Sedative effects of three doses of romifidine in comparison with medetomidine in cats.

Objective: To compare the sedative effects of three doses of romifidine with one dose of medetomidine.

Study Design: Prospective blinded experimental cross-over.

Animals: Five adult Domestic Short Hair cats.

Methods: Cats were administered romifidine at 80, 120 and 160 μg kg(-1) or medetomidine at 20 μg kg(-1) (M20) intramuscularly (IM). Sedative effects were assessed for 3 hours by summing the scores given to posture, auditory response, resistance to positioning, muscular relaxation, and response to noxious stimuli, giving a total sedation score (TS). The area under the curve (AUC) of TS ≥7 (the score considered as clinically useful sedation) was calculated. Times to stages of sedation were determined. Some physiological parameters were measured. Data to compare treatments were analysed by anova or Kruskal-Wallis test as relevant.

Results: All treatments gave a TS considered clinically useful. There were no significant differences between treatments for times to onset of sedation, maximum TS reached, or AUC. Differences between romifidine treatments for other sedation parameters were not significant but the time to maximum TS and to recovery was shortest in M20. Heart rate (HR) fell significantly with all treatments and, although with M20 it recovered at 65 minutes, it remained significantly depressed for 3 hours after all romifidine treatments. Most cats vomited, and/or hypersalivated after all treatments.

Conclusions: Doses of 80, 120 and 160 μg kg(-1) romifidine IM produce sedation in cats which is similar to that following medetomidine 20 μg kg(-1) . Recovery from sedation and of physiological parameters was quickest after M20.

Clinical Relevance: Doses of romifidine considerably lower than those investigated by previous authors give a clinically useful level of sedation, and their use might result in less side effects and a quicker recovery.