Clinical and Hematological Effect of Constant Rate Infusion of Ketamine Alone and Ketamine-dexmedetomidine Combination on Isoflurane Anesthesia in Horses

Background: Anaesthetic management of horses for a successful surgery is of utmost importance but a risky procedure than other companion animals. Peri-aneasthetic morbidity and mortality in horses could be alarming if proper combinations of drugs were not used. Balanced anaesthetic combinations are being explored by various authors to find safer combinations.Therefore current study was planned to evaluate the effect of CRI of ketamine alone and ketamine-dexmedetomidine combination for isoflurane anesthesia in horses. Methods: Twenty four clinical cases of horses were randomly divided into three groups S, D and DK, having eight animals in each. Xylazine (1 mg/kg) and butorphanol (0.05 mg/kg) were given intravenously for premedication and ketamine (2 mg/kg) and midazolam (0.2 mg/kg) were used for induction of anesthesia. Normal saline (1000 ml/hour), ketamine alone (2 mg/kg/hr), ketamine (2 mg/kg/hr) and dexmedetomidine (2 µg/kg/hr) combination were given as CRI in groups S, K and KD, respectively. Thiopentone sodium (200 mg bolus, 5%) was given as fast intravenous to facilitate endotracheal intubation in some of the cases. Anesthesia was maintained with isoflurane in oxygen and anesthetic efficacy was evaluated based on clinical and haematological parameters. Result: Overall quality of sedation, muscle relaxation, response to surgical stimuli, quality of intubation, anesthetic depth and quality of recovery was significantly (p less than 0.05) better in group KD. Down-time (min) and duration of anesthesia were non significantly less in group KD. CRI of ketamine and dexmedetomidine combination was having significant (p less than 0.05) thiopentone sodium and isoflurane sparing effect. Heart rateand RR, did not show any significant variation among groups but rectal temperature was significantly low in KD group than groups S and K. CRI of ketamine-Dexmedetomidine combination produced a better quality of anesthesia and significant thiopentone sodium and isoflurane sparing effect thus was found suitable for anesthesia of horses.