Reversal of sedative and clinicophysiological effects of epidural xylazine and detomidine with atipamezole and yohimbine in buffaloes (Bubalus bubalis)

The Clinical Effect of Xylazine Premedication in Water Buffalo Calves (Bubalus bubalis) Undergoing Castration under General Anaesthesia

Simple Summary

Castration is used to improve the management of buffalo calves and their meat quality. Despite the growing interest in livestock welfare, water buffaloes have not been studied as frequently as other species. General anaesthesia produces complete unconsciousness, insensitivity to pain and muscle relaxation. The quality and safety of general anaesthesia may be improved using sedatives prior to the induction of general anaesthesia. The aim of this study was to evaluate the effect of two different intramuscular doses of xylazine for premedication, followed by ketamine induction, in water buffalo calves undergoing isoflurane maintenance anaesthesia for routine castration surgery. Based on the results obtained, we can conclude that both protocols are safe for buffalo castration, but the higher dose protocol is recommended for buffalo orchiectomy.

Abstract

Castration is one of the most frequently performed surgical procedures in livestock. All methods of castration are associated with a significant degree of pain, affecting the patients’ welfare. Limited information on species-specific protocols in buffaloes is available. Considering the importance of this species and the scarcity of reports available, the objective of this study was to evaluate the effects of two different intramuscular doses of xylazine for premedication in water buffalo calves undergoing isoflurane maintenance anaesthesia for routine castration surgery. Twenty clinically healthy male water buffaloes undergoing bilateral orchiectomy were randomly assigned to two groups of 10 animals each: Group 1 was premedicated with xylazine 0.1 mg/kg bw i.m. and Group 2 was premedicated with xylazine 0.15 mg/kg bw i.m. Anaesthesia was induced by ketamine (2 mg/kg bw i.v.) and maintained with isoflurane-oxygen-air in both groups. The HR, RR, presence/absence of ataxia, sedation, depth of anaesthesia, muscle relaxation status, response to acoustic and tactile stimuli, eyelid reflex, extent of salivation and stimulus were evaluated every 5 min. Both protocols provided consistent sedation and were safe. Faster and more satisfactory sedation was recorded when xylazine was administered at 0.15 mg/kg bw i.m., leading us to recommend this dose for buffalo orchiectomy.

Reversal of epidural xylazine in Egyptian water buffalo (Bubalus bubalis) with atipamezole

The reversal of epidural xylazine, induced with IV atipamezole was evaluated in 15 buffaloes. Atipamezole at different dose rates (5, 10 and 15 µg/kg) injected 30 minutes after epidural xylazine provoked visible signs of arousal shortly after inection in all buffaloes without any side effects. The mean arousal times were 4.8±0.84 min, 2.4±0.24 min and 2.0±0.00 min while the mean total recovery times were 61.0±2.6 min, 33.0±3.7 min and 32.0±4.3 min following doses of 5, 10 and 15 µg/kg atipamezole respectively. The heart, respiratory and ruminal rates were mildly influenced. Overall, the IV atipamezole at a dose rate of 10 µg/kg was found effective and satisfactory for reversing the analgesic, sedative and cardiopulmonary depression effects induced by epidural xylazine administration in buffaloes.

The analgesic effects of intrathecal xylazine and detomidine in sheep and their antagonism with systemic atipamezole

OBJECTIVE

To evaluate the analgesic and adverse side effects of intrathecal (IT) xylazine (XYL) and detomidine (DET) and the subsequent effects of two doses of intravenous (IV) atipamezole (ATI).

STUDY DESIGN

Prospective, randomized, cross-over.

