The purpose of this study was to assess how commonly used anesthetic agents affected the cardiac conduction systems of healthy dogs, both with and without pre-existing electrocardiographic abnormalities, and to monitor ventilation and oxygenation in order to determine possible causes of ST-segment and T-wave changes during anesthesia. The clinical study involved 12 dogs, divided into two groups. In the first group, six dogs were premedicated with atropine sulfate, and anesthesia was induced intramuscularly with ketamine hydrochloride and xylazine hydrochloride mixture. In the second group, ketamine hydrochloride and xylazine hydrochloride mixture were also used for induction, but anesthesia was maintained with isoflurane and 100% oxygen. Electrocardiographic recordings were taken in both groups before anesthesia and every 10 minutes during anesthesia. No ECG abnormalities were detected in the sizes of the P, QRS, or T waves in the first group. In the second group, isoflurane did not cause arrhythmias, making it a suitable choice for geriatric dogs. However, animals with hypercapnia showed ST-segment and T-wave alterations throughout maintenance anesthesia, underscoring the significance of quickly resolving this condition with assisted or controlled breathing to avoid the development of severe arrhythmias.

Keywords: Isoflurane, Ketamine, Xylazine, Dogs and Intramuscular.