The effect of haloperidol and naloxone on excessive grooming behavior of cats.

In a double-blind cross-over study the effect of a single injection of naloxone (1 mg/kg s.c.) was investigated in 12 cats which suffered from excessive grooming with subsequent coat damage. Based on clinical observations and reports of the owners, naloxone had a beneficial effect on grooming which lasted between 2.5 weeks and 6 months (median 3 months). In another double-blind placebo-controlled study the effect of a single injection of haloperidol (2 mg/kg i.v.) was investigated in 20 cats with excessive grooming. Within 24 h haloperidol significantly reduced the time spent grooming. Four months after the injection no effect remained in nine of 10 cats injected with a placebo solution, whereas six of 10 cats injected with haloperidol the improved condition of the coat was maintained. It is hypothesized that naloxone is only effective in counteracting recently developed stereotypic behaviors and that haloperidol rather reduces stereotyped behaviors over a longer period.