PhD

The present study was undertaken to findout the efficacy of tiletamine – zolazepam alone and with xylazine premedication for anaesthesia in dogs and to evaluate the systemic changes consequent on the administration of these drugs. The experimental study was conducted on 36 adult non- descript dogs of either sex. The animals were randomly divided into two groups, (Group I and II ) consisting of 18 animals each. Each group was further divided into three subgroups, viz A, B and C, consisting of six animals each.

Atopine sulphate (0.04 mg/kg bodyweight) was administered IM 15 minutes prior to the administration of the experimental drugs in all the dogs. Tiletamine – zolazepam (T-Z) combination was administered IM at the rate of 5mg, 10 mg and 15 mg/kg bodyweight in the subgroups IA, IB and IC respectively. Xylazine at the rate of 0.5 mg/kg bodyweight and 15 later, T-Z combination at the rate of 5 mg, 10 mg and 15mg/kg bodyweight were administered IM in the subgroups IIA , IIB and IIC respectively.

The induction time was 6.17 + 1.01 min, 4.33 + 0.21 min and 4.33 + 0.49 min in subgroups IA, IB and IC respectively, and 3.33 + 0.62 min, 3.17 + 0.48 min and 2.83 + 0.54 min in subgroups IIA, IIB and IIC respectively. Increase in the dose of T-Z reduced the induction time and premedication with xylazine further reduced the induction time and induction was smooth.

The onset of effect of tiletamine – zolazepm was characterized by the winking of eyes, yawning, licking and protrusion of tongue. The eyes remained open and pupils were slightly dilated. The palpebral and pedal reflexes and swallowing movements were not abolished. Salivation was scanty in both the groups.

In the animals of group II the eyes were partially closed and palpebral and pedal reflexes were abolished but the swallowing movements were not. Protrusion of tongue, though present, was not to the extent that was observed in the animals of group I. Rhythmic side to side head movements were noticed during induction in all the animals of group I but not in animals of Group II.

The duration of anaesthesia was 33.67 +5.88 min, 57.83 + 6.17 min, and 89.00 +2.86 min in subgroups IA, IB and IC respectively, whereas it was for 49.67 + 6.643 min, 105.17 + 10.31 min AND 125.83 + 10.78 min in subgroups IIA, IIB and IIC respectively. An increase in the dose of tiletamine – zolazepam had prolonged the duration of anaesthesia and premedication with xylazine produced still longer duration of anaesthesia.

The jaw musculature maintained the tonus with the lower doses of tiletamine – zolazepm, but at 15 mg/kg bodyweight, the jaw muscles, though not fully relaxed, permitted endotracheal intubation. Administration of tiletamine – zolazepam with xylazine resulted in relaxation of the jaw muscles and permitted endotracheal intubation. Relaxation of the abdominal muscles was moderate to good when tiletamine – zolazepam alone was administered, whereas it was excellent with xylazine premedication.

Administration of tiletamine – zolazepam alone was found insufficient for carrying out surgical procedures, but with xylazine premedication muscle relaxation and analgesia was satisfactory.

The recovery time was 111.50 + 14.53 min, 116.50 + 10.46 min and 180.33 + 10.57 min in subgroups IA,IB and IC respectively, and it was 160.00 + 17.70 min, 180.00 + 14.94 min and 181.06 + 12.82 min in subgroups IIA, IIB and IIC respectively. Increase in the dose of tiletamine – zolazepam had delayed recovery and xylazine premedication delayed it still further. During recovery, paddling and vocalization were common in dogs of group I but not in dogs of group II.

Reduction in rectal temperature was observed only in animals of subgroups IB and IC and in all the animals of Group II. Marked increase in pulse rate was observed in group I than in Group II. Respiration rate was decreased in both the groups.

A mild increase in diastolic pressure was observed in Group I. The systolic and diastolic pressure were seen decreased in Group II. The changes in the coagulation time of blood was within the normal limits in both the groups.

Increase in heart rate with depression of T-wave, biphasic T-wave and spiking of T-wave were the changes in electrocardiogram. But the changes were corrected spontaneously.

There was slight decrease in the erythrocyte sedimentation rate in animals of group I but there was no change in Group II.

Reduction in the packed cell volume was observed in both the groups, but it was more, after xylazine premedication.

Slight decrease in haemoglobin concentration was noticed in subgroup IC. But there was no change in Group II.

Decrease in total erythrocyte count was noticed in both the group and the decrease was more when premedicated with xylazine.

The total leukocyte count was seen increased in subgroup IA and IB but it was seen decreased in subgroup IC, but there was no change in group II.

Decrease in lymphocyte count with increase in neutrophil count was observed in subgroups IA and IIA. In subgroups IB and IC there were increase in lymphocyte count with decrease in neutrophil count, but in subgroups IIB and IIC a decrease or no alteration in the count of lymphocytes was observed. Monocyte and eosinophil counts were increased and the basophil count remained insignificant.

There was marked increase in the serum glucose value following the the administration of tiletamine – zolazepam and with xylazine premedication the increase was more.

No significant change was observed in the serum electrolytes (Na+, K+, and Cl-), total serum protein content and serum urea nitrogen value in both the groups.

Slight increase in serum aspartate aminotransferase (AST) and serum alanine aminotransferase (ALT) values were observed in Group I,and in Group II there was increase in AST value, but the ALT value decreased initially and was followed by an increase.

Histopathological examination of liver revealed cloudy swelling and mild fatty changes and kidney revealed cystic dilation of the renal tubules along with focal areas of nephrosis.