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By T. J. Dunn, Jr., DVM
Everyone who has had a dog with a lick granuloma will tell the same story. The skin lesion started as a tiny sore spot on the skin and the dog kept licking at it. Applying medications didn't seem to help much and the darn thing kept spreading outward while thickening. It often would be wet and oozing from the dog licking and chewing incessantly at it. Finally a trip to the veterinarian revealed a name for this patch of thickened, scarred and irritated skin: ACRAL LICK GRANULOMA! "Well, OK", the owner would say, "so what do we do about it?"
The problem is that we veterinarians cannot give the owner a specific recipe for a cure for acral lick granuloma. The skin is so deeply affected that even down to the base layer of the skin there can be found under the microscope little pockets of bacteria, broken hair follicles, plugged and scarred oil glands and dilated and inflamed capillaries. And if these skin lesions are removed surgically, the dog simply licks at the sutures or incision line after the surgery heals, thus creating a brand new granuloma right where the original one was!
ac·ral adj. Of, relating to, or affecting peripheral parts, such as limbs, fingers, or ears
The photos above are of an Airedale with a classic case of acral lick granuloma. (Click on the photos to see a larger version in a new window.) The dog is perfectly healthy, is on an excellent diet, does not suffer from allergies but does have slight separation anxiety when his owner leaves for work.
In this case the "cause" of the licking specifically at the affected area of skin may be self stimulation to help allay the anxiety of separation from the owner. The skin lesions will heal slightly, almost seem like they are going to heal, and overnight (or during the day while left alone) the lick granuloma is activated, licked raw from continuous passes of the tongue.
Also with this dog, when one of the attempts to break the cycle of licking involved wrapping the lower leg with a cast to keep the dog away from the lesion, he began to make a new one in the same location on the opposite leg! Now there are TWO LICK GRANULOMAS!
This airedale isn't alone, however. No, there are certain breeds that appear to be more prone to acral lick granulomas, including the Doberman Pinscher, German Shepherd, Golden Retriever, Labrador Retriever, Irish Setter and Weimaraner.
There are numerous theories and one may apply for one dog and an entirely different theory may be correct for another. Take your pick:
1. Many dermatologists think that boredom is a major underlying factor in some cases of Acral Lick Granuloma. The dog's licking activity helps pass the time.
2. Some believe that allergic inhalant dermatitis creates stress in the skin resulting in inflammation and pruritus (itching) which triggers the dog's propensity to lick at any convenient area.
3. A foreign body such as a thistle spine, splinter or bee sting might start up a reaction in the skin which leads to drawing the dog's attention to the spot.
4. Bone or joint pain can draw the dog's attention to the wrist or ankle area and in an attempt to alleviate the discomfort the dog licks over the top of the joint.
5. Psychological stimuli such as separation anxiety, a new pet or child in the home, or neighbor dogs invading the dog's "territory" can create psychological stress. Self stimulation such as picking out an area to concentrate on and licking for extended periods of time are a way for the dog to relieve the "stress".
6. Hypothyroidism has played a role in some cases of acral lick granuloma, especially in Black Labs.