Statement of the Problem
A cat was evaluated because of pouncing, scratching, and biting the owners' ankles; biting the owners when petted; hissing at and biting visitors; and swatting at veterinary staff.
Signalment
The patient was a 4-year-old 7.1-kg (15.6-lb) castrated male domestic shorthair cat.
History
The patient was adopted when it was 6 weeks old and housed indoors. When the cat was 4 months old, it started to pounce on the owners' ankles. Initially, the owners responded by playing with the cat. However, the behavior worsened so that the cat stalked its owners every morning in a crouched body posture with its ears forward and the tip of its tail twitching. The cat would then pounce on the owners' ankles, hold on with its front paws, scratch with its hind paws, and bite. Scratching typically caused bleeding of the owners, but biting did not. The cat would let go after a few seconds and slowly bound away with its tail up. Yelling at the cat or using a water pistol had not been successful in reducing the severity or frequency of the behavior.
The cat frequently rubbed on its owners, who responded by petting it. After a few seconds of petting its back, the cat hissed and then bit (occasionally breaking through the owners' skin) with the tip of its tail twitching, ears positioned flat and to the sides, and pupils dilated. When petted on the ventral aspect of its abdomen, the cat grabbed the owners' arms, bit, and scratched with its hind paws. After biting, the cat ran away.
The cat hissed at strangers with its ears positioned flat and to the sides and pupils dilated while being held by the owners. This behavior had started when the cat was 3 months old. If strangers approached the cat when it was not restrained, it hissed and ran away. As the patient grew older, it sometimes lunged and bit at strangers, occasionally breaking skin, before fleeing. If the cat was ignored, it did not approach, hiss, or lunge at visitors.
When the patient was 6 months old, it scratched veterinary staff for the first time. This behavior problem gradually worsened. Four weeks before the time of the behavioral consultation, the cat's aggression prevented its primary care veterinarian from performing a physical examination. Therefore, the cat was sedated for the physical examination; results were unremarkable, including findings for the cat's skin. At home, the patient did not have aggression when the owners restrained it (eg, for administration of pills). The cat did not have a history of medical or elimination problems and was fed a well-balanced diet.
Physical Examination Findings and Laboratory Results
During the behavioral examination, the cat explored the consultation room with a low body posture and tail position. The patient was slightly overweight (body condition score, 6/9). No other abnormalities were observed. When the cat was approached by the veterinarian, it arched its back, hissed, flattened its ears, and then ran into the carrier. In the carrier, it growled, hissed, and swatted. Performance of a CBC, serum biochemical analysis, urinalysis, FIV and FeLV tests, and analysis of circulating thyroid concentrations were recommended to detect potential medical causes of the patient's aggression1–3 and to assess metabolic function before administration of psychoactive medication4; however, the owners declined such testing. Because the cat required sedation for performance of a physical examination and had recently been examined by its primary care veterinarian, further examination of the patient was not attempted.
Diagnosis
The following 4 behavior problems of the patient had been identified: scratching and biting of the owners' ankles, scratching and biting of the owners when petted, hissing and biting of visitors, and swatting at veterinarians. For scratching and biting of the owners' ankles, play-related aggression was diagnosed because of the cat's body language, absence of vocalization, age at onset, directed behavior toward moving stimuli (eg, ankles), and occurrence of the behavior during specific situations.1,2,5–9 A lack of exposure to negative or positive punishment during rough social play (because of early separation from littermates), the initial owner reinforcement of the behavior, and the fact that the patient was the only cat in the household likely favored the behavior.1,2,5–12 Although cats rarely have true predatory behavior toward humans,13 elements of predation are part of play.5,9 Cats should have inhibition of biting during play,6,10 but not during predation.2 Biting during play can cause injury to skin of humans.7,14 True predation was ruled out for the cat of the present report because it had other play-related behaviors.2,6,10 Play and predation were ruled out as causes of the other behavior problems of the patient because of its body language.1,2,5,13
For the cat's scratching and biting of the owners when it was petted, a diagnosis of petting intolerance was made.2,5–8 Petting-induced aggression may be caused by overstimulation of neurologic pathways common to touch and pain sensations.15 The context in which the behavior occurred and the cat's body language, sex, and social demeanor were consistent with this diagnosis.2,5–8 The patient's body language indicated it had defensive aggression.2,5 One author1 indicated biting during petting preceded by tail flicking, flattening of ears, and growling are status-related aggression. Although status-related aggression is not a clearly defined or widely accepted diagnosis for cats,7,16 most authors agree that the purpose of that type of aggression is to control a situation and that it is not characterized by defensive signaling.2,7,8,17 Therefore, status-related aggression was ruled out as a cause of the behavior problems of the cat.
