Bear in mind dogs are pretty unnatural creatures at this point - we've done so much breeding that you can't really assume any natural forces apply to their deve

Bear in mind dogs are pretty unnatural creatures at this point - we've done so much breeding that you can't really assume any natural forces apply to their development at this point. After all, why would any creature develop a facial structure that makes it hard to breathe (like bulldogs, pugs, etc.)? The answer is because humans are selfish.