• Journal of Veterinary Clinics
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• v.32 no.4
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• pp.308-312
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• 2015

This study was aimed to evaluate the effects of tramadol hydrochloride on the minimum alveolar concentration of isoflurane ($MAC_{ISO}$) in dogs. Six healthy, female German shepherd dogs (aged 1-2 years) were used in this study. Anesthesia was induced by mask induction and maintained with isoflurane in oxygen. Mechanical ventilation maintained the end-tidal $CO_2$ partial pressure ($P_{ET}CO_2$) from 35 to 45 mmHg throughout the study. A baseline $MAC_{ISO}$ ($MAC_{ISO}B$) was determined starting 45 minutes after induction of anesthesia by clamping a pedal digit until gross purposeful movement was detected. After $MAC_{ISO}B$ determination, dogs received a tramadol loading dose of 3 mg/kg followed by a continuous rate infusion (CRI) of 2.6 mg/kg/h. The determination of $MAC_{ISO}$ after administration of tramadol ($MAC_{ISO}T$) began 20 min after the start of the CRI. Arterial blood pressure and heart rate were recorded continuously and arterial blood samples for blood gas analysis were collected at the end of the equilibration period. Mean ${\pm}$ SD values for the $MAC_{ISO}B$ and $MAC_{ISO}T$ were $1.33{\pm}0.04%$ and $1.23{\pm}0.04%$, respectively. The $MAC_{ISO}B$ decreased significantly by $7.5{\pm}0.2%$ (P < 0.05) after administration of tramadol. The mean heart rate and arterial blood pressure of six dogs were not changed significantly after tramadol administration. The blood gas levels remained constant during the study. In conclusion, tramadol could significantly reduce $MAC_{ISO}$ without depression of cardiorespiratory function. Thus, the use of tramadol on inhalation anesthesia with isoflurane in dogs can improve the stability of anesthesia and the quality of recovery.

• Journal of Veterinary Clinics
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• v.26 no.6
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• pp.539-546
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• 2009

The effect of hemorrhage on the electroencephalogram(EEG) was investigated in fifteen mixed-breed dogs anesthetized with ketamine, propofol and isoflurane. Animals were randomly allocated to three groups (n = 5) by anesthetic agents; group 1 (ketamine 5 mg/kg, IV), group 2 (propofol $156\;{\mu}g$/kg/min, IV) and group 3 (isoflurane 2.0% end-tidal concentration). Medetomidine ($40\;{\mu}g$/kg, IM) was used in all dogs as a preanesthetic agent. Recording electrode for EEG was positioned at CZ. EEG, heart rate, systolic/diastolic blood pressure, $pCO_2$, $pO_2$ and blood pH were measured before anesthesia, after anesthesia and after every bleedings. Three bleedings were accomplished by drawing blood through the femoral artery catheter at a rate of 7 ml/kg (10% of total blood volume) for 10 minutes. In the course of hemorrhage, a systolic/diastolic pressure continuously decreased in all groups. The $pCO_2$ values and heart rates were increased in all groups. The $pO_2$ values were most significantly increased in group 1 compared with those in other groups. The pH values were not significantly changed. On statistical analysis of EEG, there was no significant changes in group 1 and 3. But in group 2, band 3, 4 and 7 were significantly altered after 2nd and 3rd bleeding. Power alterations of band 3, 4 and 7 were thought to be related with hemorrhage over 20% of total blood volume in group 2. In conclusion, the regulation of infusion rate would be considered when a dog, anesthetized with propofol, bleed over 20% of total blood volume.