Dogs almost always have dewclaws on the inside of the front legs and occasionally also on the hind legs. Unlike front dewclaws, rear dewclaws tend to have little bone or muscle structure in most breeds.

All dogs are born with front dewclaws, says Dogster. Some dogs are also born with rear dewclaws. Unlike the dewclaws on the front leg, which are affixed to the leg by bones and ligaments, rear dewclaws are only attached by a loose piece of skin, which can make them more prone to injury.

In many breeds — but certainly not all — the dewclaw has traditionally been removed in the first few days of a dog’s life. In some breeds, the removal is thought to improve appearance for the show ring. In others, it’s done to prevent possible injuries, such as being damaged while a hunting dog works through brambles.

Because front dewclaws serve an important purpose, they should not be removed unless there is a very good reason to do so. In rare cases, a dog’s dewclaw may be severely injured or develop a disease (e.g., a cancerous tumor) and removal under those circumstances would certainly be in the dog’s best interests.

Norwegian Lundehund

Dewclaws or extra toe on the back feet of dogs are due to the genetics of certain breeds that have adapted to the environment around them. Although in some cases there is a genetic explanation, many dog breeds that have these dewclaws, are considered to have a genuine malformation, a genetic fault in the breed.

Polydactyly is a rare autosomal-recessive genetic disease characterized by additional phalanges in the fore or hindlegs of dogs. Dogs in general have four digits in the hind limb, presumably due to an evolutionary adaptation.

Unless your dog is having problems caused by the dewclaw or the extra appendages, then there is no need to do anything about them. Often the dewclaw is attached by bone or sometimes it may only be attached via skin. The great Pyrenees is the most known polydactyly canine and can even have six hind toes.

Like cats, dogs normally have five toes on their front feet and four on the rear feet. By the way, if you’re staring at your dog’s front feet and only counting four toes per foot, he’s probably had his fifth toe, commonly called the dewclaw, taken off at birth for a cleaner look or to avoid getting it caught on things.

Polydactyly (also known as canine preaxial polydactyly or PPD) refers to the restoration of the first digit in the hindlimb (known as the hind dewclaw) that was lost during canine evolution.