Evaluating Echocardiograms and Indirect Blood Pressures in Western Lowland Gorillas (Gorilla gorilla gorilla) in Three Phases of an Anesthetic Protocol
Until the majority of the great ape population is trained for awake procedures, most will require general anesthesia to perform echocardiograms for cardiac disease assessments. Within the veterinary community there is concern over anesthetic protocols that may exacerbate or artificially induce signs of cardiac disease. Although medetomidine is generally contraindicated in patients with cardiac abnormalities, the combination of ketamine/medetomidine is used frequently by many institutions due to its ease and reversibility. To date, there have been no published studies to compare physiologic or echocardiographic parameters using different protocols in the same individual. This study collected echocardiographic and blood pressure data on multiple male gorillas with and without cardiac disease. Initially, gorillas were given ketamine/medetomidine (historically used in all great apes at Omaha’s Henry Doorly Zoo and Aquarium without complication) after adding supplemental sevoflurane, and 15 minutes after reversing the medetomidine. Measurements were obtained under initial anesthetics and on gas alone. Based on data collected, the anesthetic regimen does affect certain cardiac parameters and indirect blood pressures. Without exception there was a decrease in ejection fraction (range 10–25%) with medetomidine that was not seen after reversal on sevoflurane. There is a potential for increase in chamber size with medetomidine as well as worsening of regurgitant lesions not noted after reversal on inhalant anesthesia. Indirect blood pressures were generally higher on ketamine/medetomidine, lower with the addition of sevoflurane, and considerably lower after medetomidine reversal. Results of awake echocardiograms in the same individuals appeared similar to those using inhalant anesthesia with reversal of medetomidine.
The authors thank the Creighton Cardiac Center for the generous donation of their time and equipment, Dan Cassidy, Dan Houser, Christine DuPre, and the rest of the great ape animal care staff for their remarkable training achievements and the veterinary interns and technicians for their participation and support in this study.