Fear-related aggression was ruled out as a cause of the cat's pouncing on its owners because it did not have defensive body postures.1,2 However, the cat's body postures and vocalization to veterinary staff and visitors indicated it had fear-related aggression.3,18 Fear-related aggression toward veterinary staff was likely attributable to an association of such people with unpleasant experiences or stress caused by an unfamiliar environment.2,18–20 The early onset of such behavior and the absence of a history of aversive experiences with visitors or a lack of human contact during the socialization period of the cat indicated it had a genetic predisposition to the problem.1,2 Instrumental conditioning with negative reinforcement (humans backing away from the cat) likely caused the cat to continue its aggressive responses.2 Redirected aggression was ruled out for all 4 behavior problems identified in the patient because the primary stimulus for aggression was always accessible to the cat and no additional inaccessible stimuli were identified.2,5 Sexual aggression was ruled out for the patient because it did not have mounting behavior or pelvic thrusting.5,7,8 For the visitor-related behavior problems, territorial aggression was ruled out because of the early onset of the behaviors and the cat's avoidance of visitors when possible.2,3,5,21
Aggression attributable to partial seizures was ruled out because there were clearly identifiable triggers, the cat remained conscious, and no pre- or postictal periods were identified.5,22,23 Although testing for determination of circulating thyroid concentrations was declined by the owners, the absence of clinical signs and early onset of aggression did not indicate the patient had an endocrine disorder.5,24,25 Medical problems (such as skin problems), which could have triggered pain-related aggression or reduced the threshold for irritable or petting-related aggression,9,15 were not identified for the cat. Laboratory analyses and a physical examination while the patient was not sedated were not performed; however, no information in the cat's history indicated it had urological, infectious, or orthopedic problems or neuropathic pain. Hyperesthesia syndrome was ruled out because the cat did not have skin rippling.15
Treatment
To stimulate appropriate play behavior, daily play sessions with toys that move unpredictably or dispense food were recommended for the cat.2,6 Especially during mornings, a feeder toya was to be provided for the patient (for differential reinforcement26 of playing with a toy instead of stalking the owners).7 If the cat stalked the owners, the behavior was to be interrupted.1,2 Gentle hand clapping was recommended to interrupt behaviors because physical punishment often causes fear-related aggression in cats.2,6 If the cat interrupted the stalking sequence, the owners were instructed to throw a toyb that was big enough to allow the cat to kick the toy with its hind paws to redirect its play behavior.6,14 We asked the owners to contact us if hand clapping increased arousal of the cat.
