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.

Comparison of xylazine and lidocaine effects for analgesia and cardiopulmonary functions following lumbosacral epidural injection in goats.

The present study was carried out in order to compare the effects of xylazine and lidocaine on analgesia and cardiopulmonary parameters following epidural injection in goats. Twelve healthy Small East African goats of both sexes (mean +/- SD; 15.6 +/- 1.9 kg body weight) were used. The goats were randomly assigned to two groups of five and seven animals. The first group (n = 5) was given 2% lidocaine-HCl at 4400 micrograms/kg body weight. The second group (n = 7) was administered 2% xylazine-HCl at 150 micrograms/kg body weight. All drugs were diluted in 5 ml of sterile water and were injected epidurally through the lumbosacral interspace with the injection taking over 20 s. Both drugs induced analgesia within 5 min. Signs of sedation, cardiopulmonary changes and lateral recumbency developed within 5-7 min after administration of epidural xylazine. Tail flaccidity and hind limb paralysis developed 3 min after epidural administration of lidocaine. The time from recumbency to regaining normal stance was 60 and 158 min for xylazine- and lidocaine-treated animals respectively. Xylazine induced adequate analgesia of the flank and perineum, which extended to the head and forelimbs. In contrast, lidocaine induced adequate bilateral flank and perineal analgesia extending up to the third thoracic vertebra. For both drugs, analgesia of the flank and perineum persisted for the entire 180-min observational period. Epidural injection of xylazine and lidocaine caused variable depression effects on the cardiopulmonary values but was not so low as to cause concern. It is concluded that lumbosacral epidural injection of xylazine at 150 micrograms/kg body weight in 5 ml of water for injection offers the most desirable sedation and analgesia of the flank and perineum. The longer duration of analgesia may be useful for postoperative analgesia and relief of continuous straining in goats.