PHYSIOLOGICAL AND ANESTHETIC EFFECTS OF HAND INJECTION VERSUS DARTING TO INDUCE ANESTHESIA IN CHIMPANZEES (PAN TROGLODYTES).

Great ape anesthesia is reported to carry a significant risk. Therefore, techniques aiming to reduce stress and increase welfare, such as hand injection of anesthesia induction agents, have received considerable attention in zoo, laboratory, and captive wildlife environments. However, there is little evidence to support the superiority of such techniques. To investigate this issue, anesthesia records of healthy zoo-housed chimpanzees (Pan troglodytes) between 2012 and 2017 in which the animal was either darted or hand injected were analyzed (n = 50). Sex, age, induction, muscle relaxation, and overall anesthesia quality as well as recovery ratings, heart rate, systolic, mean and diastolic blood pressure, respiratory rate, end-tidal CO2, oxygen saturation (SpO2), and body temperature were analyzed. Chimpanzees that were darted showed statistically significantly higher heart rate, SpO2, and body temperature than those that were hand injected. It was found that darted chimpanzees were also significantly more likely to have poorer perianesthetic muscle relaxation and overall anesthesia rating scores. This study provides further evidence that the use of hand injection can reduce factors associated with stress and improve the quality of chimpanzee anesthesia.