What are the reasons for a dogs ability to smell

Dogs can detect cancer cells, explosives, drugs, and track and find lost people or animals - all by using the power of their noses and the part of their brain that analyses and processes those scents.

this is what i looked up and got

fumikage isn't really a bird, and tsuyu does have teeth. tsuyu has a transformation quirk which still allows her to be partially human. otherwise we'd have a large frog running around. fumikage has teeth because again, he isn't a bird. his head was a quirk mixture if i'm correct.