They can be, respectable breeders will usually do it outside of their dog’s own gene pool (mating them with another owner’s dog that has the same desired qualities), but there are definitely breeders that keep it within the gene pool in order to maximize the desired genes being expressed.
To be fair, there’s some stuff that was bred into the gene pool near the inception of the breed that can’t be easily removed now. You can reduce the risk by avoiding incest and thorough genetic testing where possible, but there’s some health issues that would plague purebreds for a long time even if every breeder in the world was responsible.
They can be, respectable breeders will usually do it outside of their dog’s own gene pool (mating them with another owner’s dog that has the same desired qualities), but there are definitely breeders that keep it within the gene pool in order to maximize the desired genes being expressed.
To be fair, there’s some stuff that was bred into the gene pool near the inception of the breed that can’t be easily removed now. You can reduce the risk by avoiding incest and thorough genetic testing where possible, but there’s some health issues that would plague purebreds for a long time even if every breeder in the world was responsible.