I don't know if anyone is still going to read this or not, but I got a little more information on this topic from both my Bio I and Bio II professor and my Lab Professor.
My professor that I have now, my Bio II professor, his field is genetics. I asked him after class one day about if purebreds were necessarily sicklier than other "mutts." He himself has a purebred with health problems. We talked about a thing called "true breeding" which is generally an easy concept to grasp. It's the breeding of homozygous dominant or homozygous recessive alleles, in this case, dogs - dogs with the same type of alleles(alleles, because all dogs have the same genes) bred with another type of dog with the same alleles. This will sometimes bring out recessive alleles that would have normally remained unexpressed, but when mated with another dog with those same recessive alleles, you get a dog expressing that recessive trait. Now sometimes that recessive trait isn't bad. For example, the allele for six fingers is a dominant trait, but MOST humans have only five on one hand, a recessive trait. But sometimes that recessive trait IS bad, as in the cases with some dog's health problems. Mating different breeds of dogs is good, because you are mixing different alleles, keeping the dominant traits expressed most of the time. Purebreds don't necessarily have to be unhealthy; the breeder can preform tests on the dogs to see what traits they have, etc. But even then it's hard to produce a dog with ALL the desirable traits we want.
Does any of that make sense? LOL.
