I agree, backyard breeding and ownership have their toll. Almost every chihuahua I see (including pedigrees) shake terribly. That's a sign of nervousness being bred into them over and over. I will be the first to admit I am bias, but when I walk into an animal shelter there are more apbt's than any other specific breed. I am barked and growled at by mutts and pure breds alike, but rarely am I barked at by an apbt. Sadly, a lot of people buy the breed because to them its a status symbol and are so quick to give them up when they don't turn out properly trained.