Lick Granuloma (Acral Lick Dermatitis or ALD) in Dogs
Lick granuloma, also kown as acral lick dermatitis (ALD), Acral Lick Granuloma (ALG) or Acral Lick Furunculosis (ALF), is a common condition observed in large, active dogs in which the dog licks an area excessively, usually on the front leg, until a raised, firm ulcerated lesion is formed. These lesions are prone to infections, which make them itchier and itchier, which then leads to a self-perpetuating cycle of itching and licking. The term “acral” refers to the peripheral portion of an extremity.
Many underlying diseases are responsible for this condition. It could be caused by psychological and behavioral factor or by skin and internal diseases. Allergies, endocrine disease, parasitic, bacterial and fungal diseases may cause lick granulomas. Interestingly, allergy to flea bites may also be a cause. Aggressive flea control is recommended in flea-sensitive individuals. In other cases, a change in the environment, a stressful situation or a change in the work schedule of the owner could be the trigger.
Sometimes the granuloma occurs in an area of a previous trauma like a fracture and that may be triggered by an abnormal sensation in the skin. In other cases, the excessive licking may be a sign of pain. Arthritis may be evident in the underlying joint.
It is important that the underlying case is identified and addressed in order to resolve this frustrating condition.
Diagnosis of Lick Granulomas in Dogs
In any case of lick granuloma, diagnosis should include deep skin scraping to rule out demodicosis and fungal culture to rule out dermatophytosis.
It is important to note that deep skin scrapings may be falsely negative in areas that are excessively fibrotic and biopsies may be necessary to rule out demodicosis.
Biopsy for histopathology and culture should also be taken to rule out fungal infections, pythiosis, neoplasia (cancer) and to identify the bacteria responsible for the infection (Pseudomonas is often present together with Staphylococcus).
Pythiosis is a potentially lethal subcutaneous fungal disease common in Southeastern United States. It is caused by an alga present in standing water and dogs become infected swimming in infected areas. It has a predilection for German shepherds and Labrador retrievers and is intensely pruritic and rapidly progressive. If the animal has a history of living in endemic areas for pythiosis, a biopsy for histopathology and culture should be taken as soon as signs compatible with a lick granuloma are observed.
Failure to make an early diagnosis may result in the animal’s death due to the fact that the only possible treatment at the present time is aggressive surgery.
Biopsy of true cases of lick granuloma reveals marked epidermal hyperplasia and dermal fibrosis. It is common to see folliculitis, or inflammation of the hair follicle, and furunculosis, which is a ruptured hair follicle, with secondary bacterial infection.
Treatment of Lick Granulomas in Dogs
As you will read – this is a complex problem with no one logical or complete cure. Many therapies are recommended, often together, to try to eliminate or minimize the problem.
A course of antibiotics should always be prescribed to treat the concurrent infection. Marked decrease of pruritus is seen in most cases after antibiotic therapy. As this is a deep infection, antibiotics should be continued for at least two months. Some cases have a mixed bacterial infection, so therapy should be based on culture and sensitivity. Good empirical choices include cephalosporin (cephalexin) and fluoroquinolone (enrofloxacin). As a general rule antibiotic therapy should be continued for a month past resolution of clinical signs. It is not uncommon for an antibiotics course to be at least 4 months.
It is very important to try to identify the possible underlying disease for lick granulomas, as there is usually a cause. Veterinarians reserve symptomatic treatment for only truly idiopathic cases.
Your veterinarian will want to spend time with you and identify any possible factor that might have triggered the condition, including the presence of a new dog, cat or baby in the house, a change in work schedule, death of another pet in the house.
Special effort should be made to correct any possible stressful factor and change the lifestyle of the animal so that more time is spent exercising and playing.
Immunotherapy to address allergies may be recommended. Drug therapy using cyclosporine (Atopic®) has been beneficial in some dogs.
Several drugs can be used for the symptomatic therapy for lick granulomas. They should be used only for a short period of time to break the cycle. They include drugs like clomipramine and fluoxetine.
More Options for Treating Lick Granulomas
Topical therapy may help in some cases. Mechanical barriers such as socks, bandages, or Elizabethan collars are sometimes useful to minimize exposure to the area.
Topical medications or liquids to act as a deterrent are used such as Yuk® Anti-lick Gel, Bitter Yuk!, Grannick’s Bitter Apple or Grannick’s Bitter Apple + Liquid Heat.
Capsaicin (0.25 percent) works by triggering the release of Substance P (a neuropeptide involved in the transmission of pain and itch). After repetitive use the skin is depleted of Substance P thus itch and pain are not perceived any longer. It could be applied alone or in combination with other compounds like Bitter Apple® to create a bad taste. It should be applied twice or three times daily at the beginning of the treatment. Frequency of administration may be increased once improvement is obtained.
Capsaicin is available over the counter. Initial and temporary worsening may be seen in some cases. The product should not be applied on ulcerated areas but around the lick granuloma to avoid a burning sensation. Sensitization may occur with prolonged used. Relief persists for several weeks after discontinuation of therapy as it takes several weeks to replenish the storage of Substance P in the skin.
A combination of fluorinated steroids (e.g. Synotic®) and flunixin meglumine (Banamine®) may also be helpful. Solution should be applied twice daily initially until healing is observed. Intralesional injections of glucocorticoids (Vetalog®) (Depo-Medrol®) may be useful in small early lesions but are usually without any benefit in more chronic and ulcerated lesions.
Cryotherapy, radiation therapy, and surgical removal are last resort options that could be attempted if everything else has failed.
Because of the possible boredom component to this disease, it is a good idea for dogs with this disease to also have daily play and exercise. Socialization and play with other dogs is sometimes beneficial. Providing both individual and group attention in multi-dog homes is important.
Follow-Up for Lick Granulomas in Dogs
Boredom can be prevented by allowing plenty of exercise, especially in large breed dogs. Once lick granuloma has started, aggressive antibiotic therapy is recommended. In some cases this condition is related to flea allergy, thus flea control may prevent this condition.