Cause
The causes of acral lick granulomas include infections caused by bacteria, fungi, or mites; allergies, cancer, joint disease, or previous trauma; and an obsessive-compulsive disorder caused in some dogs by boredom. Dogs are incited by their condition to lick an area until they cause hair loss and erosion of the superficial skin layers. The consequence is further itching, which in turn results in more licking. This itch-lick cycle is exacerbated by the fact that damaged cells release endorphins, or brain chemicals, that are powerful analgesics. The licking may with time cause secondary infections, thickening of the skin, and changes in pigmentation.