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. Sometimes some dogs will even have more than one dewclaw on the same foot; often at least one of these dewclaws will be poorly connected to the leg and in this case it is often surgically removed. When a dog has extra dewclaws in addition to the usual one on each front leg, the dog is said to be "double dewclawed". There is some debate about whether a dewclaw helps dogs to gain traction when they run because, in some dogs, the dewclaw makes contact when they are running and the nail on the dewclaw often wears down in the same way that the nails on their other toes do, from contact with the ground. However, in many dogs the dewclaws never make contact with the ground; in this case, the dewclaw's nail never wears away, and it is then often trimmed to keep it to a safe length.
The dewclaws are not dead appendages. They can be used to lightly grip bones and other items that dogs hold with the paws. However, in some dogs these claws may not appear to be connected to the leg at all except by a flap of skin; in such dogs the claws do not have a use for gripping as the claw can easily fold or turn.
Excerpt from http://en.wikipedia.org/wiki/Dewclaw further information and photographs also on this link.
The dewclaws are not dead appendages. They can be used to lightly grip bones and other items that dogs hold with the paws. However, in some dogs these claws may not appear to be connected to the leg at all except by a flap of skin; in such dogs the claws do not have a use for gripping as the claw can easily fold or turn.
Excerpt from http://en.wikipedia.org/wiki/Dewclaw further information and photographs also on this link.
