Cardiopulmonary Effects of Xylazine, Ketamine and Propofol Infusions in Anesthetized Llamas

Principal investigator:

Tanya Duke, BVetMed, MSci, DACVAA
University of Saskatchewan

There are no reports describing suitable injectable anesthesia techniques in camelids. We designed a suitable injectable anesthesia drug regimen and compared the quality of anesthesia and cardiopulmonary stability to results from using conventional isoflurane inhalational anesthesia.

Institution ethics approval was obtained (20170090). Five university-owned alpacas were anesthetized using xylazine and ketamine, the trachea was intubated, and anesthesia was maintained with either isoflurane delivered using an anesthetic machine, or with injectable infusions of anesthetic drugs (xylazine, propofol, ketamine) for 2 hours. Alpacas were allowed to spontaneously breathe an inspired concentration of 33% oxygen. The following variables were measured: systemic arterial blood pressure; heart and respiratory rates; lung tidal volume and minute ventilation; cardiac output ; end-tidal carbon dioxide and isoflurane (where appropriate) and arterial blood samples were withdrawn at pre-determined time-points. Extra drugs required were recorded. Blood samples were analyzed for pH, oxygen and carbon dioxide partial pressure; glucose, electrolytes, lactate and hemoglobin concentrations. Recovery times were recorded, and quality of recovery from anesthesia was scored.

Both anesthetic regimens provided good cardiopulmonary stability in these alpacas with no complications. The injectable anesthetic technique maintained higher blood pressure compared to the isoflurane group and all alpacas were well oxygenated. One alpaca recovering from isoflurane had a dysphoric recovery and produced a high lactate concentration from high muscle activity. Recovery from the injectable anesthesia was smooth with no signs of prolonged recovery from drug accumulation. Most alpacas were standing by 40 minutes following injectable anesthesia and by 60 minutes following isoflurane anesthesia.

We found the following infusion rates for injectable drugs were suitable to maintain anesthesia for 2 hours and could be used in situations where inhalational anesthesia is not available.