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.
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.