Clinical Studies on Glycopyrrolate, Diazepam -fentanyl and Xylazine – Pentazocine as Preanaesthetics to Propofol – Isoflurane Anaesthesia in Dogs

Abstract

The present study was conducted to evaluate and compare four different balanced anaesthetic protocol in clinical cases of dogs undergoing various surgical procedures. Sixteen client-owned dogs of different breeds, (5 Nondescripts, 4 Labrador, 2 Rottweilers, 2 German shepherds, 1 Pitbull, 1 American bully and 1 Doberman) of either sex (9 Males and 7 Females), of different age groups (4 months to 11 years range) suffering from various surgical affections were selected as the subject of the study. These animals were randomly divided into 2 groups and 4 subgroups. All animals were kept off feed for 12 hours and water was withheld for 3-6 hours before anaesthesia. Before administration of any anaesthetics the animals were left undisturbed for 1 hour. Sixteen canine patients were divided into 2 groups viz. X and D with eight animals in each, they were further divided into four sub groups X1, X2 and D1, D2 with four animals in each subgroup. In subgroup X1, as preanesthetic glycopyrrolate @ 0.005 mg/kg body wt. was administered, intramuscularly. After 15 minutes xylazine @ 0.5 mg/kg body wt. and pentazocine @ 2 mg/kg body wt. were administered, intramuscularly, one after the other, in separate syringes. In subgroup X2 glycopyrrolate @ 0.005 mg/kg body wt. was administered intramuscularly. After 15 minutes xylazine @ 1 mg/kg body wt. and pentazocine @ 1 mg/kg body wt. were administered, intramuscularly one after the other, in separate syringes as preanesthetic. In subgroup D1 as preanesthetic, glycopyrrolate @ 0.005 mg/kg body wt. was administered, intramuscularly. After 15 minutes, diazepam @ 0.5 mg/kg body wt. and fentanyl citrate @ 10 µg/kg body wt. were administered intravenously one after the other, in separate syringes. In subgroup D2, glycopyrrolate @ 0.005 mg/kg body wt. was intramuscularly administered. After 15 minutes, diazepam @ 1 mg/kg body wt. and fentanyl citrate @ 5 µg/kg body wt. were administered, intravenously, one after the other, in separate syringes. After 15 minutes of preanesthetic administration in all groups anaesthesia was induced with propofol @ 2- 6 mg/kg IV “till effect”. After induction of anaesthesia the animals were intubated with endotracheal tube of suitable size and anaesthesia was maintained with isoflurane using small animal anaesthesia machine in semi closed circle system keeping the vaporizer setting between 1-3% depending on the requirement as evidenced by the status of different reflexes and pain response shown by the animal. The anaesthesia was maintained up to 60 min. or till completion of surgical procedure.

The jaw tone was abolished earlier in subgroup X1 in comparison to subgroups X2, D1 and D2. Abolition of pedal, palpebral, cornel reflexes happened earlier in D2 subgroup in comparison to X1, X2 and D1. Induction dose of propofol was lower in xylazine group than the diazepam group viz. 3.65 ± 0.60 mg/kg in subgroup X1, 4.00± 0.30 in subgroup X2 and 6.08±2.03 in subgroup D1, 4.53±0.48 in subgroup D2. Glycopyrrolate caused tachycardia in all subgroup. a₂-agonists did not cause bradycardia and diazepam did not alter heart rate and respiratory rate, whereas propofol caused tachycardia and depression in respiratory rate and SPO₂. Mean arterial pressure (MAP) increased after the administration of glycopyrrolate, xylazine and pentazocine in subgroup X1 while it slightly decreased in rest of the subgroups. The values of Hb, PCV did not changed significantly in all the subgroups. Blood glucose was increased after administration of drugs in any of subgroups. Blood urea nitrogen and creatinine values did not change significantly in any of the subgroups and remained in normal physiological limit. It was concluded from the study that Preanaesthetic combination of glycopyrrolate (0.005 mg/kg)-xylazine (0.5 mg/kg)-pentazocine (2 mg/kg) was found best among four combinations in terms of the quality of sedation, quality of induction, quality of recovery and dose sparing effect on induction and maintenance agents. Intramuscular anaesthetic protocol using glycopyrrolate (0.005 mg/kg)-xylazine (0.5 mg/kg)- pentazocine (2 mg/kg) (group X1) is recommended for the aggressive and uncooperative animals. Whereas, intravenous preanaesthetic protocol using glycopyrrolate (0.005 mg/kg)- diazepam (1 mg/kg)- fentanyl (5 µg/kg) is recommended for calm and cooperative animals. In terms of cardio respiratory, haemato-biochemical, and haemodynamic stability, the four preanaesthetic combinations were equivalent and did not cause any serious impacts on these parameters, hence they are approved for routine surgical procedures lasting about 60 minutes in dogs.