ANIMALS

Five adult healthy female sheep with mean body mass of 55 +/- 2.3 kg. Material and methods Each sheep underwent four treatments: 1) 50 microg kg(-1) XYL IT and 5 microg kg(-1) ATI IV, 2) 50 microg kg(-1) XYL IT and 2.5 microg kg(-1) ATI IV, 3) 10 microg kg(-1) DET IT and 5 microg kg(-1) ATI IV, 4) 10 microg kg(-1) DET IT and 2.5 microg kg(-1) ATI IV. Pain threshold (TH) was tested by applying pulsed and stepwise incremental direct current to the skin overlying the pastern. The current at the point of foot lift was recorded as the TH. Heart rate (HR), mean arterial pressure, arterial oxygen (PO(2)) and carbon dioxide (PCO(2)) tensions were monitored. Outcomes were derived as differences between baseline assessment and measurements after treatment. Two-way anova was used to analyse drug effects, treatment differences between groups were examined with an F-test or Wilcoxon's rank sum test in case of non-parametric data distribution. p was set at 0.05.

RESULTS

Both drugs increased the pain TH, caused small increases in PCO(2), and small decreases in HR, the latter was only significant for XYL recipients. Xylazine produced a significantly higher TH, more rapidly and for longer than DET. Atipamezole only significantly affected PaCO(2) in the XYL group 2. The pain TH was not affected in either group after IV ATI.

CONCLUSIONS

At the doses used, IT XYL, and to a lesser extent DET, induced pastern analgesia. Atipamezole 5 microg kg(-1) IV antagonized some side effects without affecting analgesia.

CLINICAL RELEVANCE

Intrathecal XYL may be useful as an analgesic in sheep. Its safety is increased because IV ATI antagonizes side effects, but not analgesia.

Effect of caudal epidural xylazine on intraoperative distress and post-operative pain in Holstein heifers

OBJECTIVE

To compare the effects of caudal epidural xylazine versus saline on tolerance of paravertebral nerve block and flank surgery and on post-operative pain in heifers used for a veterinary student training laboratory.

STUDY DESIGN

Randomized controlled prospective study.

ANIMALS

Fourteen one-year-old, nongravid, healthy Holstein heifers, weighing 360 +/- 5 kg.

METHODS

Xylazine (0.05 mg kg(-1)) or 0.9% saline (5 mL) was injected using a caudal epidural technique to seven heifers undergoing a flank surgery. Nerve block of the right paravertebral fossa was performed using equal parts of lidocaine 2% and bupivacaine 0.5%. Heart and respiratory rates, rectal temperature, rumination frequency, and appetite were recorded before and at 4, 8, and 24 hours after surgery. Scores were recorded for: tolerance of local anesthesia injections (pre-operatively), sedation, ataxia and distress (intraoperatively, every 30 minutes), and pain (4, 8, and 24 hours post-operatively).

RESULTS

The animals reaction to local anesthetic injection was judged to be less in the xylazine group by both an experienced observer (p<0.001) and student surgeons (p<0.01). The xylazine group required less local anesthetic (82.9 +/- 13.8 mL) versus the saline group (108.4 +/- 19.6 mL, p=0.035). Intraoperatively, xylazine heifers were more sedated at all times (p-values from <0.001 to 0.017), were more ataxic for the first 1.5 hours (p-values from <0.001 to 0.026), and lower in distress at all times (p-values from <0.001 to 0.007). No difference in post-operative pain or physiologic variables was found, except immediately post-operatively, rectal temperature was higher in the xylazine group (39.5 +/- 0.3 degrees C) than in the saline group (38.6 +/- 0.2 degrees C, p<0.001).

CONCLUSION AND CLINICAL RELEVANCE

Compared with epidural saline, caudal epidural xylazine reduced distress of anesthetic injection and surgical manipulation in heifers and an improvement in animal well-being was apparent. This effect may have been as a result of sedation. Pre-operative epidural xylazine did not appear to improve post-surgical analgesia in our study.

