That's a whole bunch of questions. I'll take a stab at a couple of points.
On the subject of what is a pure bred dog, it all depends on how you look at it. You could say that all pure bred dogs are designer dogs since they were created from mixing various dogs until a desired type was set. Shoot, you could even turn that around and say that all dogs are pure bred, in the strictest sense, since they were all bred from the wolf. Of course, that isn't REALLY true as there are many sub-species of wolf, so you're back to square one.
So let's stick with the modern notion of a pure bred dog. Yes, breeds can become messed up, but not because of their being a pure bred. If that were true, there would not be the ancient breeds among us today, and there are quite a few. It's what man does to a breed, once established, that determines its fate.
You suggest that inbreeding would be the downfall of any breed. That just isn't true. It's the breeding of individuals with health defects or being carriers of that defect that can wreak havoc on a breed. One of the healthiest groups of dogs are the seeing eye dogs bred in Morristown, N.J. and they have one of the highest breeding co-efficients (rate of in-breeding) among any group of dogs. It goes to show that it's intelligent breeding and not simply avoiding in-breeding that affects the overall health of a group of dogs.
Most will say that a reputable breeder will adhere to the breed standard and will breed for that standard. That's great, except that there are some breeds that have had the standard changed to the point where breeding to the standard will produce a dog with problems. This has occurred in the GSD, Cavalier King Charles Spaniel and the flat faced dogs, among others. Philosophically speaking, I'm not sure you can breed to the modern show standard and be responsible with those breeds. As you probably know, some of these breeds' standards are up for review by the Kennel Club due to the inherent health problems associated with the standard.
While the Yorkshire Terrier does have its share of health problems, it is not due to the breed standard. There is a large enough gene pool to draw from so breed vitality isn't an issue. I feel the various YT breed clubs have been good stewards of the breed and I don't see the breed being threatened so long as those breeding adhere to the standard and ensure they only use healthy dogs as breeding stock. |