EVALUATION OF TWO MEDETOMIDINE-AZAPERONE-ALFAXALONE COMBINATIONS IN CAPTIVE ROCKY MOUNTAIN ELK (CERVUS ELAPHUS NELSONI)

Comparison of anesthetic effects of xylazine combined with alfaxalone or ketamine and maintained with isoflurane in captive Formosan Reeve's Muntjac (Muntiacus reevesi micrurus)

Formosan Reeve's muntjac is a Cervidae species endemic to Southeast China and Taiwan. However, research on different anesthetic protocols, their effects, and their safety in Formosan Reeve's muntjac is limited. This study evaluated the effects of ketamine-xylazine (KX) and alfaxalone-xylazine (AX) administered via blow darts to nine muntjacs. Induction and recovery times as well as the quality were assessed by a blinded observer. Peripheral oxygen saturation (SpO2), heart rate, respiratory rate, and rectal temperature were recorded for at least 30 min. Tolazoline (4 mg/kg) was used post-procedure to reverse xylazine's effects. The mean doses were 4.68 ± 2.18 mg/kg for ketamine and 3.22 ± 1.33 mg/kg for xylazine in the KX group. In the AX group, the mean doses were 4.38 ± 0.31 mg/kg for alfaxalone and 1.19 ± 0.26 mg/kg for xylazine. The median induction times were 339.5 s (range 180.0-375.0) for KX and 125.0 s (range 71.0-334.0) for AX, with both groups scoring 3.0 for induction quality. The recovery times were 507.5 s (range 266.0-1081.0) for KX and 243.0 s (range 92.0-480.0) for AX, with recovery scores of 2.3 and 3.0, respectively, showing no significant difference. Hypoxemia (SpO2 < 90%) was more severe in the KX group when compared to the AX group (SpO2 > 92%), and rectal temperatures were higher in the former during the first 15 min. Heart and respiratory rates showed no significant differences between groups. Our findings demonstrate that both anesthetic combinations achieve reliable induction and satisfactory recovery in Formosan Reeve's muntjac, with the ketamine-xylazine combination causing a more profound hypoxemia post-induction compared to the alfaxalone-xylazine combination.

EFFICACY OF TOLAZOLINE AND VATINOXAN IN REDUCING ADVERSE EFFECTS OF BUTORPHANOL-AZAPERONE-MEDETOMIDINE IMMOBILIZATION IN ROCKY MOUNTAIN ELK (CERVUS CANADENSIS)

A mixture of butorphanol, azaperone, and medetomidine (BAM) is frequently used for immobilization of North American hoofstock. Common adverse effects include respiratory depression, hypoxemia, and bradycardia. In this nonblinded crossover study the efficacy of two a-2 adrenergic antagonists, tolazoline and vatinoxan, were evaluated in alleviating adverse effects of BAM in Rocky Mountain elk (Cervus canadensis). Early administration of these antagonists was hypothesized to cause an increase in heart rate, respiratory rate, partial pressure of oxygen (PaO2) and hemoglobin oxygen saturation (SpO2), as well as reduction in mean arterial blood pressure without affecting sedation levels. Eight captive adult female elk were immobilized on three separate occasions at least 14 d apart with 0.15 mg/kg butorphanol, 0.05 mg/kg azaperone, and 0.06 mg/kg medetomidine. Tolazoline (2 mg/kg IM), vatinoxan (3 mg/mg medetomidine IV) or sterile saline (2 ml IM) were administered 20 min postinduction. The BAM caused hypoxemia, bradycardia, and moderate hypertension, and because of the severe hypoxemia observed, all animals received intratracheal oxygen throughout immobilization. Heart rate, respiratory rate, rectal temperature, SpO2, PaO2, and systolic, diastolic, and mean arterial blood pressure were monitored every 5 min throughout the immobilization. Intramuscular tolazoline caused a brief but significant drop in mean arterial pressure compared with controls and a brief but nonsignificant increase in heart rate. Vatinoxan caused a significant drop in blood pressure and a brief significant increase in heart rate. Changes in respiratory rates and PaO2 were not observed with either antagonist; however, all animals received oxygen, which may have influenced this result. The depth of sedation was unchanged after administration of either drug.

Sedative and cardiorespiratory effects of intranasal atomized alfaxalone in Japanese White rabbits

OBJECTIVE

To investigate the sedative and cardiorespiratory effects of intranasal atomization (INA) of alfaxalone using a mucosal atomization device in Japanese White rabbits.

STUDY DESIGN

Randomized, prospective, crossover study.

ANIMALS

A total of eight healthy female rabbits, weighing 3.6-4.3 kg and aged 12-24 months.

METHODS

Each rabbit was randomly assigned to four INA treatments administered 7 days apart: Control treatment, 0.15 mL 0.9% saline in both nostrils; treatment INA0.3, 0.15 mL 4% alfaxalone in both nostrils; treatment INA0.6, 0.3 mL 4% alfaxalone in both nostrils; treatment INA0.9, 0.3 mL 4% alfaxalone in left, then right, then left nostril. Sedation was scored 0-13 using a composite measure scoring system for rabbits. Simultaneously, pulse rate (PR), respiratory rate (f_R), noninvasive mean arterial pressure (MAP), peripheral hemoglobin oxygen saturation (SpO₂) and arterial blood gases were measured until 120 minutes. The rabbits breathed room air during the experiment and were administered flow-by oxygen when hypoxemia (SpO₂ <90% or PaO₂ <60 mmHg; 8.0 kPa) developed. Data were analyzed using the Fisher's exact test and the Friedman test (p < 0.05).

RESULTS

No rabbit was sedated in treatments Control and INA0.3. All rabbits in treatment INA0.9 developed loss of righting reflex for 15 (10-20) minutes [median (25th-75th percentile)]. Sedation score significantly increased from 5 to 30 minutes in treatments INA0.6 and INA0.9 with maximum scores of 2 (1-4) and 9 (9-9), respectively. f_R decreased in an alfaxalone dose-dependent manner and one rabbit developed hypoxemia in treatment INA0.9. No significant changes were observed in PR and MAP.

CONCLUSIONS AND CLINICAL RELEVANCE

INA alfaxalone resulted in dose-dependent sedation and respiratory depression in Japanese White rabbits to values considered not clinically relevant. Further investigation of INA alfaxalone in combination with other drugs is warranted.