Statement of the Problem

A cat was evaluated because of urine spraying of at least 6 months' duration.

Signalment

The patient was an apparently healthy approximately 6.5-year-old neutered male Himalayan cat.

History

The patient had been adopted by the owner from a veterinary hospital at approximately 6 years of age; no historical information was available. After taking the cat home, the owner kept the cat in a separate room for several days and then introduced it over 2 days to the other 2 cats in the house, an 11-year-old neutered male domestic shorthair (cat 1) and a 10-year-old spayed female Maine Coon (cat 2). All 3 cats were kept exclusively indoors. Cat 1 responded aggressively and would swat at the patient whenever it was within visual range; cat 2 would growl at the patient if it came within 1 m of her. The owner's response was to pick the patient up and to separate the cats. In general, the patient would follow the owner and was modestly attention seeking.

Within a week after the patient's adoption, urine was found on the walls in the living room and master bedroom. After 7 days, when relations between the cats did not improve, the owner isolated the patient in a bedroom while she was gone and when she was sleeping. The patient was allowed out of its room for approximately 2 h/night when the owner was home from work and could supervise the interactions between the cats.

The patient was suspected to be responsible for the urine marking because urine was no longer observed in the living room or master bedroom after the patient was isolated to the bedroom. When isolated in this bedroom, the patient defecated once daily in its litter box and urinated every 2 to 3 days on the interior wall of its litter box. Small amounts of urine were found in 5 to 10 locations daily on vertical surfaces in the room.

Approximately 1.5 months after adopting the patient, the owner returned with the patient to the referring veterinarian's office with the complaint of urine house-soiling. Analysis of a urine sample obtained by means of cystocentesis revealed concentrated urine and no signs of inflammation or cellular abnormalities. The referring veterinarian prescribed amitriptyline (2 mg/kg [0.9 mg/lb], PO, q 24 h). Two weeks later, the owner returned to the referring veterinarian reporting that the patient was drinking water excessively and behaving in an “unfriendly” manner toward her and was avoiding or resisting petting and being picked up, although it had previously solicited these activities. A urinalysis did not reveal any clinically important findings. Administration of amitriptyline was discontinued, and megestrol acetate was prescribed (1 mg/kg [0.45 mg/lb], PO, q 7 d). After 2 weeks of treatment, the owner had not seen any improvement in house-soiling frequency or in the cat's affiliative behavior toward the owner. Therefore, administration of megestrol was discontinued

During this time, the owner also initiated several environmental management techniques without apparent effect. She cleaned urine marks daily with an enzymatic cleaner and covered the walls of the patient's room with plastic sheets to facilitate cleanup. The owner replaced the regular uncovered litter box with a large uncovered plastic sweater box filled to a depth of 4 inches with a fine-grain, unscented, clumping litter that was scooped twice daily. She installed pheromone plug-in diffusers^a in the patient's room, the living room, and her bedroom and replaced them once a month for 3 months.

Physical Examination Findings and Laboratory Results

At the time of the initial behavioral examination 6 months after adoption, the patient was reportedly restricted to its room except when the owner was at home to supervise. All medications had been discontinued 6 weeks earlier. The patient's relationship with cats 1 and 2 had not changed; however, it had resumed its affiliative demeanor toward the owner. In its room, urine was still found on vertical surfaces outside the litter box 5 to 10 times daily. When observed, the patient would back up to the wall and direct urine caudally while treading its back limbs. The patient was eating and drinking normally, and its feces appeared normal.

During the behavioral examination, the patient voluntarily came out of its carrier and explored the consultation room with a relaxed body posture and ear position. The patient weighed 4.5 kg (9.9 lb), with a body condition score of 5 of 9. Results of a complete physical examination were unremarkable, except for mild epiphora of the right eye and mild gingivitis. Results of palpation of the urinary bladder and kidneys were unremarkable, and physical examination and manipulation did not reveal any responses consistent with spinal or hip pain that could make access to a litter box uncomfortable. The patient tolerated attempts to protrude its penis to examine it for abnormalities and to rule out the presence of penile spines as a sign of incomplete castration.¹ However, despite attempts by 3 veterinarians to exteriorize the cat's penis, only the tip of the penis could be visualized. It appeared hyperemic and congested.

