During the last photo shoot, a human model with a mower stood in one location of our yard for several hours while the photographer captured the image from several light angles. Our home is on a street that many parents use as a cut through to the back entrance of a local elementary school. After one day of extensive photography, one parent (who happens to be a Creature Comforts Client) noted she knew that we were quite devoted to our gardening hobby, but she had never seen anyone remain in the same place mowing for over 4 hours! Witnessing this after going up and down the street that day while running her daily errands, the next day she commented about the mowing tractor, “It's still there!”
Sometimes things stay and are noticed. And other times, they just blend into the background and go unnoticed until someone points them out. It's the same in the veterinary world, and today we'll discuss one such thing: acral lick granulomas (Skin lesions that seem to remain forever).
What are canine acral lick granulomas of the skin?
Acral lick dermatitis (lick granuloma) is a lesion induced by chronic licking, most often on the top of the wrist up to the elbow, as well as on the back hock (ankle). It is more common in large breeds of dogs, but can be seen in any breed of dog. Common causes are intense itching, pain, and obsessive desire to lick (suggesting a behavioral component). Review of the history and a good examination are necessary to consider an underlying allergic component.
What are the concurrent signs and how is it diagnosed?
Many patients, licking the area will have a past or current history of skin or ear infections and itching in many areas of the body. This disorder has a classically thickened area of the skin in the wrist (carpus) or ankle (hock) area with hair loss, ulceration, and thickened skin. Since pain associated with trauma, arthritis, prior fractures, tumors, surgery sites, deep infections, and peripheral nerve pain will also cause compulsive licking, in many cases a more in-depth work-up will be required for complicated or reoccurring cases.
How is it diagnosed since many conditions seem similar?
Besides the traditional testing for infections (skin scraping for mange mites, bacterial and yeast cytology, ring worm culture, bacterial cultures), in many cases a skin biopsy and a radiograph of the area to check for bone damage maybe indicated. Allergy testing for specific environmental allergies and a food trial maybe indicated. Left untreated, secondary problems such as deep bacterial infections and ruptured oil glands can perpetuate the cycle of licking/itching and must be addressed. Good insect control for fleas, ticks, and mosquitoes is essential. Statistically, 25% of these lesions are resistant to traditional antibiotic therapy, so once again bacterial culture is important!
Can a dog have a primary obsessive/compulsive disorder as the only cause of this skin lesion?
Although it is possible there is a primary behavioral disorder, there are usually concurrent causes for the licking, as mentioned above. However, the licking behavior can become the overwhelming factor.
Why is a diagnosis important?
If the cause of the itching is not addressed the lesion will typically return even after resolution of the signs.
Why do bacterial infections need to be addressed in the long term?
It is estimated greater than 90% have deep bacterial infections in the skin lesions. These infections tend to be “walled off” and thus difficult for short courses of antibiotics to effectively reach and control. An average of 4 to 8 weeks or longer is needed with the goal being to treat at least 1 week longer than normal findings of the skin lesion including some hair regrowth and resolution of the superficial skin infection.
Why are steroids (glucocorticoids) concurrently used with antibiotics in treatment regimens?
They relieve inflammation, itching, and alleviate suffering of the ingrown hairs and subsequent oil plugs that develop.
One complaint is the licking is 24/7. Any suggestions?
It may be necessary to apply physical restraints such as an Elizabethan or BiteNot collar along with a bandage on the area. Once there are signs of improvement, the restraint maybe removed for limited periods of time when supervised. Realistically, this can be an 8 to 12 week period of treatment.
Is there any topical medicine for these skin wounds?
Besides washing with antibacterial soap, topical preparations containing antibiotics (example mupirocin cream), steroids (genesis spray), and often DMSO (synotic) are indicated in some combination therapy. Bitter apple and other anti-licking products are helpful for some patients.
What about anti- anxiety medication orally and increase in exercise?
Tricyclic anti-depressants such as clomicalm or Elavil, and Selective serotonin reuptake inhibitors such as Prozac are helpful to cut the compulsive licking. In addition, a doubling of the exercise program to enrich the environment/lower stress and thundershirts will help in many cases.
I have seen these skin lesions on the Lower joints of dogs and they are often hairless 6 months later. Are there any alternative treatments?
Many patients have extensive scar tissue that will never grow hair. In some cases a CO2 laser is utilized but the results have been mixed. Other patients, in spite of in-depth work ups for concurrent illness, need to continue to wear an Elizabethan collar when unsupervised. Sadly, in many cases “it’s still there”.
Betsy Sigmon DVM
Hospital Director, Creature Comforts Animal Hospital
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