MVSc

An attempt was made to assess the efficacy of ephedrine as a reversing
agent in comparison with the known antagonists combination, yohimbine and
4-AP in xylazine-ketamine anaesthesia in rabbits.
The study was conducted in thirty two NewZealand White rabbits divided
into four groups of eight each. All the four groups (C, Tj , T2 and T3) were
anaesthetized with 5 mg/kg xylazine and 50 mg/kg ketamine administered
intramuscularlyat 15 min. interval. Group 'C' served as control, groups Tj , T2
and T3 served as treatments. In the middle of anaesthesia i.e., 30 min. after
induction of anaesthesia, group T 1 received yohimbine and 4-AP combination
(0.125 mg/kg and 0.2 mg/kg respectively IN), group T2 were given ephedrine
(10 mg/kg IN) and group T 3 received with ephedrine (20 mg/kg IN).
The anaesthetic parameters like the sequence and time of disappearance
and reappearance of righting, corneal, palpebral, ear-twitch and hind limb pedal
reflexes, duration of anaesthesia, arousal and recovery time were observed for all
groups. The rectal temperature, pulse rate and respiration rate were recorded at 0,
5, 10, 20, 30, 45, 60, 75, 90, 120, 150 min. during anaesthesia and also after
complete recovery. Haemogram was also studied before, during and also after
complete recovery from anaesthesia. The sequence and time of disappearance of
reflexes are as follows. Righting reflex was the first to disappear (1.4 min.)

followed by hindlimb pedal, corneal, palpebral and ear-twitch reflexes disappeared
at 3.7, 4.5 and 4.6 min. respectively after ketamine administration in all the four
groups. The mean time for disappearance of aforesaid reflexes showed no
significant variation among the different groups as the same anaesthetic schedule
was adopted for all the groups. Animals regained consciousness with the onset of
Zwangsnagen reflex, followed by reappearance of corneal, palpebral, ear-twitch
and hindlimb pedal reflex. Time for appearance of Zwangsnagen, corneal,
palpebral and ear-twitch reflexes were significantly reduced in treatment groups
when compared to control and there was no significant difference between
treatment groups for these parameters. Time for reappearance of hindlimb pedal
reflex was significantly shorter for group T3 when compared to groups Tl and
In companson with control group (60.6 min.) the mean duration of
anaesthesia was significantly reduced for treatment groups Tb T2 and T3 (33.6,
34.2 and 31.1 min. respectively). This decrease was significantly greater in T3
when compared to T 1 and T 2. Statistical analysis showed no significant
di fference between T 1 and T 2 in duration of anaesthesia.
All the four groups differ significantly from each other in the arousal and
recovery time. Shortest arousal time was recorded in T 1 group (9.1 min.)
followed by T3 (21.3 min.) and T2 (35.5 min.). Arousal time in control group was
103.85 min. The duration of time taken for recovery was greater for control group

(86.9 min.) followed by groups Tl and T2 (65.4 and 56.0 min. respectively).
These values were found to be significantly shorter for the group T 3 (41.5 min.).
The rectal temperature, pulse and respiration rates were significantly
decreased below normal values during xylazine-ketamine anaesthesia. These
parameters were found to be increased significantly after administration of
reversing agents in all treatment groups when compared to control group. The
study of haemogram showed that Hb, PC V, total RBC and total leucocyte counts
were significantly decreased during anaesthesia. These haematological changes
were completely reversed by administration of reversing agents in treatment
groups. From the results of the present study it could be concluded that ephedrine
can be used as an alternative to yohimbine and 4-AP combination in reversing the
anaesthesia produced by xylazine-ketamine combination in rabbits.