Arterial oxygenation and acid-base status before and during oxygen supplementation in captive European bison (Bison bonasus) immobilized with etorphine-acepromazine-xylazine.

Chemical immobilization of captive European bison (Bison bonasus) is often required for veterinary care, transportation, or husbandry practices playing an important role in conservation breeding and reintroduction of the species. We evaluated the efficiency and physiological effects of an etorphine-acepromazine-xylazine combination with supplemental oxygen in 39 captive European bison. Animals were darted with a combination of 1.4 mg of etorphine, 4.5 mg of acepromazine, and 20 mg of xylazine per 100 kg based on estimated body mass. Arterial blood was sampled on average 20 min after recumbency and again 19 min later and analyzed immediately with a portable i-STAT analyzer. Simultaneously, heart rate, respiratory rate, and rectal temperature were recorded. Intranasal oxygen was started after the first sampling at a flow rate of 10 mL.kg-1.min-1 of estimated body mass until the end of the procedure. The initial mean partial pressure of oxygen (PaO2) was 49.7 mmHg with 32 out of 35 sampled bison presenting with hypoxemia. We observed decreased respiratory rates and pH and mild hypercapnia consistent with a mild respiratory acidosis. After oxygen supplementation hypoxemia was resolved in 21 out of 32 bison, but respiratory acidosis was accentuated. Bison immobilized with a lower initial drug dose required supplementary injections during the procedure. We observed that lower mean rectal temperatures during the immobilization event were significantly associated with longer recovery times. For three bison, minor regurgitation was documented. No mortality or morbidity related to the immobilizations were reported for at least 2 months following the procedure. Based on our findings, we recommend a dose of 0.015 mg.kg-1 etorphine, 0.049 mg.kg-1 acepromazine, and 0.22 mg.kg-1 xylazine. This dose reduced the need for supplemental injections to obtain a sufficient level of immobilization for routine management and husbandry procedures in captive European bison. Nevertheless, this drug combination is associated with development of marked hypoxemia, mild respiratory acidosis, and a small risk of regurgitation. Oxygen supplementation is strongly recommended when using this protocol.

Evaluation of Three Medetomidine-Based Anesthetic Protocols in Free-Ranging Wild Boars (Sus scrofa).

Three medetomidine-based drug protocols were compared by evaluating time courses, reliability and physiological effects in wild boars. A total of 21 cage-trapped wild boars (Sus scrofa) were immobilized using one of the following drug combinations; MTZ: medetomidine (0.2 mg/kg) + tiletamine-zolazepam (2.0 mg/kg), MK: medetomidine (0.15 mg/kg) + ketamine (5 mg/kg), and MKB: medetomidine (0.1 mg/kg) + ketamine (5.0 mg/kg) + butorphanol (0.2 mg/kg). Induction time, recovery time, and physiological variables were recorded and arterial blood gas analysis measured twice, before and after 15 min of oxygen supplementation (0.5-1.0 L/min). For reversal, 4 mg of atipamezole per mg of medetomidine was administered intramuscularly. The boars recovered in the cage and were released once ataxia resolved. The MK group had significantly longer recovery times (mean 164 min ± 79 SD) compared to the other groups. MKB elicited longer and incomplete induction compared to the other groups (mean induction time 20 min ± 10 SD), decreasing the efficiency of the capture and increasing the risk of hyperthermia. Both ketamine-based protocols required additional ketamine intramuscularly to prolong the anesthesia after 20-40 min from induction. Agreement between the pulse oximeter and the blood gas analyzer was low, with the pulse oximeter underestimating the real values of arterial oxyhemoglobin saturation, particularly at higher readings. Mild acute respiratory acidosis (PaCO2 45-60 mmHg) and mild to moderate hypoxemia (PaO2 69-80 mmHg) occurred in most boars, regardless of the treatment group but especially in the MKB group. The acid-base status improved and hypoxemia resolved in all boars during oxygen supplementation, with the PaO2 rising above the physiological reference range (81.6-107.7 mmHg) in many individuals. MK and MKB induced safe and reliable immobilization of wild boars for at least 20 min. Supplemental oxygen delivery is recommended in order to prevent hypoxemia in wild boars immobilized with the protocols used in the present study. Long and ataxic recoveries occurred in most animals, regardless of the protocol, but especially in the MKB group.

