EVALUATION OF BLOOD GAS VALUES IN ANESTHETIZED SOUTHERN WHITE RHINOCEROS ( CERATOTHERIUM SIMUM) VENTILATED WITH A NOVEL DEMAND VENTILATOR IN A ZOOLOGICAL PARK SETTING.

Rhinoceros conservation efforts are essential to the survival of the species. One such effort is focused on using advanced reproductive technologies to produce viable northern white rhinoceros ( Ceratotherium simum cottoni) embryos for implantation into southern white rhinoceros ( Ceratotherium simum simum) surrogates. Anesthesia may be required to facilitate necessary procedures in these surrogate rhinoceros, but commonly reported side effects including hypercapnia and hypoxemia limit anesthetic recumbency time due to animal safety concerns. Although many interventions have been attempted, success in improving these physiologic parameters to date is mixed. The objective of this report is to describe arterial pH (pHa), blood gas (PaO and PaCO), bicarbonate, base excess, lactate, and cardiovascular (heart rate, direct arterial blood pressure) values recorded in seven intubated and ventilated female southern white rhinoceros anesthetized for reproductive examinations in a zoological park setting. Anesthetic induction was accomplished using etorphine, medetomidine, butorphanol, and midazolam. The primary hypotheses were that PaO and PaCO would improve after intubation and mechanical ventilation. Induction and recovery observations were also summarized. Physiologic and laboratory data were analyzed using a mixed linear regression model using ranks. Statistical significance was set at P < 0.05. The PaO increased significantly ( P < 0.001) following ventilation from a median value of 58 (range, 38-67) to 123 (range, 42-184) mm Hg. The PaCO significantly ( P = 0.003) decreased from 63 (range, 55-73) to 52 (range, 30-75) mm Hg, with a corresponding improvement ( P = 0.068) in pHa from 7.33 (7.25-7.34) to 7.37 (7.24-7.58) units. Intubation and ventilation improve respiratory parameters and may facilitate safe prolongation of anesthetic duration in white rhinoceros.