Natural History

The effects of inbreeding are not the same in all breeds. Remember, it is inbreeding and then rigorous selection process that causes gene loss.  Different  inbred breeds have experienced the loss of different genes, and this is why we get some variance on the effects of inbreeding between different breeds. Some breeds handle it relatively well. Others come very close to extinction. (And many have actually become extinct.)

To illustrate these differences, it will be necessary to look at some case studies. I deliberately chose two breeds that have origins in the very recent past; both of these dogs were developed after the Second World War. Both were developed in Central Europe– one in capitalist West Germany and the other in communist Czechoslovakia. Both are the result of crossing established kennel club breed, and both were intensely inbred to establish type.

The two breeds are the Cesky terrier and the wolf-chow. As we shall see, the two breeds have very different experiences as they have been inbred. Because inbreeding almost killed it, one of them had to have the infusion of another breed to save it. And when that other breed was added, it became a new breed. The other still exists as it does, although there have been outcrosses with one of the parent breeds, it still has high levels of inbreeding.

The Cesky terrier was founded in 1949 in communist Czechoslovakia. The communists took control over the country 1948, and the breed founder, František Horák,wanted to create a hunting terrier that the “new socialist people” could take hunting the forest.  He wanted a small dog that could fit down nicely down

Horák began with a cross between a Sealyham dog named Buganier Urquelle and a Scottish terrier bitch named Scotch Rose. Only one puppy survived to adulthood, Adam Lovu zdar. That dog was trained as a hunting dog, but he was accidentally shot before he could produce any puppies. So Horák repeated the breeding, and six puppies were produced. One of these was Balda Lovu zdar, who was bred back to his mother, Scotch Rose.

And that began a long period of intense line and inbreeding with the Scottish terrier/Sealyham crosses.  Horák had worked as an assistant with geneticists at the Czech Academy of Sciences, so he was well-versed in Mendelian genetics. He rigorously selected for conformation and working characteristics, and the result was the only working terrier to develop in the Eastern Bloc.

Of course, we can criticize Horák for inbreeding, but Czechoslovakia at the time was not a place that was full Scottish terriers and Sealyhams for breeding. Many of the dogs that were in the country before the war dead, and during the war, no one was breeding from them. And to make matters worse, Czechoslovakia, as a communist country, was now cut off from the West, where most of the terrier blood was. Horák had to establish his breed with a smaller number of dogs than he might have liked, and to establish his line, he had to inbreed.

Today’s Csesky terrier is quite inbred. Many individuals have COI’s above 80 percent. However, the breed has no known genetic disorders, although the dogs are slightly susceptible to Scottie cramps. However, the breed does appear to  have issues with cancer and has a median lifespan of 8 years, 5 months. (One should be careful about that one study. It has an n=9. For the purposes of this post, let’s assume they do have issues with cancer.)

This breed is a good example of what rigorous selection can do to an inbred population. Because Horák and his successors were likely engaging in something very similar to natural selection upon this population. These dogs were selected for their health, vigor, size, floppy ears, and pack mentality. It is a sort of cheetah-lite selection process. Many working dog breeders who swear by breeding close and rigorously selecting are engaging in similar process.

And over time, the dogs were bred away from certain deleterious recessives. That is why the breed has no obvious genetic disorders.

However, continuous inbreeding still had an effect upon the breed. The high cancer rate in the breed is very likely the result of inbreeding depression. The breed likely has little diversity in the MHC.

Now, in the 1980’s, a Sealyham was crossed into increase genetic diversity in the Cesky.  Dogs that have this influx of Sealyham blood are called “Line 2″dogs, which differentiate them from Horák’s dogs, which are designated as “Line 1” dogs.

Although this breed has been selected against genetic disorders, it still has experienced the effects of inbreeding depression. It was only because of that rigorous selection process that genetic disorders were selected against.

One should not use the case of the Cesky terrier to assume that very tight breeding is okay. In that one instance, a very tight breeding program was able to work because of the selection process– and because the breeders miraculously did not select away or select for genetic diseases.

But even with that luck, they still have issues with cancer.

That is why many Cesky terrier breeders are trying to find ways to reduce COI’s in their breed. Even if the breed has survived and has thrived (in a relative sense) through very tight breeding, it does not mean that it will work in every case or even the majority of cases.

Dogs have not evolved inbreeding tolerance. The only wild dog population that has been able to survive exteme inbreeding has been the San Nicolas Island fox, which was able to survive and maintain a diverse MHC through balancing selection. The wolves of Isle Royale were once touted as being a great example of a thriving inbred population. That is no longer the case.

Generally, dogs do not do well in inbred populatons. As a wonderful counter-example to the Cesky terrier. the story of the wolf-chow is more indicative of what happens when domestic dogs are very tightly inbred.

A German named Julius Wipfel had always been fascinated by northern sled dogs. He settled in Weinheim, Baden-Württemberg, after the Second World War with his young wife. He then went looking for a dog. When he found a spitz-type dog at the local shelter, he jumped at the chance to take him home. The shelter said the dog had accompanied Canadian troops that had been occupying Mannheim. Maybe this was a ploy to get Wipfel to adopt the dog. Maybe this dog actually was a Canadian Eskimo dog. But whatever he was, the dog, who was named “The Canadian, ” had a profound influence on Wipfel. In Wipfel’s mind, he was the ideal sled dog of the northern type. He had very a “primitive” characteristics. He bonded very strongly with his family and was quite aggressive toward strangers.

