The effects of two intramuscular sedation protocols on echocardiographic variables in cats following sedation and blood donation.

OBJECTIVE To compare effects of 2 IM sedation protocols, alfaxalone-butorphanol (AB) versus dexmedetomidine-butorphanol (DB), on echocardiographic (ECHO) variables in cats following sedation and blood donation. DESIGN Experimental randomized, blinded crossover study. SETTING University teaching hospital. ANIMALS Eleven client-owned healthy cats. INTERVENTIONS Cats received a baseline ECHO without sedation prior to their first donation. Cats were sedated intramuscularly with AB (alfaxalone, 2 mg/kg, and butorphanol, 0.2 mg/kg) for 1 donation and DB (dexmedetomidine, 10 μg/kg, and butorphanol 0.2, mg/kg) for another, with a minimum 6 weeks between donations. A post-sedation, post-donation ECHO was performed after each blood donation. MEASUREMENTS AND MAIN RESULTS Eight cats completed the study. Compared to baseline, DB combined with blood donation decreased heart rate (-84/min; P < 0.0001), fractional shortening (-16.5%; P < 0.0001), ejection fraction (-21.0%; P = 0.0002), and cardiac output (-292 mL/min, P = 0.0001); AB combined with blood donation increased heart rate (+45/min; P = 0.0003) and decreased left ventricular end diastolic volume (-1.57 mL; P < 0.0001). Compared to AB, DB decreased heart rate (-129/min; P < 0.0001) and fractional shortening (-21.6%; P < 0.0001) and increased left ventricular end-systolic (+1.14 mL; P = 0.0004) and diastolic volumes (+1.93 mL; P < 0.0002). Cats administered DB had a significant increase in regurgitant flow across mitral, aortic, and pulmonic valves following blood donation (P < 0.05). One cat administered DB developed spontaneous echo contrast in the left ventricle following donation. CONCLUSIONS AND CLINICAL RELEVANCE Compared to AB, DB had more pronounced effects on ECHO variables in cats following IM sedation and blood donation. Due to its minimal impact on ECHO variables, AB may be a more desirable sedation protocol in this population of cats.