Dewclaw

n. small useless claw (of dogs); hoof separated into two sections (of deer, hogs, etc.)

A dewclaw is a vestigial digit of the paw of many mammals, birds, and reptiles (including some extinct orders, like certain theropods). It grows higher on the leg so that in digitigrade species, when the animal is standing, it does not make contact with the ground.
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(n.)
In any animal, esp. of the Herbivora, a rudimentary claw or small hoof not reaching the ground.
  

A digit, sometimes called the fifth claw, located high on the inner side of a dog's front and hind paws.

dewclaw
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