CARDIOVASCULAR EFFECTS OF ETORPHINE, AZAPERONE, AND BUTORPHANOL COMBINATIONS IN CHEMICALLY IMMOBILIZED CAPTIVE WHITE RHINOCEROS (CERATOTHERIUM SIMUM)

Abstract

Chemical capture is an essential tool in the management and conservation of white rhinoceros ( Ceratotherium simum ); however, cardiovascular responses in immobilized megaherbivores are poorly understood. Blood pressure and heart rate responses in rhinoceros immobilized with etorphine or etorphine plus azaperone, and the effects of subsequent i.v. butorphanol administration were investigated. Six white rhinoceros were used in a randomized crossover study design with four interventions: 1) etorphine i.m.; 2) etorphine plus azaperone i.m.; 3) etorphine i.m. and butorphanol i.v.; and 4) etorphine plus azaperone i.m., and butorphanol i.v. Etorphine resulted in hypertension and tachycardia in immobilized rhinoceros on initial measurements. Over the 25-min study period, blood pressures and heart rate declined. Heart rates were slower, although the rhinoceros were still tachycardic, and blood pressures lower during the whole study period in animals immobilized with etorphine and azaperone compared with those that received only etorphine. Butorphanol administration resulted in lower arterial blood pressures and heart rates in etorphine-immobilized rhinoceros. In rhinoceros immobilized with etorphine and azaperone, heart rate slowed following administration of butorphanol i.v., although blood pressures remained unchanged. Azaperone reduced hypertension associated with etorphine immobilization, but animals remained tachycardic. Administration of butorphanol to etorphine/azaperone-immoblized rhinoceros lowered heart rate to values approaching normal resting levels without altering blood pressure.

Postinduction butorphanol administration alters oxygen consumption to improve blood gases in etorphine-immobilized white rhinoceros

“…The objectives of this study were to determine the effects of etorphine on respiration in immobilized rhinoceros and changes that occur following IV administration of butorphanol. Cardiovascular effects of etorphine and IV butorphanol in these study rhinoceros have been previously reported ( Buss et al 2016).…”

“…An alternative explanation for the improved arterial blood gases following butorphanol administration may be increased pulmonary perfusion and reduction in inequality rather than changes in oxygen consumption (Wagner 2008). However, heart rate and systemic blood pressure decreased in etorphine-immobilized rhinoceros following butorphanol administration, suggesting a decrease in cardiac output (Buss et al 2016).…”

Etorphine-Azaperone Immobilisation for Translocation of Free-Ranging Masai Giraffes (Giraffa Camelopardalis Tippelskirchi): A Pilot Study

“…Azaperone can reduce the hypertensive effects of the opioids thanks to its affinity to alpha1 receptors, which produces peripheral vasodilation and reduces mean arterial blood pressure. Since, in our study, etorphine and its side effects were immediately reversed with naltrexone, more research on the possible occurrence of hypotension in the awake giraffe would be needed [20,29].…”

“…It was higher than in alpha2-agonist-based protocols, as these are commonly reported to cause bradycardia [45]. Etorphine stimulates catecholamines release, which, in many species, results in tachycardia [20,42], whereas, in the only study described in giraffes where etorphine was not immediately reversed, heart rate did not increase [33]. In our study, etorphine was immediately reversed with naltrexone, and, as such, the physiological variables reported in this study were technically collected under the effect of solely azaperone, which does not directly influence cardiac frequency [20].…”

“…Azaperone is a butyrophenone tranquiliser that has been widely used as an adjunct to an opioid-induced chemical restraint. Azaperone has sedative, anti-anxiety, and mild muscle relaxant effects, and, due to its alpha1 antagonistic effect, induces vasodilatation that can counterbalance opioid hypertension [18][19][20][21]. Reports of adverse effects in wild ungulates, such as severe hypotension and extrapyramidal effects, are rare and thought to result from high intravenous doses in stressed animals [19,22].…”