The cat was to be petted only on its head and neck,7 which are areas that one cat grooms with its tongue on another cat, usually a preferred associate animal, during grooming bouts.27,28 Petting of the cat was to be discontinued immediately and without punishment in response to body language cues preceding biting behavior.7,8,15 Petting sessions were to be of a short duration and end before the patient had signs of agitation.7
The recommendation was made that visitors ignore the cat. A desensitization and counterconditioning protocol was suggested; in the presence of visitors, the owners were to play with the cat while gradually decreasing the distance between it and the visitors over several sessions. The recommendation was made to allow the cat access to elevated areas in the living room of the home for retreat and observation.3,29,30 One bedroom was to have litter boxes, elevated areas, and toys so that it would be a safe room and allow separation of the patient from guests if necessary. Use of a synthetic pheromone diffuserc was recommended because it can be helpful in reducing anxiety,2,31 although the efficacy of that product varies among cats.32 A desensitization and counterconditioning program was recommended to decrease the intensity of the cat's response to stimuli associated with visits to veterinary clinics, such as carriers, restraint and handling, disinfectant odors, and, eventually, the primary care veterinarian's clinic.18
Fluoxetine (0.7 mg/kg [0.3 mg/lb], PO, q 24 h), a selective serotonin reuptake inhibitor, was prescribed for the cat. Although the drug is not approved for the treatment of aggression in cats, fluoxetine has been effective for the treatment of a cat with human-directed aggression19 and for the treatment of other behavior problems in cats.33–36
Buspirone, a serotonin 1A receptor partial agonist, increases friendly social behavior37 and may be helpful for treatment of petting intolerance in cats,7,8 but that drug also has less potent anxiolytic effects than selective serotonin reuptake inhibitors38; therefore, buspirone was not prescribed for the cat. Fluoxetine was chosen for treatment of the cat instead of GABAergic α-casozepine39 or benzodiazepines40,41 and l-theanine (an amino acid with effects potentially mediated via glutamate receptorsd) because of the association between aggression and function of serotonergic pathways.1,42
Follow-up
One week after the behavioral examination, no adverse effects of fluoxetine (eg, anxiety, decreased appetite, or sedation36,38) were observed, and no episode of aggressive behaviors had occurred. Although the anxiolytic and aggression-modifying effects of selective serotonin reuptake inhibitors are attributable to serotonin receptor downregulation38,43 (which can take up to 6 weeks to develop36,43), such effects have been detected after a few days of administration.36 For the cat of the present report, tail twitching was a reliable predictor for biting during petting, and stopping petting at that time prevented aggression. The owners of the cat were satisfied with the outcome of treatment at that time, and a desensitization and counterconditioning program for association of petting with treats7 was not instituted. The frequency of the patient's stalking behavior toward the owners was substantially reduced because of increased appropriate play, and stalking behavior could be easily interrupted and redirected. Three months after the behavioral consultation, the cat had not scratched or bitten any people, but it had hissed at visitors when they attempted to pet it (despite our recommendations). Desensitization and counterconditioning were recommended again, but the owners were content with placing the cat in the safe room when necessary. Desensitization and counterconditioning for treatment of fear behavior at the veterinary clinic had not been attempted. Six months after the behavioral consultation, the cat had not had any more aggression toward its owners or visitors. A recommendation was made to decrease the fluoxetine dosage (0.35 mg/kg [0.16 mg/lb], PO, q 24 h for 4 weeks, then 0.35 mg/kg, PO, q 48 h for 4 weeks, then discontinue). A more gradual reduction of the dosage by 25% instead of 50% every 4 weeks would have been preferable,36 but compounding of the drug would have been necessary; such treatment was declined by the owner. Four weeks after discontinuation of drug administration, the cat started hissing at visitors and nipping during petting. The owners declined to pursue treatment by means of behavior modification only. Administration of fluoxetine was reinstituted (0.7 mg/kg, PO, q 24 h), and the cat's aggression stopped. Performance of blood analyses every year to monitor metabolic function of the cat44 was discussed with the owners.
Funkitty, Premier, Midlothian, Va.
Kickeroo, KONG Co, Golden, Colo.
Feliway, CEVA Santé Animale, Libourne, France.
Dramard V, Kern L, Hofman J, et al. Clinical efficacy of l-theanine tablets to reduce anxiety-related emotional disorders in cats: a pilot open-label clinical trial (poster presentation). 6th Int Vet Behav Meet, Riccione, Italy, June 2007.
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