At our request, extensive clinicopathologic testing had been performed prior to the patient's referral, including a CBC, serum biochemistry panel, urinalysis, and bacterial culture of a urine sample. No results suggestive of renal disease, diabetes mellitus, hyperthyroidism, or urinary tract infection were found. At the time of the appointment, no diagnostic imaging studies of the lower urinary tract had been performed. These were discussed with the owner, who declined further testing pending results of the behavioral plan.

Diagnosis

In multicat households with house-soiling incidents, it is important to determine which cat is responsible. Various methods for verification have been described.^2,3 In this instance, the owner had witnessed the patient spraying, and the patient was the only cat with access to the room where urine marks were detected daily.

Various medical differential diagnoses were considered before proceeding with the proposed behavioral diagnosis and treatment plan. On the basis of the difficulties encountered extruding the patient's penis and the appearance of that portion of the penis that could be seen, several hypotheses were considered. One possibility was that the patient might have experienced pain while urinating in the box, which might have led to aversion because of classical conditioning.³ Another possibility was that the patient could have had a structural abnormality, such as a persistent penile frenulum, that might prevent adoption of a normal urination posture.

For all cases of urine house-soiling, it is critical to distinguish urine marking, a social communication behavior, from inappropriate urination, a urine elimination behavior. The patient had been observed to spray urine, and urine was found on vertical surfaces in the area where the patient was confined, suggesting a diagnosis of urine marking. Most cats that urine mark continue to use the litter box for both urination and defecation,^3–5 although spraying as the sole form of urination has been described.⁶ The reported number of times the patient urinated each day (5 to 10) was greater than the 2 to 5 urinations generally considered normal for cats without elimination problems³ and was more consistent with urine marking.

Urine marking is frequently reported among cats living in multicat households.⁷ The most commonly cited causes for urine marking are agonistic interactions with other cats inside or outside the home.⁷ Such interactions may increase arousal, anxiety, or conflict behavior on the part of the affected cat. The patient described in the present report was exposed to agonistic interactions with cats 1 and 2 anytime it left the safety of its room.

Treatment

On the basis of the abnormal physical examination findings, the patient was referred to a specialty hospital for evaluation of its penis. During an examination with the cat anesthetized, it appeared that its penis was mildly underdeveloped with a persistent frenulum at the dorsal edge of the penis. Once the frenulum was cut, no other structural abnormalities were found, and the patient was discharged.

For the urine marking, environmental management techniques designed to address possible litter box aversion and arousal stimulated by intercat aggression were recommended. Environmental management alone has been shown to decrease the frequency of urine spraying in cats.⁷ For litter box management, the owner was instructed to add 2 additional litter boxes, each with different litter types, to clean all boxes once or twice daily, and to record daily the number of clumps in each box as well as the number and location of eliminations outside the box in a behavioral diary. It was recommended that the owner clean any urine outside the box with an enzymatic cleaner. The owner was to continue to restrict the patient to its bedroom when she was not present. Exposure to synthetic feline facial pheromones has been shown to be effective in decreasing the frequency of urine spraying in several studies,^8–10 but had already been tried without improvement in this case. The lack of beneficial effect of pheromone treatment in this case was consistent with reports^8,9 of urine marking in households with overt intercat aggression.

Because psychotropic agents have been used with success to manage the arousal associated with urine marking,^11,12 fluoxetine (0.5 mg/kg [0.23 mg/lb], PO, once daily with food for 2 weeks, then increased to 1.1 mg/kg [0.5 mg/lb], PO, once daily) was prescribed after the patient had recovered from surgery. Clomipramine, another reasonable medication choice, was not selected, as it is in the same drug class as amitriptyline (a tricyclic antidepressant), which had been previously prescribed with resulting unacceptable adverse effects. In addition, 2 studies of the use of clomipramine in urine spraying cats have reported that at least 1 cat became less affectionate¹³ or became irritable and less tolerant of petting.⁵ In addition to fluoxetine administration, the owner was instructed to continue the environmental modifications and to monitor the patient for adverse reactions to the medication, including decreased food intake, vomiting, and lethargy.¹¹

According to both the behavioral diary and reports from the owner, the frequency of the patient's urinations on the plastic decreased within days after administration of fluoxetine was begun. The owner reported that the patient was squatting and was urinating larger volumes at a time in the litter box. After 2 weeks, the owner was not finding any evidence of urine spraying or elimination outside the litter box. The role of the surgical procedure versus other treatments could not be differentiated.

Follow-up

Six months after the initial visit, the patient was continuing to urinate exclusively in its box, although it remained separated from the other cats when the owner was not home.