Not necessarily? More like by default. Purebreds are a thing because of certain genetic traits and are bred to not only maintain them, but to enhance those traits. Because of all that inbreeding the propensity for certain diseases and cancers are vastly increased. A purebred dog or cat will with near certainty be riddled with cancer or disease by the time they start getting a bit older. I love both cats and dogs, but purebreds shouldn’t be a thing.
It’s the size of the population and the competence/goals of the breeders. Breeders chasing exaggerated traits at the expense of the animal’s health are the major problem.
There are “pure” breeds of every domestic animal that are healthy – provided it’s a line not perpetuated by selfish idiots. Domestic shorthair cats, various working breeds of dogs, horses, etc.
I like how you put “pure” in quotes because the way they keep those lines healthy is by occasionally mixing in other breeds.
