple of generations. Most breeding today is a collaborative effort, and that means dealing with another person’s desires and goals. Different people will have different ideas about how much variance will be tolerated in the dogs.

So what is the solution to all of this?

I think the solution in the end is to give breeders more freedom to use whatever breeding system they feel is appropriate. I’m not for banning inbreeding and close line breeding, but such breeding cannot exist within a closed registry system. It is asking for trouble over the long term. If we are to maintain a closed registry system, then we are going to have think hard about how many litters a stud can sire and how often a breeder should outcross.

But still, we have to keep in mind that breeding “in and in,” as Bakewell did, and outcrossing both have positive and negative aspects. Those of us who advocate for greater genetic diversity in dogs and more open registries should at least admit this reality, and we should also admit that opening the registries doesn’t always solve the problem and can have some negative consequences.

I think that if we tried to talk like this, we might be able to get a dialogue going.  And if we have a dialogue, maybe we can actually come up with ways to solve these problems.

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