Both the National Geographic article and the Dogs and More Dogs movie talked about the adverse affects that can come from artificial selection and pure-bred breeding.
When dogs started to be bred for their looks instead of their abilities, this lead to more breeding for purebreds, which is usually accomplished through inbreeding, which in turn leads to more genetic diseases and disorders. This cycle can be traced back to Victorian England times when dogs became a status symbol. There was a rising middle class and to show that they had arrived in society, they would get a dog. Showing that you had the money to keep and feed an idle pet was very much a wealth symbol at this time.
This is where the importance of bloodlines started. Only purebreds are allowed in dog shows so knowing the bloodline of your liters are very important. One of the only ways to know for sure that you have a complete purebred bloodline is to introduce inbreeding. Having moms mate with sons, daughters with grandfathers, cousins, aunts, uncles, etc. is an easy way to make sure that good genes stay in the family and you don't introduce any bad genes. The problem is the only genes you are artificially selecting for our physical traits. Without genetic testing there is no way to be sure what bad, deleterious genes that code for diseases you are also passing on to your "perfect" Papillion. You might have offspring with the perfect ears that come out of the head at the perfect 45 degree angle and you might get the perfect head size where the head accounts for 2/3 and the snout for 1/3 but you might also be passing on genes for a fatal disease.
The National Geographic article even suggests that simply becoming domesticated allowed for deleterious mutations, which would have been weeded out in the wild, to become selected for and even advantageous. When people were trying to make new breeds, the more distinct of a dog they could breed the more likely it would become a new variation so breeders would go for single genes that would have a larger impact on the phenotypes, not really be concerned with what is happening to the whole genotype.
In the movie, the Papillion breeder seemed to think that the obvious and simple (to her at least) answer to genetic diseases was to perform genetic testing on the dogs and to simply not breed those dogs that have bad genes. Thinking that all breeders will take the time and the money to do this is a bit extreme.
Although these genetic diseases are sad and unfortunate for dogs, they have an upside for humans. Hundreds of dog diseases have been mapped to mutations in particular genes. Many of these dog genes have human counterparts. Only a few bad genes have been identified for behavioral disorders in dogs. One of these genes is the gene that induces OCD in Doberman pinschers. These dogs obsessively suck on their fur to the point of bleeding. This is simple a bad "side-effect" of breeding different mixtures of dogs.
The movie addressed some different behavioral disorders in dogs including nervousness in pointers to the point of paralysis where the dogs are so scared/fearful/nervous that they freeze and you can move them and they will stay in whatever position you put them in. They are truly like autistic or schizophrenic humans where they simply cannot interact with their environments.
The movie also talks about narcoleptic Dachshunds. It is much easier to study diseases in dogs because they have so much less genetic variation than humans. The movie talked to the researcher who found the specific gene that contributes to narcolepsy in these Dachshunds and he believes that researchers can then find the human homolog gene and start working on new medications.
Something I found really interesting in the movie was that millions of dogs get euthanized a year and a lot of those dogs aren't even "sick". Many people have to give up their dogs or put their dogs down because they are "misbehaving". The movie gave a different view though, one that I like a lot more. It suggests that misbehaving dogs aren't "sick" but the behaviors bred into them are simply a bad match for the life they are asked to live. If you live in a small apartment, you are going to want a dog that doesn't bark too much or shed. So these people go out and buy a dog with a low maintenance coat like a Dalmatian. The thing is Dalmatians can run 30 miles a day and not be tired. They are not apartment dogs. So then when the Dalmatian is too energetic for an apartment, the owner thinks there is something wrong with the dog. I have grown up with retrievers and I know that we have to take them outside and throw a ball or a retrieve every night or else they get really cooped up and go crazy in the house. They are not being bad dogs, they are simply reacting to the instincts in their genes.
This movie really made me think about how much thought and consideration you have to put into what kind of dog you want to get and what kind of lifestyle that dog will be living. To make the best life for yourself and your dog, you need to find a dog that fits into your lifestyle and not your aesthetics.
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