Comparison of two non-invasive arterial blood pressure monitoring techniques in brown bears (Ursus arctos).

Monitoring arterial blood pressure (BP), represents a more accurate evaluation of hemodynamics than heart rate alone and is essential for preventing and treating intra- and post-operative complications in wildlife chemical immobilization. The objectives of the study were to test the correlation between standard oscillometry and Korotkoff's technique in anesthetized free-ranging brown bears in Croatia and Scandinavia and to assess the blood pressure in both locations. Five bears were snared and darted with xylazine and ketamine in Croatia, and 20 bears were darted from a helicopter with medetomidine and tiletamine-zolazepam in Scandinavia. Blood pressure was simultaneously measured with both techniques every 5 minutes. Correlation between techniques, trends of BP variation, and the factors of the capture which likely influenced BP were assessed. Successful measurements of BP were achieved in 93% of all attempts with the Korotkoff's technique but in only 29% of all attempts with oscillometry. The latter method mostly provided lower values of BP compared to Korotkoff's technique in yearlings. Most bears showed a decreasing trend in systolic and mean BP over time, consistent between the two techniques. All bears were hypertensive: the auscultatory technique detected moderate to severe systolic hypertension in 25% and 84% of bears in Croatia and in Scandinavia, respectively, with significantly higher BP in subadults and adults compared to yearlings. Only Korotkoff's method resulted in a reliable and effective tool for BP assessment in brown bears. The anesthetic protocols used in the present study in association with the capture methods produced hypertension in all animals.

NON-INVASIVE BLOOD PRESSURE AND OTHER PHYSIOLOGICAL DATA IN CHEMICALLY IMMOBILIZED BROWN BEARS (URSUS ARCTOS).

Free-ranging brown bears (Ursus arctos) were snared and subsequently darted with a combination of xylazine-ketamine in Croatia (n = 5) or darted from a helicopter with a combination of medetomidine-tiletamine-zolazepam in Scandinavia (n = 20). Three adults and one yearling (1 year old) bear were captured in Croatia, with one adult being captured twice. The Scandinavian bears were divided into Group A (yearlings, n = 7) and Group B (subadults, n = 2 and adults, n = 11). The exertion time (time from activation of the trap or from the start of the helicopter chase to recumbency) and the induction time (time from darting to recumbency) were recorded. The rectal temperature (Tr) was measured as soon as possible after induction and then monitored at frequent intervals (varied between individuals) in immobilized bears. Blood pressure (BP) was measured with a non-invasive method (Korotkoff's technique) every 5 minutes. The heart rate (HR), respiratory rate (RR), and arterial haemoglobin oxygen saturation (SpO2) were recorded every 5 minutes. Reliability of the BP monitoring technique, trends of variation of the physiological variables, and the factors related to the capture were assessed. Both exertion and induction times were longer in Croatian bears than in Scandinavian bears. In Croatian bears, the Tr was either constant or slightly decreasing, with hyperthermia recorded in two individuals (Tr > 39.0° C). In Scandinavian bears, 17 of 20 individuals developed an initial hyperthermia. Four of five bears in Croatia and 17 of 20 bears in Scandinavia showed a decreasing trend in systolic and mean BP over time. According to the Korotkoff method, all bears were hypertensive (mean BP > 130 mmHg) with varying severity, and the systolic pressure was significantly lower in yearlings when compared to subadults and adults. Yearlings had significantly (p < 0.05) higher HR than subadults and adults, however there was no significant differences in RR, SpO2, and Tr between the age groups. All Croatian bears and 13 of 20 Scandinavian bears were moderately to severely hypoxemic (SpO2 < 90%). Further studies with simultaneous invasive and non-invasive (Korotkoff) BP monitoring techniques are required to confirm the accuracy of methods used in this study. The data presented here provides evidence of the physiological impact of different capture methods and chemical immobilization of brown bears in Croatia and Scandinavia.