Statement of the Problem

A dog was examined because of an inability to remain calm despite adequate exercise and extensive training and because of fear of sudden, loud, short noises.

Signalment

The dog was a 2-year-old neutered male German Shorthaired Pointer that weighed 28.1 kg (61.8 lb).

History

The owners had acquired the dog from a breeder at 9 weeks of age. Controlling the dog's play biting, jumping, and barking was extremely difficult even at this age, despite skill and experience of the owners in training dogs. The dog was unable to relax and was easily distracted, and the owners had made no progress in teaching it to be calm. When not crated, it paced constantly, picking up or knocking over objects in reach, and frequently sought attention. The owners consistently ignored these behaviors; however, the behaviors failed to extinguish. Over a 5-hour period, the dog would take only short rests totaling approximately 30 minutes. The dog panted continuously and was highly reactive to noise and movement, barking frequently. If given a bone, the dog would chew it for a few minutes, get up and pace, return to chewing, and repeat this behavior for about an hour. The dog settled in the crate when the owners left the house; however, if crated or restrained in the presence of the owners, it became anxious, whining and pacing continuously. The only other times it would settle were when it was totally exhausted after exercise or the weather was extremely hot. The owners had attempted various strategies, unsuccessfully, to control its behavior. These included response substitution (teaching and rewarding incompatible alternative behaviors), ignoring attention-seeking behavior, structuring social interactions by giving a command before all interactions and rewarding its compliance (command-response-reward protocol), teaching and reinforcing calm behaviors, general training, and increasing daily exercise. The dog had attended clicker, obedience, rally, and agility training classes and currently received search-and-rescue training for 6 h/wk. Despite this extensive training, the dog often failed to respond to commands and to learn new or alternative behaviors. In addition to training, the dog was walked off the property 3 to 4 times a week. Since the dog had been a puppy, it had been fearful of short, loud noises. For example, after one of the owners kicked its food bowl, the dog would not come back into the room to eat for days. After one of the owners dropped a child safety gate near a doorway, the dog remained cautious around the doorway months later. When the sound of fireworks displays could be heard, the dog constantly whined and would not go outside the following week, even to eliminate.

Physical Examination and Laboratory Findings

At the behavior consultation, the dog entered the room excited and hyperactive and remained this way for the 2-hour consultation. It was friendly, confident, and outgoing and displayed no overt signs of anxiety. It was in constant motion, pacing around the room; jumping on tables, chairs, and people; nosing people and items; and scratching at the door. These behaviors were ignored. The dog grabbed objects it could reach with its mouth, including the doorknob, a clipboard, the light switch, and eventually a towel before all loose items were removed from the room. When the dog was given toys, these engaged the dog's attention for only a few minutes before it began pacing again.

The dog had tachypnea (50 breaths/min; reference range, 10 to 30 breaths/min), high-normal heart rate (170 beats/min; reference range, 60 to 180 beats/min), excessive salivation, and a slightly high rectal temperature (39.7°C [103.5°F]; reference range, 37.5° to 39.2°C [99.5° to 102.5°F]).¹ Results of a neurologic examination, routine serum biochemical analyses, and a CBC were unremarkable. Thyroxine and thyroid-stimulating hormone concentrations were within the reference ranges, making thyroid dysfunction unlikely.

Diagnosis

Hyperactivity may be seen in genetically predisposed breeds, occur secondary to inadvertent reinforcement, or result from physiologic abnormalities.^2,3 Although German Shorthaired Pointers are working dogs predisposed to high levels of energy and activity, the unremitting nature of overactivity and arousal across various contexts, failure to respond to behavior modification, short attention span, poor trainability relatively high heart rate for a large-breed dog, tachypnea, high rectal temperature, and excessive salivation supported a diagnosis of physiologically based hyperactivity^2–5 The persistence of these signs despite adequate exercise, attempts to reinforce calm behavior, and ignoring attention-seeking and excitable behavior further supported this diagnosis. Medical conditions such as metabolic disturbances associated with hepatic abnormalities, aberrant glucose metabolism, thyroid gland dysfunction, and neurologic conditions may result in hyperactivity⁶ However, results of routine serum biochemical analyses were within reference limits, the dog's thyroid gland function was normal, and no neurologic abnormalities were detected, making these conditions less probable, although they remained as differential diagnoses. The dog also had attention-seeking behavior, characterized by jumping on and pawing at people. This, combined with its ability to settle in its crate in the owners' absence, suggested that there were conditioned components to its behavior. However, an ability to settle in specific situations has been noted in dogs with hyperkinesis.⁴ Hyperactivity, hypervigilance, excitability, panting, and pacing may also be signs of anxiety.⁷ Although anxiety may have exacerbated the dog's hyperactivity, it did not explain its generally confident and engaging body language. Noise phobia was diagnosed on the basis of the dog's maladaptive fear response to noises.⁸

