22 DERMATOLOGY VP DECEMBER 2016 ACRAL LICK DERMATITIS (ACRAL LICK GRANULOMA, LICK GRANULOMA) ACRAL LICK DERMATITIS  Trauma. not accessible to the dog. REFERS TO A SELF-INFLICTED  Foreign body reaction.  A new dog has come to the FOCAL LESION usually found  Deep pyoderma. neighbourhood. occurring on a distal (acral) extremity.  Pododemodicosis.  A death has occurred in the family. Favoured sites for the excessive  Hypothyroidism.  A long-time companion of the dog compulsive licking, which produces  Neuropathy. has died. Figure 3. A chronic lesion of acral the lesion, are most commonly on the  Osteopathy.  Children or other members of the lick dermatitis in a crossbreed anterior carpal or metatarsal skin.  Arthritis. family have moved away. dog. There is ulceration, The problem tends to occur in hyperpigmentation and fibrosis. middle-aged to older breeds such as The lesion had been in existence for Underlying factors Diagnosis four months. the Doberman, Great Dane, Golden In addition to the diseases listed in the  The history (breed predisposition, Labrador, Labrador retriever, German differential diagnosis, many authorities licking) and clinical findings are very six months in severe cases (Hnilica, shepherd and suggest that a suggestive. 2011). The predominant pathogen is Boxer, although it DAVID GRANT major component  Investigation of underlying causes Staphylococcus pseudintermedius with some may occur in other in acral lick listed under differential diagnosis. strains having methicillin resistance breeds including continues his dermatitis is  Biopsy for histopathological (Schumacher and others, 2008). crossbreeds. series looking at psychological. examination. Biopsy may also be used Systemic therapy is continued until dermatological One specialist for bacterial culture as secondary the lesion clears and an assessment Clinical conditions states that infection is likely to be deep. In these is then made as to whether licking features although cases, sterile preparation of the surface remains a problem. Some cases will  Initially the lesion, in one of the environmental stress may be a is required. clear up with long-term antimicrobial sites mentioned, tends to be quite factor, other causes are usually more  Histopathological findings are therapy without relapsing. In those small but with increased licking slowly important (Hnilica, 2011) and these are often helpful in confirming the that don’t, further investigations will be enlarges. listed under the differential diagnosis. diagnosis if doubt exists. Findings necessary preferably in association with  If untreated the lesion passes It is suggested that differential include epidermal hyperplasia with a behavioural specialist. through various stages (Hnilica, 2011). diagnosis rule-outs are investigated marked rete ridge formation, compact  Surgical removal of the lesion is Alopecia develops and the lesion before considering psychogenic orthokeratotic hyperkeratosis, which possible with small lesions, but there becomes firm, raised, thickened and underlying causes. strongly suggests chronic surface is a considerable risk of the dog plaque-like (Figures 1 and 2). Later An additional complication is irritation, and fibrosis of the dermal traumatising the wound and making the there is nodular ulceration, fibrosis that even if the original cause is papillae. situation much worse. It is generally not and hyperpigmentation (Figure 3). psychogenic, secondary infection is The orientation of the collagen recommended. Secondary infection at the later stage is very common and will need to be is perpendicular to the skin surface, very common and is a deep pyoderma. treated before further evaluation. The though not to the basement membrane Treatment with behaviour- Untreated cases may progress to list of possible psychological causes (Yager and Wilcock, 1994). modifying drugs furunculosis. cited here has not changed from that Preferably, in those cases with identified  Damage to hair shafts due to the in previous editions of a standard text Clinical management stress factors, behavioural therapy is the licking may penetrate into the dermis in the last 20 years or so of previous The treatment of the lesion will depend optimal approach. Behaviour-modifying and will accentuate the deep pyoderma. editions. on how long it has been present and drugs may be of short-term use in In one study, deep pyoderma was what stage has been reached. conjunction with these cases and if no present in 94% of acral lick lesions Possible psychological Acral lick dermatitis has obvious underlying psychological cause (Shumaker and others, 2008). factors multifactorial causes and some aspects is found may be useful as stand-alone  Whatever the initiating cause, the (Miller, Griffin and Campbell, 2013) are still poorly understood. As a result treatment. There are a number of drugs problem can quickly become self-  The dog is left alone all day. many treatments have been advocated. reported to be of benefit (Hnilica, perpetuating with the development of  The dog is confined for long periods In more advanced cases a collaboration 2011). an itch-lick cycle. to a crate, kennel, cage or run. between dermatology and behavioural  Anxiolytics (phenobarbital, diazepam,  There is a new pet in the home. specialists is more likely to be effective hydroxyzine). Differential diagnosis  A female dog is in heat nearby but than individual specialists alone.  Tricyclic antidepressants (Hnilica, 2011) (fluoxetine, amitriptyline, imipramine,  Atopic dermatitis. For early mild lesions clomipramine).  Food hypersensitivity.  Topical glucocorticoids and  Endorphin blocker (naltrexone). bandaging to prevent further trauma.  Endorphin substitute (hydrocodone). This is often not successful. Licking elsewhere while a bandage is protecting References and further reading the lesion tends to suggest an Hnilica, K. A. Small Animal Dermatology: A unresolved underlying psychological Color Atlas and Therapeutic Guide; pp189-191. problem, however. Elsevier, 2011. Miller, W. H., Griffin, C. E. and Campbell,  Sub-lesional injections of K. L. Muller & Kirk’s Small Animal glucocorticoids may break the itch- Dermatology; pp650-653. Elsevier, 2013. lick cycle, but should not be used in Shumaker, A. K. and others (2008) more chronic cases where secondary Microbiological and histopathological pyoderma is a likely complication. features of canine acral lick dermatitis. Figure 2. A more advanced lesion Veterinary Dermatology 19 (5): 288-298. Figure 1. An early acute lesion of in a Labrador with secondary Yager, J. A. and Wilcock, B. P. Color Atlas and acral lick dermatitis in a Labrador. infection. For chronic lesions  Chronic lesions with secondary Text of Surgical Pathology of the Dog and Cat Dermatopathology and Skin Tumours, volume 1; David Grant, MBE, BVetMed, CertSAD, FRCVS, graduated from the deep pyoderma require long-term pp57-58. Wolfe, 1994. RVC in 1968 and received his FRCVS by examination in 1978. He was antimicrobial systemic therapy based  Figures 1 and 2 courtesy of Professor hospital director at RSPCA Harmsworth for 25 years until his retirement on sterile deep biopsy sampling. David Lloyd and Professor Ross Bond and from the RSPCA and is currently engaged in writing and lecturing Treatment will be required for six to colleagues from the dermatology group of internationally, mainly in veterinary dermatology. eight weeks and as long as four to the Royal Veterinary College, London.