Evaluation of sedative and cardiorespiratory effects of romifidine and romifidine-butorphanol in cats

OBJECTIVE: To determine sedative and cardiorespiratory effects of romifidine alone and romifidine in combination with butorphanol and effects of preemptive atropine administration in cats sedated with romifidine-butorphanol. DESIGN: Randomized crossover study. ANIMALS: 6 healthy adult cats. PROCEDURES: Cats were given saline (0.9% NaCl) solution followed by romifidine alone (100 microg/kg [45.4 microg/lb], i.m.), saline solution followed by a combination of romifidine (40 microg/kg [18.1 microg/lb], i.m.) and butorphanol (0.2 mg/kg [0.09 mg/lb], i.m.), or atropine (0.04 mg/kg [0.02 mg/lb], s.c.) followed by romifidine (40 microg/kg, i.m.) and butorphanol (0.2 mg/kg, i.m.). Treatments were administered in random order, with > or = 1 week between treatments. Physiologic variables were determined before and after drug administration. Time to recumbency, duration of recumbency, time to recover from sedation, and subjective evaluation of sedation, muscle relaxation, and analgesia were assessed. RESULTS: Bradycardia developed in all cats that received saline solution and romifidine-butorphanol or romifidine alone. Preemptive administration of atropine prevented bradycardia for 50 minutes in cats given romifidine-butorphanol. Oxyhemoglobin saturation was significantly decreased 10 minutes after romifidine-butorphanol administration in atropine-treated cats. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that administration of romifidine alone or romifidine-butorphanol causes a significant decrease in heart rate and that preemptive administration of atropine in cats sedated with romifidine-butorphanol effectively prevents bradycardia for 50 minutes.