Clinical trial of xylazine with ketamine in equine anaesthesia.

This study investigates the effects of combining the drugs xylazine and ketamine for equine anesthesia in a variety of surgical procedures. The findings suggest this drug combination may offer advantages compared to other common anesthesia methods for horses.

Experimental Design

• The study involved 100 anesthesia administrations to 95 horses, whose weights ranged between 140 and 1270 kg, and ages from nine months to 19 years old.
• The horses underwent various surgical procedures and not all were premedicated. For the ones who were, acepromazine maleate was used.
• The anesthetic protocol used was the intravenous administration of xylazine first (1.1 mg/kg over 2 minutes), followed by a brief pause and then ketamine (2.2 mg/kg).
• For 30 procedures, no other anesthetics were given. In other cases, the anesthesia was extended using halothane-oxygen, or with intravenous agents.
• Recumbency, or the action of lying down, was observed about 1.5 to 2 minutes post ketamine injection, with limb movements gradually dying down in the succeeding 30 to 60 seconds.

Results of the Experiment

• In 26 cases where other agents were not used, satisfactory operating conditions occurred for an average of 20 minutes.
• In instances where full muscle relaxation was not achieved, surgery was still possible.
• Recovery from anesthesia began abruptly but calmly. The average time for horses to stand after induction of anesthesia was 33 minutes. A remarkable absence of ataxia, a lack of voluntary coordination of muscle movements, was also noticed post anesthesia.
• A similar recovery was observed in the 56 instances where halothane-oxygen was used, with horses standing an average of 28 minutes post disconnection from the anesthetic system.
• Heart block was observed during induction of anesthesia but other cardiovascular and respiratory parameters were well maintained.

Conclusions and Implications

• The combination of xylazine and ketamine as an anesthetic technique presents advantages over other anesthesia protocols used in equine medicine.
• It allowed for satisfactory operating conditions and a quick, quiet recovery with minimal ataxia observed.
• The results of the study could influence future anesthetic protocols in equine veterinary medicine, pointing towards the preferred use of the xylazine-ketamine combination.