Effects of a selective serotonin reuptake inhibitor on urine spraying behavior in cats

Objective-To determine the effectiveness of a readily available selective s erotonin reuptake inhibitor (SSRI), fluoxetine hydrochloride, on reducing p roblem urine spraying in cats, Design-Randomized placebo-controlled double-blind clinical trial. Animals-17 neutered cats > I year old with objectionable urine spraying beh avior. Procedure-Owners recorded urine-spraying events for 2 weeks (baseline). Cat s that vertically marked a mean of greater than or equal to 3 times per wee k were treated for 8 weeks with fluoxetine or fish-flavored liquid placebo. If urine spraying was not reduced by 70% by weeks 4 through 5, the dosage was increased by 50% for weeks 7 and 8. After discontinuation of treatment at the end of 8 weeks, owners recorded daily urine marks for another 4 week s. Results-The mean (+/- SE) weekly rate of spraying episodes in treated cats was 8.6 (+/- 2.0) at baseline, decreased significantly by week 2 (1.7 +/- 0 .6), and continued to decrease by weeks 7 and 8 (0.4 +/- 0.2. The mean week ly spraying rate of cats receiving placebo was 7.8 (+/- 1.5) at baseline, d ecreased only slightly during week 1 (5.5 +/- 1.8), and did not decline fur ther. When treatment was discontinued after 8 weeks, the spraying rate of c ats that had received treatment varied. The main adverse reaction to the dr ug was a reduction in food intake, which was observed in 4 of 9 treated cat s, Conclusions and Clinical Relevance-Administration of fluoxetine hydrochlori de for treatment of urine spraying in cats car be expected to considerably reduce the rate of urine marking. The frequency of spraying before treatmen t is predictive of the spraying rate when the drug is discontinued.