Treatment

Central nervous system stimulants,³ fluoxetine,⁹ and clomipramine⁴ have been used in the treatment of hyperactivity disorders in dogs. A diagnosis of hyperkinesis is confirmed by a calming response to administration of CNS stimulants (commonly dextroamphetamine or methylphenidate).^2,10 As a diagnostic trial, the dog was treated with methylphenidate. The owners were instructed to start with an initial dosage of 20 mg (0.7 mg/kg [0.32 mg/lb]), PO, every 12 hours, and to increase the dosage by 10 mg (0.4 mg/kg [0.18 mg/lb]) every third day until either a decrease or increase in hyperactivity was noted or a maximum dosage of 60 mg (2.1 mg/kg [0.95 mg/lb]), PO, every 12 hours was reached.³ The owners were also advised to discontinue administration of methylphenidate if the dog developed inappetence, sleeplessness, or aggression. Trial administration of dextroamphetamine was considered more difficult because the dog required sedation to be handled at the veterinary clinic and the standard dextroamphetamine trial involves recording heart rate, respiratory rate, and activity levels before and every 30 minutes after administration of the drug, with decreases in these measures expected in dogs with hyperkinesis. Treatment of hyperactivity also involves behavior modification.⁴ However, because all previous attempts had been unsuccessful, the owners were not instructed to attempt additional behavior modification until a reduction in hyperactivity was seen. The owners were instructed to walk the dog off the property for as long as possible twice daily and to encourage other interactive exercises to provide an appropriate outlet for activity. To treat the dog's noise phobias, systematic desensitization was combined with counterconditioning¹¹ (classically conditioning a positive emotional response to noises). One owner would drop an item quietly at a distance, and the other would put food in the dog's mouth. Gradually, the intensity of the sound was increased and the distance decreased. The exercise was repeated with different sounding items until generalization occurred. At other times, whenever there was a loud noise (eg, thunder), the owners were instructed to give the dog a food treat. If it would not take a treat, the owners were instructed to smear peanut butter or cheese spread in its mouth. A decrease in general reactivity was anticipated once the dog's hyperactivity was successfully managed, and no additional medication was prescribed for noise phobia at this time.

Follow-up

No decrease or increase in hyperactivity was noted during trial administration of methylphenidate (up to 60 mg, PO, q 12 h); however, the dog became markedly more distracted during training sessions. Therefore, a diagnosis of hyperkinesis was considered unlikely, and treatment with fluoxetine at a dosage of 30 mg (1.1 mg/kg [0.5 mg/lb]), PO, every 24 hours on a trial basis was recommended. Three weeks later, the dog was pacing less, was more responsive to commands, and would chew on bones for 20 minutes at a time. The dog was less reactive to noises and movement and responded to response substitution. At the veterinary clinic, the dog was more relaxed and accepted handling. For the first time, it received a best-performer award at a training session, despite the sounds of horns and revving engines from an auto show taking place at an adjacent location. When put into its crate, the dog whined initially but lay down and settled within a few minutes, even when an owner was present. The owners were instructed to commence behavior modification. They were advised to use clicker training to mark and reward calm behavior at any time and to teach the dog to stay in a relaxed down position, gradually increasing duration. To prevent pacing in the house, the owners were instructed to send the dog to its mat and reward it for remaining calm by tossing treats or securing a food-dispensing toy³ near its mat. They were advised to ignore all attention-seeking behavior and to initiate interaction only when the dog was calm. The command-response-reward protocol was recommended to establish a structured and appropriate form of interaction. One month later, the dog continued to have a marked reduction in hyperactive behavior; however, it remained fearful of noises. Clonazepam (2 mg, PO, q 12 h) was prescribed, and 1 week later, the owners reported that the dog was less reactive to noises, recovered more quickly after hearing a noise, and was making progress with the systematic desensitization and counterconditioning exercises. Two months after administration of fluoxetine was begun, the dog developed nausea, vomiting, diarrhea, and recurrent episodes of marked abdominal distention. Because the reported adverse effects of fluoxetine include gastrointestinal abnormalities,¹² the owners were advised to discontinue fluoxetine administration and to consult with their veterinarian. Owing to the potentially serious consequences of possible gastric dilation, it was decided to immediately discontinue treatment with fluoxetine, rather than use a standard weaning protocol. It was suggested that an increased dosage of clonazepam might have been required once the dose of fluoxetine was reduced, because fluoxetine inhibits the metabolism of clonazepam.¹² A diagnosis of inflammatory bowel disease of suspected allergic origin was made by a veterinary medicine internist. The dog was treated with a low-allergen diet^b and famotidine, and all gastrointestinal signs abated. However, the dog's hyperactive behaviors returned. The owners requested that medication with fluoxetine be reinstituted, and after consultation with the referring veterinarian, fluoxetine (30 mg, PO, q 24 h) was prescribed. The dog also received clonazepam (3 mg, PO, q 12 h). Six months after the initial consultation, the dog was relaxed, responsive, focused, and easier to train in all contexts, and it no longer constantly barked, paced, or sought attention. During the sound of fireworks, the dog would eliminate outside and only lifted its head when one exploded. Counterconditioning to noises was going well, and when one of the owners dropped a metal tool box onto a hardwood floor, the dog approached for a treat. Although medication has been successfully withdrawn in some dogs with hyperactivity,^4,5,13,14 the owners were reluctant to taper medication owing to the resumption of hyperactivity when medication with fluoxetine was previously stopped. Clonazepam was being used only during storms.