Statement of the Problem

A dog was evaluated because of a chronic history of acral lick dermatitis.

Signalment

The patient was a 9-year-old 15.9-kg (35.0-lb) spayed female mixed-breed dog.

History

The dog had been obtained from a shelter at 1 year of age. The dog was a family pet and was the only dog in the household. The owner had attempted to crate train the dog a short time after it was adopted; however, confinement induced signs of anxiety in the dog. Ever since that time, the dog had been allowed free access to the living areas of the home. The dog commonly followed the owner around the home and was rarely left in the home alone because the owner was retired. The dog urinated on the carpet (typically twice monthly) when the owner was not at home. The owner walked the dog off the property 3 times each day because the home did not have a fenced yard. A flat buckle collar and leash were used for the walks.

The owner described the dog's personality as anxious and said it had a high amount of energy. The dog licked its forelimbs and commonly looked out windows and barked at passersby. While barking, the dog's hackles were raised. In the home, the dog avoided approaching strangers but was not aggressive. The owner considered the barking to be behaviorally normal for the dog, but thought the amount of barking was excessive. The dog did not stop barking when it was reprimanded or cued to perform an alternate behavior. Although the dog had attended obedience classes, the only cue it responded to was a verbal command to sit.

The dog had been licking and chewing the dorsal aspect of its left carpal and metacarpal region for 7 years. The behavior could occur multiple times in an hour, and each episode lasted 15 minutes or longer. The dog had a lesion that was visually consistent with acral lick dermatitis. The behavior occurred in the owner's presence, and the owner did not know whether the behavior occurred when the dog was left alone. The owner disciplined the dog when it was caught licking its forelimb. The owner disciplined the dog by snapping her fingers, verbally scolding the dog, or giving a correction by use of the dog's collar. The dog briefly stopped the behavior when it was disciplined.

The owner had taken the dog to several veterinarians during previous years for evaluation and treatment of the lesion. The lesion was evaluated as a medical problem; it had not been evaluated as a behavioral problem. Previous medical treatments had resulted in partial resolution or visual improvement of the lesion. At the time of the behavioral evaluation, the dog was wearing an Elizabethan collar, and its left forelimb was bandaged. Recent medications prescribed for the dog included an antihistamine (hydroxyzine hydrochloride; 1.6 mg/kg [0.7 mg/lb], PO, q 12 h), an antimicrobial (cephalexin; 31.4 mg/kg [14.3 mg/lb], PO, q 12 h), and an analgesic (tramadol hydrochloride). The antihistamine and antimicrobial had been administered to the dog for 4 weeks at the time of the behavioral evaluation. Tramadol had not been administered to the dog.

The owner described the behavior problem as waxing and waning in intensity. Triggers at the onset of the behavior were not identified. However, the behavior had started at the time the dog moved into the current home, which lacked access to a fenced yard.

Physical Examination Findings and Laboratory Results

The dog's body condition was considered clinically normal. Results of a neurologic examination were unremarkable. The most important physical examination finding was a 2 × 7-cm granuloma on the dorsal aspect of the left carpal and metacarpal region. The lesion was raised and erythemic, and the surrounding hair coat was stained from saliva. Results of radiographic examination of the left forelimb suggested soft tissue inflammation. Findings on cytologic examination of skin scrapings were unremarkable. Results of a heartworm antigen test for detection of occult infection and results of serologic analyses for detection of tick-transmitted diseases were negative. Results of a CBC and serum total thyroxine concentration assay were within the respective reference ranges. Results of serum biochemical analysis were unremarkable except for an incidental finding of moderate hypophosphatemia and a total bilirubin concentration that was slightly higher than the upper limit of the reference range secondary to hemolysis of the blood sample.¹ Results of a urinalysis were unremarkable except for alkaluria, proteinuria, and detection of few triple phosphate crystals. Alkaluria causes a false-positive result for proteinuria.^2,3 Monitoring of the laboratory analysis variables with results outside reference ranges and feeding of a novel protein and carbohydrate diet intended for senior dogs were recommended.

Diagnosis

Medical conditions associated with acral lick dermatitis include organopathies, endocrinopathies, neoplasia, cutaneous trauma or foreign body, neurodermatitis, dermatologic conditions (including allergy), ectoparasitism, bacterial or mycotic infections, exposure to environmental irritants, and any condition related to pain.^4–6 Medical diseases or malaise can contribute to stress and anxiety. Physical examination findings and diagnostic test results for the dog of the present report were not suggestive of a direct medical cause of the acral lick dermatitis. In addition, previous medical treatment with antihistamines and prednisone (0.49 mg/kg [0.22 mg/lb], PO, q 12 h) did not result in resolution of the problem. Differential diagnoses for a compulsive behavioral disorder included an attention-seeking or conditioned unwanted behavior, acute conflict behavior or displacement behavior, hyperactivity, generalized anxiety, and separation anxiety.^4,5,7

A diagnosis of compulsive disorder was made on the basis of the detailed behavioral and medical history. Compulsive disorders have been described as an expression of stress, frustration, or conflict.⁸ Prolonged repeated frustration and conflict may cause a conflict behavior to develop into a compulsive disorder. Behavior of the dog of this report was out of context, exaggerated, ritualistic, and sustained. The diagnosis was confirmed by the subsequent response to treatment. The prognosis was fair for improvement in the dog's behavior.

