Dog Dewclaws: What Are They?

Have you ever noticed that extra nail on the side of your dog's paw? It might look like a sort of "dog thumb." That's called a dewclaw, and it's a remnant of the evolutionary past of your family pet.

Why Do Dogs Have Dewclaws?

Psychology Today author Dr. Stanley Coren traces your dog's dewclaw back 40 million years to "a tree climbing cat-like animal known as miacis which was an early ancestor of our modern dogs," he says.

"Obviously if you climb trees having five toes is an advantage. However, miacis eventually evolved into the ground dwelling species cynodictus. From this point on, successive generations of the animals that would become our dogs began to become specialized as social hunters," Dr. Coren writes.

That means the extra nail serves little purpose for today's pups. Despite that, most dog breeds still have them on their front paws. Some breeds, like the Great Pyrenees and Briards, have rear dewclaws or can have double dewclaws — called polydactyly.

While they are considered to be of little use, they are certainly not completely useless. Dogs can use them for grip. Most commonly you might see your pup gripping a bone with the help of his "thumb." A dog breed that uses his "thumbs" is a Norwegian lundehund that uses them to help him scale mountains, according to the American Kennel Club (AKC).

The Dewclaw Debate

The AKC, however, notes that, for most dogs, the appendage is "essentially an extra paw" and "serves virtually no purpose" for most dogs.

Because of that and because some dogs are prone to getting them caught or torn — which can cause a dog extreme pain and risk infection — the AKC calls dewclaw removal one of the "safe and standard animal husbandry practices designed to protect the safety and welfare of dogs."

The AKC calls for the appendages to be removed shortly after birth. In fact, many dog breeders have the surgery done in his first days of life. That means if your dog doesn't have dewclaws, they might have been removed before you even took ownership of your pup.

But other organizations strongly believe that removing dewclaws serves little purpose and causes great pain to the animal. Because of that, some — like The Kennel Club in the UK — have restrictions on when dewclaw removal can be done.

"Beyond the risk of the dewclaw getting caught on things, there is no benefit to removing them," Albuquerque Vetco says. "It can also be a painful procedure for your dog."

Vets at the New Mexico clinic recommend owners keep the nail of the appendage trimmed short to help prevent it from catching and potentially tearing. Whatever you decide to do with your dog's dewclaw, you should consider keeping all of his claws trimmed. Unlike his ancestors or canine cousins in the wild, dog claws don't serve as great of an evolutionary need as they aren't necessary for hunting prey. After all, your lovable pup would much rather you feed him a nutritious meal than have to go hunt for his own.

The debate continues, but your dog certainly doesn't know that. All he cares about — whether he has his extra claw or not — is that he surely has full grasp on your heart.