Comparison of the effects of atipamezole and tolazoline on analgesia, cardiopulmonary and rectal temperature changes induced by lumbosacral epidural injection of medetomidine in goats

The present study was carried out in order to compare the reversing effects of alpha(2)-adrenergic receptor antagonists, atipamezole and tolazoline on analgesia, cardiopulmonary depression and rectal temperature changes induced by epidural administration of medetomidine in goats. Eight clinically healthy, small East African goats of both sexes weighing between 12 and 17kg (mean 14.4+/-1.8kg) were used in this study. The animals were randomly divided into two groups of four animals. The first group was given 20µg/kg medetomidine followed by intravenous (IV) administration of 80µg/kg atipamezole, 30min after the initial injection. The second group was given same treatment for medetomidine as group one but followed by IV administration of 2.2mg/kg tolazoline, 30min after the initial injection. In both treatment groups, medetomidine was administered epidurally through the lumbosacral interspace. Analgesia of the flank and perineum was evaluated at every 10min intervals up to 60min. The cardiopulmonary and rectal temperature values were monitored and recorded at every 5min interval up to 60min. In both groups, lumbosacral epidural injection of medetomidine induced generalised analgesia, variable cardiopulmonary depression effects and non-significant changes on rectal temperature. These changes developed as early as 5min and continued until alpha(2)/alpha(1) antagonists were administered. Intravenous administration of alpha-adrenergic receptor antagonists; atipamezole and tolazoline reversed analgesia, cardiopulmonary and rectal temperature changes induced by lumbosacral epidural injection of medetomidine in goats. However, atipamezole appeared to be superior (P<0.05) to tolazoline. From this study, it was concluded that IV administration of 80µg/kg atipamezole was better than 2.2mg/kg tolazoline in reversing analgesia and cardiopulmonary depression effects induced by lumbosacral epidural injection of medetomidine in goats. This indicates the superiority of atipamezole to tolazoline as an antidote for medetomidine induced effects in goats.

Analgesic, behavioural and cardiopulmonary effects of epidurally injected medetomidine (Domitor) in goats

This study was carried out in order to evaluate the analgesic, sedative, immobilizing and cardiopulmonary effects of medetomidine in goats after lumbosacral epidural injection of three (10, 20 and 30 micrograms/kg body weight) doses. The volume of the injection for all three medetomidine doses was 5 ml in sterile water. Seventeen clinically healthy, Small East African goats of either sex and weighing between 12 and 22 kg (mean +/- SD; 14.8 +/- 2.5 kg body weight) were used. The animals were randomly assigned to two groups. Seven goats were used for evaluating analgesic, behavioural and cardiopulmonary effects while 10 were used for experimental surgery. The cardiopulmonary values and rectal temperature were determined and recorded at time 0 (preinjection) and at 5, 10, 15, 20 and 30 min, and thereafter at 15-min intervals up to 180 min after injection. Analgesia of the flank and perineum was determined at time 0 (preinjection) and at 5, 10, 15, 30, 60, 120 and 180 min using a scoring system. The spread of analgesia to the thorax, neck, forelimbs and head was also determined and recorded. The onset and duration of lateral recumbency was noted and recorded. Medetomidine at the given doses induced variable cardiopulmonary depression, which was not detrimental to the animals. All three doses (10, 20 and 30 micrograms/kg) of medetomidine induced adequate analgesia of the flank and perineum. Analgesia extended to the thorax, forelimbs, neck and head. The duration of lateral recumbency was 136 and 166 min for the 20 and 30 micrograms/kg medetomidine doses, respectively. The duration of lateral recumbency was not determined for the animal given 10 micrograms/kg medetomidine. Signs of sedation (lowering of the head, drooping of the lower lip, partial to complete closure of the eyes and salivation) were noted after administration of all three doses. It can be concluded from this study that all three doses induced adequate analgesia of the flank and perineum. Surgical analgesia of the flank of goats was achieved after lumbosacral epidural administration of 20 micrograms medetomidine/kg, diluted in 5 ml of sterile water. Surgery was not performed with the other doses (10 and 30 micrograms/kg) of medetomidine.