Dogs like to lick. They'll lick you, the floor under your table and anything else emitting an enticing scent. Your dog's licking is obsessive or compulsive if it has no sensible trigger like the presence of food, if it's highly repetitive or unnaturally sustained or if your dog can't be interrupted while she's at it.
Go to the Vet
The first course of action for treating your dog's obsessive licking is to go in for a veterinary checkup to rule out medical causes. Parasites, allergies, skin infections, hormonal imbalances, localized pain and cognitive dysfunction are all potential problems causing the OCD behavior. Obviously, diagnosis is important to your pet's well-being and targeted treatment is the way to clear up symptoms, including the obsessive licking. In addition, if your dog is obsessively licking herself, your vet can check for lick granulomas, dangerous and painful sores that can develop from repeated licking.
Don't Reinforce the Behavior
You may be inadvertently reinforcing your dog's obsessive licking. If she licks people excessively and you take it for affection, you probably praise her, pet her and bestow affection on her in return. This sends the message that her licking is good and will earn her rewards. Alternatively, if your dog obsessively licks items or surfaces and you or others in your home think it's funny, you may be laughing and otherwise offering increased attention in response to the behavior. This too only serves to spur it on.
Your dog's obsessive licking may very well result from boredom, so provide more attention and stimulation. If you leave her crated, shut away in a room or alone outside for significant periods, stop. Play with your pet more, take her for more walks and take her out to different places. Increase her daily exercise and supply puzzle toys and other entertaining items for when she's on her own. Consider signing her up for a doggy daycare or some sort of canine class in your area for variety and more socialization, especially if you're short on time for her. Arrange for a dog walker or dog sitter if necessary.
Obsessive behaviors, including licking, often come about from stress and anxiety. This is particularly likely if your dog wasn't properly socialized as a puppy. Work on socialization to build up your pet's adaptability and resistance to stress; doggy daycare and other programs provide good opportunities, as do trips to the dog park or play dates with a friend or family member's dog. Schedules and routines are important for a dog's mental health, so stick to them, and positive reinforcement-based training also provides much-needed structure. Try dog-appeasing pheromone or canine aromatherapy products to calm your pet when there's noise, visitors or other environmental stimuli that may be stressful. Talk to your vet about anti-anxiety medications and supplements, too.