https://www.alternet.org/books/heres-why-breeding-dogs-amounts-animal-cruelty
Why do cats live longer than dogs? And why are most cats free of the bone deformities, respiratory problems, and other serious deficiencies found in dogs? The answer is that cats choose their own mates. Or most of them did until it became important to spay or neuter cats, partly because the shelters became overcrowded with unwanted cats who had to be euthanized to make space for more unwanted cats, and partly because the feral cat populations were mostly successful, thus too many cats were outdoors killing birds.
Choosing one’s mate is the best way of breeding by far, and mostly it’s up to the females. Yes, males come sniffing around as interested suitors, but females choose whom to accept. We humans do this, dogs once did it, and cats still do it if they can, choosing strength, good health, and high status.
Dog breeders have different agendas, encouraged by the various kennel clubs and dog-show providers to produce animals who are grossly distorted and seldom live as long as dogs bred for other purposes. As for me, I had dogs who were not spayed or neutered, and two of them, both Siberian huskies, produced three puppies so fit and healthy that as young adults they won just about everything there was to win in the New Hampshire three-dog races. Other contenders hated to see them coming.
All my huskies were fabulous as racing dogs. We have an attic full of trophies to prove it. They lived in good health to old ages, and if they’d had to live in the woods, they’d have made it on their own without a problem.
I’m not saying that every dog should be physically capable of living in the wild, although that’s not a bad thing. I’m just saying they’re better off without respiratory problems or hip dysplasia. And why do they have such problems? As has been said, they’re bred to meet certain standards that allegedly include good behavior but overwhelmingly are for various forms of unnatural appearance as determined not by other dogs but by kennel clubs—here in the United States it’s the American Kennel Club (AKC)—that issue the standards to breeders. For all the lip service offered by these kennel clubs about behavior, we ignore the fact that for dog breeds, behavioral similarities are minimal and individual differences are great, and when we accept the kennel club standards we say good-bye to strong dogs with good health and high status.
more at
https://www.alternet.org/books/heres-why-breeding-dogs-amounts-animal-cruelty 
