Have you ever looked at your dog's lower legs and wondered why there's a very thumb-like nub there?
You know that you have thumbs because radios have knobs. But dogs are hopeless at finding a station that doesn't play Britney Spears all the time. So why do dogs have thumbs, anyway?
Dog thumbs are called "dewclaws‚" and most dogs have one dewclaw on each of their legs. These dewclaws are generally believed to be vestigial, meaning that they've ceased to have any function-they're just useless bits of skin. However, because polydactility-having more than one dewclaw per leg-is common to breeds that traditionally climb a lot of mountains, herd a lot of sheep, or spend a lot of time in the snow, the supposition is that in the past the toes helped working dogs keep their balance and grip over uneven surfaces.
And though operationally useless, dewclaws do have one recognized value: at dog shows, the number of toes a dog has is very important. Great Pyrenees, for example, should have double hind dewclaws to compete in American Kennel Club shows. Some other breeds, like the Rottweiler, may or may not have dewclaws, and other breeds still, like the Weimaranar, can have no dewclaws at all; their dewclaws must be removed to compete in AKC shows.
Pet dogs may also have their dewclaws removed, though more for safety than aesthetics.
"Dewclaws get stuck on things," says Dr. Diane Levitan, a Long Island, N.Y., veterinarian. "They can tear and get infected."
Dewclaw removal takes place when a puppy is only a few days old, before bones are ossified. Vets use sterile scissors to remove dewclaws, while at-home removals may rely on scissors or teeth-people's teeth, that is. Puppies are said not to mind having their dewclaws bitten off any more than having them snipped, but for the people it's an acquired taste.
