The influence of anesthesia with and without medetomidine on cardiac structure and function in sanctuary captive chimpanzees (pan troglodytes)

Abstract

Dependent on timing of assessment, anesthetic agents and specifically medetomidinenegatively impact cardiac function in great apes. The aim of this study was todetermine the influence of tiletamine-zolazepam with and without medetomidine oncardiac structure and function in healthy chimpanzees ( Pan troglodytes ) during aperiod of relative blood pressure stability. Twenty-four chimpanzees living in an Africanwildlife sanctuary undergoing routine health assessments were stratified by age, sexand body mass and randomized to be anesthetized using either tiletamine-zolazepam(6 mg/kg; TZ; n=13; seven males and six females) or a combination of tiletamine-zolazepam (2 mg/kg) and medetomidine (0.02 mg/kg; TZM; n= 11; five males and sixfemales). During the health checks, regular heart rate and blood pressure readingswere taken and a standardized echocardiogram was performed 20-30 minutes post-induction. Data were compared between the two anesthetic groups using independentsamples T or Mann Whitney U tests. Whileheart rate (Mean ± S.D; TZ: 76 ± 10 bpm;TZM: 65 ± 14 bpm, P = 0.027), cardiac output (TZ: 3.0 ± 0.7 L/min; TZM: 2.4 ±0.7 L/min, P = 0.032) and mitral A wave velocities (TZ: 0.51 ± 0.16 cm/s; TZM:0.36 ± 0.10 cm/s, P = 0.013) were lower in the TZM group, there were no statisticallysignificant differences in cardiac structure or the remaining functional variablesbetween groups. Furthermore, there were no statistical differences in systolic (TZ114.6 ± 14.9 mmHg; TZM: 123.0 ± 28.1 mmHg; P = 0.289) or diastolic bloodpressure (TZ: 81.8 ± 22.3 mmHg, TZM: 83.8 ± 20.1 mmHg; P = 0.827) between thegroups during the echocardiogram. This study has shown that during a period ofrelative blood pressure stability there are few differences in measures of cardiacstructure and function between protocols using tiletamine-zolazepam with or withoutmedetomidine in healthy chimpanzees.