In addition, a diagnosis of territorial barking was made. Excessive barking at pedestrians walking past the home was considered a source of conflict and anxiety. Body language and piloerection indicated fear and uncertainty when unfamiliar people approached the property. The dog did not show aggression toward strangers who entered the home or when meeting unfamiliar people when it was off the property.

Video recording of the dog when it was home alone was advised to ascertain whether the compulsive behavior occurred when the owner was absent and, if so, to allow comparison of the frequency, intensity, and duration of the licking behavior in the presence and absence of the owner. Evaluation of the recording allowed identification of separation anxiety as a stress factor leading to conflict. Separation anxiety was considered a probable diagnosis because of attachment behaviors.⁹ In addition, urination in the home, although infrequent, occurred only when the owner was absent. The dog's early history indicated distress when it was confined to a crate and alone.

Disciplining of the dog likely contributed to anxiety or inadvertently reinforced the behavior.^5,6,10 Attention was not thought to be solely responsible for conditioning the excessive licking behavior, especially if excessive licking of the forelimb occurred in the owner's absence.

Treatment

The owner was advised to keep a daily diary of the dog's behavior in which behavioral changes were subjectively graded on a scale of 1 (low frequency, duration, and intensity) to 10 (high frequency, duration, and intensity). Continued video recording of the dog when the owner was absent and monitoring for signs of separation anxiety or distress were also advised.

The owner was advised to avoid rewarding the dog's compulsive behavior with any form of casual attention when it followed the owner around the home. Interactions between the owner and dog were to be structured in the format of a cue, response, and reward.⁶ The owner was advised that the dog should sit prior to receiving any form of attention. Consistent and predictable interactions reduce anxiety and avoid inadvertent reinforcement of undesirable behaviors.⁵

Verbal or physical discipline of the dog was to be avoided in all situations. Instead, the owner was advised to perform response substitution. For response substitution to be effective, clicker training was used to teach the dog cues to come, sit, and lie down. Response substitution was conducted by interrupting the undesired behavior, calling the dog's name, giving cues to come and sit, and rewarding the appropriate responses with a food treat. Food-dispensing toys were used for the reinforcement of desirable behavior and were offered to the dog prior to the expected onset of compulsive behavior. The dog did not lick food-dispensing toys and a forelimb at the same time.

The owner was instructed to prevent the dog from looking through the front door and window of the home. Use of temporary window film was suggested. The owner was advised that the dog should wear a light leash attached to a flat buckle collar when in the home and supervised. The leash was used to help facilitate response substitution for territorial barking.

A structured daily routine was advised, including provision of meals twice each day,^a clicker training the dog to respond to a down-stay command as a means of fostering independence from the owner, and leash-walking the dog off the property. Fencing the property was also suggested. Mental stimulation for the dog (consisting of exercise and positive reinforcement training) was advised to reduce anxiety.

Clomipramine hydrochloride^b (2.5 mg/kg [1.1 mg/lb], PO, q 12 h), which is FDA approved for treatment of separation anxiety in dogs, was prescribed to reduce fear and anxiety and facilitate learning of appropriate alternate behaviors instead of undesirable ones.¹¹ Clomipramine, a tricyclic antidepressant, was chosen because it has serotonergic effects and is beneficial for the treatment of compulsive disorders in dogs.^12,13 The owner was advised that this was extralabel use of the drug and that onset of action may be delayed (possibly 4 to 6 weeks) for animals with compulsive disorders. Use of the Elizabethan collar was continued to allow the left forelimb lesion to heal. Antimicrobial administration was continued for 3 weeks after healing of the lesion. Use of the bandage was discontinued, and an antibacterial and antifungal shampoo (4% chlorhexidine gluconate) was applied topically (2 to 3 times/wk for a 10-minute duration of contact time) until the lesion healed. Tramadol was not administered, and administration of hydroxyzine was discontinued because simultaneous use with tricyclic antidepressants is contraindicated.^14–16

Follow-up

Evaluation of a video recording of the dog indicated an increase in the frequency of compulsive behavior when it was left alone. In addition to the prior recommendations, the owner was advised to be nonchalant during departures and when arriving home to minimize anxiety associated with these situations. The dog was ignored for 20 minutes prior to the owner's departure from the home, and a food-dispensing toy was offered to the dog 10 minutes prior to the owner's departure.¹⁷ The purpose was to prevent association of the food-dispensing toy with impending owner departure and to preoccupy the dog while the owner was preparing to depart from the home.

During the 2 months following the behavioral consultation, the Elizabethan collar was removed for increasingly longer periods. The frequency of the compulsive behavior had decreased, and the forelimb lesion had improved. The frequency of territorial barking behavior had decreased, and inappropriate elimination in the house had ceased.

Three months after the behavioral evaluation, the left forelimb lesion had completely healed. The dog was no longer wearing the Elizabethan collar. Six months after the evaluation, the lesion had not recurred. Administration of clomipramine was continued at the prescribed dosage; reduction of the dosage and discontinuation were to be considered in the future. The owner was pleased with the improvement in the dog's behavior.