MVSc

The experiment was conducted to find out the synergistic effect of xylazine with tiletamine – zolazepam anaesthesia and to study the reversing action of aminophylline in tiletamine – zolazepam – xylazine anaesthesia. The study was conducted in 5 batches of 6 dogs each. The first group of animals (c) received tiletamine – zolazepam at the rate of 5 mg/kg I/V. The second group (T1) received xylazine (0.5 mg/kg I/M) and 15 minutes later, tiletamine – zolazepam (2.5 mg/kg I/V). The third group (T2) received xylazine (I mg/kg I/M and 15 minutes later, tiletamine zolazepam (1.25 mg/kg I/V) The treatment schedule that resulted in a greater duration of anaesthesia ie, T2, was chosen for studies in the subsequent groups. The fourth (T3) and fifth (T4) group of animals received the anaesthesia scheduled as in T2, and in the middle of anaesthesia ie. after 8 minutes, the animals were given aminophylline intravenously at the dose rate of 20 mg/kg and 40 mg/kg respectively.
The anaesthetic parameters like the time of recumbency, time of appearance and disappearance of skin clamp and tail clamp anaesthesia, time of regaining of righting reflex and sternal recumbency, and the time for standing and walking were recorded for all treatments. The rectal temperature, pulse rate and respiration rate were recorded at 0, 5, 10, 15, 20, 30, 45, 60, 90, and 120 minutes after administration of anaesthetic. The haemogram was also studied before, during and after anaesthesia.
All the animals came to recumbency after the injection of tiletamine – zolazepam within a mean time of 10 seconds. The time of recumbency and the time of appearance of tail clamp and skin clamp anaesthesia showed no significant difference between the different groups. The time of disappearance of tail clamp anaesthesia for the group C, T1 and T2 were 23.5, 20.2 and 18.6 minutes and for T3 and T4 were 14.2 and 15.7 minutes respectively. Time of disappearance of skin clamp anaesthesia for the groups C, T1, and T2 were 29.5, 23.3 and 22.7 minutes and for the groups T3 and T4 were 14.8 and 16.7 minutes respectively. The time of regaining of righting reflex for the groups C, T1 and T2 were 23.8, 28.8 and 35.3 minutes and for T3 and T4 were 24 and 24.8 minutes respectively. The time of sternal recumbency were 42.8, 33.2 and 43.3 minutes for the groups C, T1 and T2 and 28.5 and 29.8 minutes for T3 and T4 respectively. All these values showed significant difference between C and T2 and also between T2 and T3 and T4. The mean time for standing and walking showed significant difference only between the control group (73.3 and 78.2 minutes respectively) and T2 (47.5 and 48.3 minutes respectively), but not between T2, T3 and T4.
The duration of skin clamp anaesthesia, tail clamp anaesthesia and the recovery time were significantly shorter for the group T3 when compared to T2. The most noticeable behavioural characteristics during recovery were rhythmic head and neck rocking, whining and paddling and these were present only in the control group. There was no significant difference between the groups in the rectal temperature during anaesthesia except at 10 minutes time, when the decrease in temperature was greater for T3 and T4 when compared to T2. There was no significant difference in the pulse rate also between the group throughout anaesthesia, with an exception only at 15 minutes when the increase in pulse rate was greater for C than for T2. The decrease in respiratory rate was significantly greater for T2 when compared to C from 5 to 30 minutes during anaesthesia. The haemogram showed no significant difference between the groups during anaesthesia.
From the results obtained, it could be concluded that
1. the combination of xylazine (I mg/kg I/M) and tiletamine – zolazepam (1.25 mg/kg I/V) could be used to produce satisfactory, short – term anaesthesia in dogs and
2. aminophylline at a dose rate of 20 mg/kg I/V could be used to reverse anaesthesia produced by tiletamine – zolazepam – xylazine combination.