A COMPARATIVE STUDY ON THE USE OF KETAMINE AND THIOPENTAL AS INDUCTION AGENTS FOR ISOFLURANE INHALATION ANAESTHESIA IN DOGS
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2012-07
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SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA
Abstract
ABSTRACT :
The present clinical study was carried out on 12 dogs between 1 year to 10 years of age presented for ovariohysterectomy and castration. These dogs were randomly divided into two groups comprising of six animals in each group. All the dogs were uniformly premedicated.
In the six dogs of group-I, anaesthesia was induced by intravenous administration of Ketamine at the rate of 5 mg/kg body weight. In dogs of group II, Thiopental sodium was used as an intravenous anaesthetic induction agent at the dose of 10 mg/kg body weight as a 2.5 per cent solution. Immediately after induction, the dogs of two groups were intubated and anaesthesia was maintained with 1.5% to 2% inhalation of Isoflurane during the entire surgical procedure. The anaesthetic effects like induction of anaesthesia, duration of anaesthesia, recovery time and physiological parameters like temperature, heart rate, respiratory rate and Electrocardiograph (ECG) were studied before induction, during anaesthesia and after recovery from anaesthesia. Haematological parameters like TEC, TLC, Hb, PCV, DLC and biochemical parameters like AST, ALT, BUN and Serum Creatinine were recorded before induction, during anaesthesia and after recovery. The results of the present study indicated that there was a significant difference between the induction time of Ketamine and thiopentone. Thiopentone differed significantly when compared to the use of ketamne as the induction agent where the induction time ranged from 50 to 128 seconds (mean 89.66 ± 6.74). It was also observed that while Ketamine at 5 mg/kg body weight induced anaesthesia deep enough to allow intubation in only four out of the six dogs. In the other two dogs, an additional dose of 1 mg/kg body weight was necessitated. Thiopentone uniformly induced anaesthesia deep enough to allow intubation in all the six dogs at the dose of 10 mg/kg of body weight as a 2.5 per cent solution, The anaesthetic protocols studied produced satisfactory and safe deep surgical anaesthesia in both the groups of dogs. However, in the dogs of groups I, maintenance of anaesthesia necessitated a concentration of 2% isoflurane in oxygen. The concentration of isoflurane was increased from 1.5% to 2 % as soon as the dogs showed some sluggish response to pedal and tail clamp reflexes, while in the dogs of group II of the six dogs necessitated only 1.5% isoflurane. In all the dogs of the two groups, recovery from anaesthesia was found to be smooth and uneventful. The dogs of group II recovered earliest from anaesthesia when compared to the group I. As far as the physiological parameters were concerned, the results showed that in all the dogs of groups I and II, anaesthesia resulted in a significant drop in the rectal temperature during and after anaesthesia as compared to the before induction. Although the heart rates between the groups were found to be differ from each other, they were still well within the normal range and hence were considered in consequential. The results showed that Ketamine induction caused a significant reduction of the respiratory rate in the dogs of group I during the maintenance of anaesthesia. The respiratory rate returned to normal as the dogs recovered from anaesthesia. Since these parameters caused no complications and since they returned to normalcy soon, the changes were considered to be clinically acceptable. The recovery from anaesthesia in all the six dogs of group II was considered good. In the dogs of group I, good recovery in four dogs and fair recovery in two dogs was recorded. Haematological examination revealed that there were no significant differences in the various parameters like TEC, TLC, Hb, PCV, DLC in any of the two groups and the three intervals. This underscored the fact that all the anaesthetic protocols studied were safe and uneventful as far as these observations were concerned. The results of the present clinical study clearly revealed in all the dogs of the two groups that the various biochemical parameters studied, i.e., AST, ALT, BUN and Serum Creatinine remained within normal limits. Hence, this also conclusively proved that the two anaesthetic protocols studied were safe and did not result in any damage to the heart, liver and kidneys during the anaesthetic period. Electrocardiographic studies in the dogs of both the groups revealed no abnormalities in the sizes of P, QRS or T- waves, no changes in the cardiac axes and no arrhythmias of any kind in any dog of any of the groups. From the results of the present study, it was concluded that both the anaesthetic protocols produced satisfactory deep surgical anaesthesia in dogs. While 2.5% thiopentone was found to have produced sufficiently deep anaesthetic induction to allow
intubation at the uniform dose of 10 mg/kg, Ketamine was found to be effective at 5 mg/kg in 4 dogs and two dogs required 6 mg/kg i/v. When anaesthesia was induced with thiopentone sodium @ 10 mg/kg body weight, the dogs could be maintained at 1.5% isoflurane inhalation in oxygen. When anaesthesia was induced with Ketamine (5 to 6mg/kg, i/v), maintenance of anaesthesia was best done with 2% Isofluorane. Both the anaesthetic protocols studied in the present study resulted in minimal, clinically insignificant changes in the various physiological, biochemical and electrocardiographic parameters.
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