Small animal Review

Hypothermia during anaesthesia has a number of negative consequences, including increased risk of surgical site infection, bradycardia, hypotension, arrhythmia, reduced respiratory rate and poor response to drugs used to correct hypotension and bradycardia.

Cats have a relatively large body surface area to weight ratio and many cats presenting for neutering have relatively little body fat and are therefore at increased risk of hypothermia. Evaporation of isopropyl alcohol will cause significant cooling – but is this clinically relevant?

Kreisler et al (2021) comparted body temperatures in 157 cats undergoing spaying at a trap-neuter-return clinic. Cats were randomly assigned to receive chlorhexidine or isopropyl alcohol rinse for surgical site preparation. Anaesthesia was induced with intramuscular triple combination. Median body weight was 2.7kg and median estimated age was 12 months. Median temperatures on completion were 37.2°C for the chlorhexidine cats (a fall of 1.5 °C) and 37.4 °C for isopropyl alcohol cats (1.3 °C fall), which was not statistically significantly different. Small body size and poor body condition were associated with greater falls in temperature. There was no difference between a flank vs. midline approach. For the first 30 minutes, the average fall is temperature was 0.03 °C/min; after 30 minutes the fall was 0.01 °C/min.