In search of balanced anesthesia: analyzing the effects of various injectable drug combinations in selected domestic animals

Professorial Chair Lecture

Centennial Professorial Chair Lecture

Place

College of Veterinary Medicine, University of the Philippines Los Banos

Date

7-2020

Abstract

The lecture explored the use of balanced anesthesia in veterinary ractice. The basic principles of anesthesia and background on studies on the use of tiletamine-zolazepam for balanced anesthesia in both domestic and wild animals is first discussed. The results of several studies local done on anesthetic combinations in three domestic animal species focusing on the duration of various phases of anesthesia, the cardiorespiratory effects of these anesthetic combinations, and their effects on the electrocardiogram were then analyzed in detail. The base anesthetic used was tiletamine-zolazeparm since this has superseded ketamine as the anesthethic of choice in domestic animals with the reclassification of ketamine as a schedule II regulated drug. Studies in cats have shown that the addition of xylazine significantly prolongs the effect of tiletamine-zolazepam but the addition of ketamine to tiletamine -zolazeparm does not have any significant effect except when both ketamine and xylazine are added to tiletamine-zolazepam which prolongs the duration of action to almost thwo hours. However, the combination of tiletamine-zolazepam, ketamine and xylazine also resulted in significant depression of the heart rate, respiratory rate and temperature. Higher doses of tiletamine-zolazepam whem combined with xylazine also resulted to agreater degree of depression of the vital signs. However, the user of propofol tended to cause an increase in the heart rate with a gradual return to pre-induction levels suggesting that the combination of the tiletamine-zolasepam and profol tended to cause as an increase in the heart rate, respiratory rate and temperature. Higher doses of tiletamine-zolazepam when combined with xylazine also resulted to a greater degree of depression of the vital signs. However, the use of propofol tended to cause an increase in the heart rate with a gradual return to pre-induction levels suggesting that the combination of tiletamine-zolazepam and profol maybe a better anesthetic combination although respiratory rates and temperature also dipped with this combination. The Sp02 levels tended to remain above 90 on average in all the combinations used suggesting adequate tissue oxygenation. In dogs, tiletamine-zolazepam alone tends to a result to a 'stormy' recovery since tiletamine is metabolized more slowly than zolazepam. Thus, it is important to produce a balanced anesthesia that would result to smoother recoveries. Romifidine has been shown to prolong the duration of tiletamine-zolazepam anesthesia although it also resulted in depression of vital sign except when only half the recommended dose of tiletamine-zolazepam is used. ECG abnormalities were also observed. In goats, tiletamine-solazepam alone did not result to the production of analgesia. Combining the tiletamine-zolazepam with xylazine has been shown to result in decreased cortisol levels 30 minutes after administration which is interpreted to mean that there is adequate pain in relief. However, the decrease in cortisol level is significantly lower when ketamine-xylazine combination is used leading one to conclude that this combination produces better antinociception. Although xylazine does prolong the duration of action tiletamine-zolasepam and ketamine, this also results to prolonged recovery times. Cardiorespiratory depression is also present and there is a tendency to wards the production of arrhythmias.

and xylazine when controlled

College

College of Veterinary Medicine (CVM)

Language

English

Pages/Collation

94 leaves

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