Evaluation of Clinico-physiological Effects of Ketamine Alone and in Combination with Dexmedetomidine or Butorphanol in Atropinized Dogs

Background: Ketamine is rarely used alone because of its association with poor muscle relaxation, tachycardia, catalepsy or muscle rigidity and therefore commonly used in combination with alpha 2 agonist or opioid to minimize the untoward effects. The aim of the present anaesthetic study was to evaluate the clinico-physiological effects of ketamine alone and in combination with dexmedetomidine or butorphanol for inducing adequate anaesthesia in dogs. Methods: The present anaesthetic study was conducted on 18 (eighteen) healthy dogs of either sex and randomly divided into three groups (K, DK and BK) with six animals in each group. Atropine sulphate @ 0.04 mg/kg was administered intramuscularly 15 minutes prior to anaesthetic study to all the animals. In group K, ketamine HCl alone was administered @ 5 mg/kg by slow i/v and kept as control. In group DK and BK, after administration of atropine sulphate 15 minutes later dexmedetomidine @ 10 mu g/kg i/m and butorphanol @ 0.2 mg/kg i/m were administered respectively. Ten minutes later ketamine HCl was administered @ 5 mg/kg slowly intravenously in both group DK and BK to induce surgical stage of general anaesthesia. The following clinical parameters were recorded viz., onset of sedation, onset of anaesthesia, degree of analgesia, extent of muscle relaxation, duration of anaesthesia and complete recovery. The physiological parameters (rectal temperature, heart rate and respiratory rate) were recorded before anaesthetic study at 0 min. and at 10 minutes after preanaesthetic administration and then at 10, 20, 40, 60, 90, 120 and 180 minutes after ketamine anaesthesia. All the data were analyzed using SPSS v 15.0 statistics software program and presented as mean +/- Standard Error. Result: The onset of sedation was quicker in group DK followed by group K and BK. Duration of anaesthesia and complete recovery in group DK was significantly (p<0.01) longer than in group K and BK. The degree of analgesia was excellent in group DK and good in group K and BK. The extent of muscle relaxation was excellent in group DK, good in group BK and was poor in group K. The physiological parameters showed transient changes which compensated and remained within normal range during the observation period. The above anaesthetic study suggests that ketamine in combination with dexmedetomidine or butorphanol can be safely used for inducing adequate anaesthesia in dogs. However, dexmedetomidine-ketamine can be used safely for longer duration of surgical procedures in dogs.