Even if pitbulls are singled out due to social reasons, how does that invalidate its biology? People have bred dogs for a multitude of reasons, from fighting to farming to hunting. If bulldogs can hardly breathe due to centuries of inbreeding, why wouldn't some dogs be affected in other areas (physical strength or behavior) if humans kept pushing them in a certain direction? You can punt a chihuahua across the room and it'll run away, but most sane people wouldn't mess with dogs like german sheperds, pitbulls, mastiffs, etc. because they will kill you lol. As such, people generally don't use chihuahuas for anything that involves a prolonged fight or confrontation because they can't do anything but yap

These days shit like human eugenics is frowned upon. You can easily refute the conflations between dog breeding and human behavior - and even when there is a "parallel", you can easily point to all the monarchs who ended up like these dogs from their royal "selective breeding", though that's probably not productive because fascists want to euthanize disabled people even if they are the result of their "master race" eugenics projects.