naloxone and Cat-Diseases

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.

Topics: Alopecia; Animals; Cat Diseases; Cats; Double-Blind Method; Female; Grooming; Haloperidol; Male; Naloxone; Stereotyped Behavior

Intramuscular injection of xylazine induced dose-dependent vomiting in cats (ED50 = 0.277 mg/kg); administration of standard dose of xylazine (2 mg/kg, 2 times the 100% emetic dose) induced vomiting in 100% of the cats studied. The xylazine-induced vomiting was antagonized by adrenoceptor antagonists possessing alpha 2-blocking activity, which were yohimbine, tolazoline, and phentolamine. Of these antagonists, yohimbine was the most effective; the maximal antagonistic effect was seen at 1 mg of yohimbine/kg, a dose at which the other drugs had little or no effect. At the doses studied, prazosin and phenoxybenzamine, adrenoceptor antagonists with alpha 1-blocking activity, did not prevent vomiting induced by xylazine. Beta-Adrenoceptor (propranolol), dopamine receptor (domperidone and chlorpromazine), a cholinoceptor (atropine), an opiate receptor (naloxone), and a histamine-receptor (diphenhydramine) antagonists, at the doses studied, did not prevent xylazine-induced vomiting. Pretreatment with 6-hydroxydopamine failed to prevent xylazine-induced vomiting. These results indicated that xylazine-induced vomiting in cats is mediated by alpha 2-adrenoceptors and suggested that the alpha 2-adrenoceptors mediating the vomiting attributable to xylazine may not be presynaptic alpha 2-receptors located on noradrenergic nerve terminals.

Topics: Adrenergic alpha-Antagonists; Adrenergic beta-Antagonists; Animals; Atropine; Cat Diseases; Cats; Chlorpromazine; Diphenhydramine; Domperidone; Female; Hydroxydopamines; Male; Naloxone; Oxidopamine; Propranolol; Random Allocation; Receptors, Adrenergic, alpha; Thiazines; Vomiting; Xylazine