When the Canadian died, Wipfel purchased a wolfspitz (keeshond) bitch. Like many of her breed, she was sweet and gentle– not at all what Wipfel wanted.

It was only after reading about a Chow-Chow/German shepherd dog cross in Konrad Lorenz’s books that Wipfel got the idea to breed Chows to wolfspitz.

He began breeding chows to wolfspitz and trying to build a club around these dogs. He called the breed the “wolf-chow.” However, he had a very hard time getting people to want to breed from them, and it became difficult to set traits.

His original breeding program required a rotation of different mating combinations of different wolfspitz and chow crosses and setting traits through selective breeding.

However, such a breeding program required lots of different dogs to be bred, and because West Germany was a mostly densely populated urban society, not many people wanted their dogs to be part of the breeding program.

Wipfel then came in contact with Charlotte Baldamus. She was a refugee from East Prussia who had many years of experience breeding poultry strains.  Now, in breeding animals for agriculture, the metric is very different from breeding pets. The metric for productive animals is the market for meat, eggs, or milk. Inbreeding to produce these animals is fine, simply because no one expects a chicken or a dairy goat to live out its full life. With dogs, we expect so much more. We want them to live out their full lives, and in doing so, we allow them have the potential of experiencing different genetic disorders.

Baldamus began an inbreeding program for wolf-chows. It required fewer breeding dogs and fewer generations to set type, and the results were very much what she was expecting.

However, as the program continued, COI’s got higher. This was exacerbated when the whole breed was essentially built upon one red stud dog.

The dogs looked like what they wanted, but they were of no use as sled dogs. They also begant os show signs of an inbreeding depression and hip dysplasia showed up for the first time. Wipfel wanted to cross in Samoyed dogs, but Baldamus did not want any new blood.

It was only when Konrad Lorenz, who had admired this breeding program because it was based upon his own work, suggested that Samoyed be added into the breed. Wipfel did so, producing a litter of black puppies– and Lorenz purchased one. Black puppies shouldn’t have been a surprise. Samoyeds are black-skinned e/e’s. For some reason, the e/e genotype makes the Samoyed white instead of cream or gold, as we see in golden retrievers.

But when the Samoyed was crossed in, the primitive temperament that Wipfel wanted to hold onto disappeared. The Chow’s strong bonding tendencies were swamped with the friendly and gentle natures of both Samoyeds and keeshonds/wolfspitzes.

When the breed was officially recongized, the Chow fanciers club refused to allow them to register the dogs as “wolf -chows.” So it was decided to incorporate the Samoyed influence in the breed’s name, calling them Eurasiers to reflect the origins of their ancestors in Europe, Siberia, and China.

The wolf-chow was not selected for working characteristics as the Cesky terrier was. It was selected for appearance only. And the selection process for the wolf-chow did not select against disease. Without an understanding of which genes are associated with which disorders, selective breeding at this time was a crap shoot. The Cesky terrier breeders had been lucky that they selected against genetic disorders. The wolf-chow breeders were unlucky in their roll of the dice.

And they were not rigorously selecting for health. They were breeding dogs as if they were poultry.

And the results were not good.

Most dog breeding in Western countries would involve the selection pressures in the wolf-chow. Very few breeders are engaging in rigorous selection that would produce a dog like Cesky. Even if they are breeding for health, the dogs are not going to undergo that selection process.

Many working dog breeders use something like the Cesky breeding strategy. They even make their bitches whelp outside in doghouses or steel barrels so that natural selection also acts upon their breeding programs.

And that is one way to select against genetic disorders.

But over time, inbreeding is inbreeding, and some effects of an inbreeding depression still pop up, such as the Cesky terrier cancer rate.

Now, most modern dogs are not bred in the same way that wolf-chows and Cesky terriers were. Most dog breeders use line breeding techniques, but the results can be similar, though far less dramatic in the short run.

The truth is that inbreeding and the selection process can cause no problems in terms of the health of a dog breed or line. It can also cause very real problems for a breed. Our understanding of dog genetics is still not complete enough to understand why it causes problems in some cases and not in others. And even if our understanding is better than it is now, we can still have surprises. The genome has many surprises for us, especially when we think we know it all.

For that reason, as a precautionary measure, it is best to see inbreeding as something to avoid and genetic diversity something to promote. And even if things wind up being okay for a time, it does not mean that something might go wrong someday. (See the Tasmanian devil’s story to see why.)

One can use stories in which animals, including other domestic dog breeds, have done relatively well through inbreeding. However, the only dog I have found that has an even half-way good outcome from inbreeding is still experiencing what appears to be an inbreeding depression. We cannot base our whole model for dog breeding off of this one case. History has shown that when dog loose genetic diversity, the have experienced more like that of the wolf-chow than the Cesky terrier.

The risks are just too high to ignore the COI and diversity within the MHC/DLA genes in domestic dogs. And just because it worked out once (kind of) does not mean that it will work in every case or even the majority of cases.

And just as it appears to work at one point does not mean that there are no long-term consequences.

Both of these breeds were founded from small numbers of dogs out of necessity. The were both created in social and economic situations in having large kennels was simply impractical.

Most of our kennel club breeds are actually derived from breeders who did have many, many dogs to choose from and the founding populations were actually quite large. And very tight breeding was not often pursued without using outcrosses, which often came from lines produced in the same kennels.

Inbreeding was a way of establishing a breed quickly with just small numbers of dogs.

Because of these factors, most modern dogs have gone this same direction but at a much slower pace.

But the story of these two breeds should tell us what could potentially happen with genetic bottlenecks– even when things appear to be going fine.