Acral Lick Dermatitis (Lick Granuloma) in an Adult Male Labrador Retriever Dog

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Introduction
Acral lick dermatitis (ALD), also called lick granuloma, is a common, self-inflicted skin disorder with a focal lesion usually found occurring on the distal (acral) extremities of the limbs 1 . The common site for excessive compulsive licking is usually on the anterior carpal or metatarsal skin. Male dogs of larger breeds are commonly affected. Initially, the lesion appears small and gradually increases in size with expanded licking. Later, alopecia develops, and the lesions become firm, raised, thickened, and plaque leading to nodular ulceration, fibrosis, and hyperpigmentation 2 . Continuous licking also leads to secondary infections like deep pyoderma and furunculosis. The etiology is usually multifactorial 3 with an underlying psychological factor. The possible reasons are loneliness, confinement for a long period, a female dog in heat nearby, a death in the family, and the moved apart of children or members of the family. Other causes include tumors, infection, trauma, and orthopedic problems 2 . Histopathological findings are supportive in confirming the diagnosis, including epidermal hyperplasia with marked rete ridge formation, and compact orthokeratosis hyperkeratosis, which strongly suggests chronic surface irritation and fibrosis of the dermal papillae 4 . Treatment includes behavior-modifying drugs, such as anxiolytics (alprazolam, diazepam, and lorazepam), tricyclic antidepressants (fluoxetine, amitriptyline, imipramine, and clomipramine), endorphin blocker (Naltrexone) and endorphin substitute (hydrocodone) medications, and acupuncture therapy 5. This article described a case of Acral Lick Dermatitis (ALD) and its successful management.

Case report
A five-year-old male Labrador retriever dog was referred to Small Animal Medicine Unit, Veterinary Clinical Complex, Rajiv Gandhi Institute of Veterinary Education and Research, Puducherry, India, with a history of a wound on the metatarsal region with bleeding which started as a crust-like lesion and then increased gradually on continuous licking. The lesion was painful on touch and hence reduced its exercise time. On clinical examination, the dog was active, popliteal lymph nodes were palpable, mucous membrane was pink, and the rectal temperature was 101.7°F (38.7°C). The lesion on the metatarsal region of the right hind limb was firm, raised, nodular, and erythematous ( Figure 1). Other skin diseases caused by parasites (such as Demodex, Sarcoptes) and fungal organisms were ruled out by skin scraping examinations (deep skin scraping, direct microscopic examination). An impression smear was taken, and gram staining was done. There was no evidence of gram-negative and gram-positive bacterial organisms. The dog did not show any signs of orthopedic problems. Based on the history, clinical signs and other dermatological examinations, the skin lesion was diagnosed for acral lick dermatitis.
The case was diagnosed as ALD without any secondary infections and was treated with topical glucocorticoid ointment of Triamcinolone acetonide 0.1 % (TRIAMADERM TM , Nulife Pharmaceuticals, India), and bandaging was done on the lesion to prevent further trauma. Besides, the owner had been advised to apply Elizabethan collar (E-collar) constantly and increase the play time and exercise with the dog to overcome the obsessive-compulsive disorder. After 15 days of application of the ointment and wearing E -collar, the erythema and swelling reduced ( Figure 2). After 6 weeks, the animals showed complete healing, and hair growth was also noticed (Figure 3).

Discussion
Acral lick dermatitis is an obsessive-compulsive behavior in dogs due to boredom. It is a skin lesion characterized by continuous licking resulting in raised, thickened, ulcerative plaques mostly affecting the lower extremities of dogs 3 . Middle-aged to older breeds like the Doberman, Great Dane, Golden retriever, Labrador retriever, German shepherd, and Boxers are usually involeved 4 . Dogs are impelled by their condition to lick a region until they cause hair loss and erosion of superficial skin layers. The outcome triggers an itching sensation, leading to more licking. This itch-lick cycle is exacerbated by the way that damaged cells result in releasing endorphins, or brain chemicals, that are powerful analgesics 6 . Diagnosis is usually by the history and typical appearance of a wound in the foot region. In this present case, Triamaderm™ (Triamcinolone acetonide, Nulife Pharmaceuticals, India) reduced the erythema, nodular size, and swelling and showed complete healing in 6 weeks. Triamcinolone is a highly potent synthetic glucocorticoid with a half-life of 12-36 hours and a powerful steroid used to treat swelling and itchiness. Triamcinolone is a highly effective anti-inflammatory agent for dogs and cats, exhibiting fewer sodium-retaining effects while providing better anti-inflammatory effects compared to other corticosteroids 7 .

Conclusion
Acral lick dermatitis is usually diagnosed based on the history, clinical signs, and behavior of the dogs. Most dogs require treatment for inflammation, infection, and psychological components. Topical and oral medications like corticosteroids are generally used for inflammation. In case of secondary skin infection, antibiotics are used. Behavior-modifying drugs can be used to overcome obsessive-compulsive behaviors. Management practices like increasing the playtime with the dogs and exercise have been shown to increase recovery.

Competing interest
The authors declared that they have no conflict of interest.

Authors' contribution
Abiramy Prabavathy Arumugam diagnosed the case. Devadharshini Kamalakannan, Vanmathi Arulselvam, and Devadevi Narayanan conducted the treatment. Vijayalakshmi Padmanadan supervised the whole procedure. All authors read and approved the final version of the manuscript for publication in the present journal.

Funding
The authors received no financial support for this article's authorship and/or publication.

Ethical considerations
The authors confirm that all the named authors have read and approved the manuscript. All authors consented to publish this article and confirm that there is no plagiarized information in the article. All sentences are written originally, and all available data are published in this article.