Auburn veterinary professor comments on “designer dogs” and dog breeding

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Dr. Bruce Smith of Auburn University’s College of Veterinary Medicine answers questions about so-called “designer dogs” and dog breeding. Recent news articles, such as “The creator of the labradoodle says he made ‘Frankenstein’s monster,’” are bringing into question the issue of “designer dogs.”

What are designer dogs?

These days, people use the term “designer dogs” to refer to new mixes of breeds. However, I think that is a misnomer. Technically, all domestic dogs are “designer dogs.” The domestic dog may be the first genetically modified organism (GMO) created by humans. Ever since a few wolves with gene variants that made them more curious or less fearful of humans started hanging around the campfires of our ancestors, we have been manipulating the genetics of dogs. Over the past 20,000 or so years, we humans have intentionally bred dogs by selecting parents with desirable traits and then deciding which of their offspring best matched our needs (hunting, herding, hauling, etc.). Interestingly, most modern dog breeds have been derived within the past 300-400 years. Many of those were created by cross-breeding two or more early breeds to give some new, desirable, combination of characteristics. The Labradoodle, the dog that started the current “designer dog” phenomenon, is no different. Wally Coonron, originator of the breed, was looking for the personality of a Labrador retriever combined with the hypoallergenic coat of a poodle. He had a specific need, and just like everyone that preceded him, he selected parents based on the traits he wanted to see in the offspring. However, many other individuals, seeing a market for interesting combinations, and a potential for profit, started making all kinds of crosses, many with no real focused need. That focused need is important, because it drives selection of only those dogs that actually have the desired trait. And in reality, that’s not as simple as just breeding a Labrador retriever to a poodle and training their puppies to guide the blind. In fact, the genetics of these crosses even raise some very serious questions about the suitability of these dogs for their intended purposes.

What happens genetically when a dog is bred to a closely related dog?

Let’s start with the opposite, what happens when distantly related dogs are bred. Using the case of the Labradoodle, if a Labrador retriever is allergenic and a poodle is hypoallergenic and we assume this is due to the genetics of each breed, then what will a cross look like? Using the best possible case, that the hypoallergenic trait is a simple dominant trait and that the version of the gene for the trait are “fixed” (that is, there are none of the other type of gene in each breed…no Labradors with the hypoallergenic flavor of gene, and no poodles with the allergenic variety) then the puppies from the first cross will all be hypoallergenic because they got that gene from their poodle parent. But, and it is a big but, they will also all carry the gene for being allergenic, because they all got that from their Labrador parent. Now, how do we get the second generation of Labradoodles? We can do that by breeding more Labradors with poodles or we can start breeding Labradoodles. If we do the latter, we go the dreaded Punnett Square (that many of you learned but have since tried desperately to forget) and see that three-fourths of the offspring will be hypoallergenic, but one-fourth will be allergenic! It’s even worse if we think that the hypoallergenic trait is recessive. If that were the case, NONE of offspring of a Labrador crossed with a poodle would be hypoallergenic because they would all have one copy of the allergenic version of the gene from their Labrador parent. It would only be in the second generation that we would see hypoallergenic dogs, and it would be limited to only 25 percent of the puppies!

Dog breeds become breeds by continued breeding of dogs in a line from a limited group of founders. Mating closely related dogs can create many genetic problems. The reason for this is that most genes that cause problems are recessive. By mating relatives, the chance that the offspring receives two copies of the recessive gene is increased and so we commonly see increased rates of genetic disease in matings of close relatives. Unfortunately, that is one of two major sources of genetic problems that can be seen with designer dogs. In this case, with very few original dogs, it may be necessary to mate relatively closely related dogs to expand the “breed.” This is not just a problem for these “fad” designer dogs, but also for relatively rare breed of dogs. The second source of genetic problems with designer dogs are the unscrupulous people who simply make these dogs for financial gain, without regard to the background of the dogs that they are using, or to the quality of the puppies that they produce. A Labradoodle that comes from the neighbor’s Labrador that got loose and produced puppies with the poodle down the street is not going to have the same genetics as one that has been produced by thoughtful breeding.  

Do designer dogs have more inherent health problems?

I have to say that it depends on a lot of issues. If we are talking about puppies produced in a cross between two breeds, it is actually likely that those puppies will have fewer genetically based health problems because you have the offspring of two unrelated dogs. If, however, you then breed these puppies with each other to produce more designer dogs, then you are likely to have far more genetically based health issues. One way to combat this inbreeding problem is to create a large number of the cross-bred dogs and to use many or most of them in the subsequent breeding to enlarge the new “breed.” The more unrelated dogs that are used, the less likely that there will be an increase in genetically based problems. As these designer dogs achieve “breed” status themselves, they face the same issues with genetic health problems that face current breeds. These include inbreeding, where there just aren’t enough dogs in the breeding pool, founder effects, where the contribution of a small number of founder animals is shared by the entire breed, and popular sire effects, where one or a few very desirable sires are used for almost all the breeding within that breed. The mutations in those sires then appear in many of the puppies and spread rapidly through the breed.

How do designer dogs differ from purebred dogs?

In reality, today’s designer dogs are just a few generations away from being considered as purebred dogs in their own right. Typically, designer dogs are a genetic mix, and as I noted above, they can express traits in a very variable way. Often, when bred to each other they produce a variety of appearances in their puppies. In other words, designer dogs fail to “breed true” and can be very different from one another with respect to many traits. Over time, as these dogs are bred to each other and desirable traits are selected for, and undesirable traits selected against, the genetics of that breed will become more homogenous and pairings of dogs with the group will breed true. That is, they will produce dogs that match characteristics of the parents and the other dogs in the breed. An example of this can be seen in the Australian Labradoodle, which is attempting to achieve breed status with kennel clubs around the world.

Should a pet owner look for certain traits when considering getting a designer dog?

A pet owner should look for the same thing in a designer dog as they might in any purebred dog. The first thing that a potential owner should consider is suitability. It saddens me to see dogs in home situations that are clearly not suitable for the dog. For example, lots of people want to get Australian shepherds. These are awesome, highly intelligent, loyal dogs, who will understandably go stir crazy living a suburban life, left at home all day while the owner goes to work. Too many of these dogs are relinquished for bad behavior when the reality is that the behavior is due to owners ignoring the need for these dogs to have work to do.

The second issue is to look carefully at breeding and genetics. If you are not obtaining a dog from a humane society or rescue, you should obtain the dog directly from the breeder. In the process, the breeder may insist on interviewing the potential buyer. Potential buyers should also interview the breeder. You should be able to see the mother, and where the puppies are living. You should be able to get a complete health history on the puppies, their mother and their father. It is always a good idea to search the internet for potential genetic problems in a given breed. There are too many sources to list, but the best ones are either from overarching organizations like the American Kennel Club, or from breed club websites. As always, not everything you see on the web is true, so be wary of sites posted by individuals who may have a vested interest in hiding potential problems. If you do identify that the breed you are interested in has the potential of a genetic disease and a genetic test is available (and here I’m talking about a specific test for the disease-causing mutation, and not the “what breed is my dog” type of genetic test) make sure that the breeder has tested their breeding animals for the disease and they are disease free.

Finally, be forewarned that so-called designer dogs being sold by individuals or through third parties, such as pet stores, may not even be the breed that they are claimed to be.

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