Also called acral lick dermatitis, this is a frustrating skin condition caused by compulsive, relentless licking of a single area — most often on the front of the lower leg. (pets.webmd.com)
Veterinarians diagnose acral lick granuloma through a careful examination of the lesion, the pet's history, age and a thorough physical exam. (2ndchance.info)
Note that a dog may also lick the paws due to a foreign object in the paw or a condition called acral lick dermatitis. (dog-health-guide.org)