The present study was designed to compare the influence of increased dose of dexmedetomidine and addition of fentanyl on the course of anaesthesia produced by dexmedetomidine-midazolam-ketamine combination in dogs. A prospective randomized blinded study was conducted on 12 client owned adult mixed breed dogs of either sex, divided into three groups. In the animals of group A, dexmedetomidine 10 μg kg-1 b.wt. and midazolam 0.4 mg kg-1 were administered simultaneously in the thigh muscles. In group B, dexmedetomidine 20 μg kg-1 and midazolam 0.4 mg kg-1 were administered. In the animals of group C dexmedetomidine 10 μg kg-1, midazolam 0.4 mg kg-1 and fentanyl 4 μg kg-1 were administered. Ten minutes later, ketamine was administered I.V. in all the groups to induce anaesthesia. Excellent muscle relaxation was observed up to 30 min in groups A and B and up to 75 min in group C. Pedal reflexes were abolished up to 45 min in groups A and B and up to 75 min in group C. Only 25% animals in group A permitted intubation, but intubation could be performed in all the animals of groups B and C. Weak time and down time were significantly (p<0.05) shorter in group B than in group A. Sternal recumbency time was significantly (p<0.05) longer in group B as compared to groups A and C but standing recovery time was significantly (p<0.05) shorter in group C as compared to groups A and B. Heart rate decreased significantly (p<0.05) in groups B and C but MAP (Mean Arterial Pressure) remained unchanged. In group A heart rate did not change significantly but MAP showed significant (p<0.01) decrease. Respiratory rate decreased significantly (p<0.05) in groups A and B but SPO2 (Saturated Oxygen) was maintained near the base line in all the groups. It was concluded that dexmedetomidine (10 μg kg-1) -midazolam (0.4 mg kg-1)-ketamine combination produced anaesthesia for 45 min. Increasing the dose of dexmedetomidine to 20 μg kg-1 did not offer any advantage, however, addition of fentanyl (4 μg kg-1) not only increased the duration of anaesthesia up to 60 min but also facilitated the recovery without additional adverse side effects.
K.M. Santosh, Amarpal , R.A. Ahmad, P. Kinjavdekar, H.P. Aithal and A.M. Pawde, 2012. Effect of Increased Dose of Dexmedetomidine Vis-à-vis Addition of Fentanyl on Clinical and Cardio-respiratory Actions of Dexmedetomidine-midazolam-ketamine Anaesthesia in Dogs. Asian Journal of Animal Sciences, 6: 51-64.