Perioperative anaesthetic complications in healthy cats undergoing anaesthesia for neutering in first opinion practice.

Objectives: The aim of the present study was to identify the incidence of common perioperative anaesthetic complications in cats undergoing anaesthesia for neutering in three UK first opinion practices.

Methods: A retrospective anaesthetic record analysis was performed on cats anaesthetised for neutering at practices 1 and 2 between 9 December 2017 and 2 February 2021 and practice 3 between 9 March 2020 and 7 January 2021. A search of the practice management system identified all cats that had undergone neutering in the selected timeframe. Data from 1019 cats were included in the study. Information relating to patient characteristics and data from the anaesthesia session were extracted from electronic patient records and anaesthesia record charts and entered into an Excel spreadsheet. A definition of the complications was created after reviewing the literature and their incidence determined from the data set. Comparisons between different groups of cats in the study were made using a χ² test for homogeneity or Fisher's exact tests to identify factors associated with increased incidence of complications.

Results: The anaesthetic-related mortality was 1/1019 (0.10%). The most common complications were hypotension (22.6%), bradycardia (16.7%) and hypothermia (13.8%). Less common complications were hypocapnia (12.7%), hypercapnia (8.7%), tachycardia (6.6%), apnoea (3.1%), hyperthermia (1.7%), hypertension (1.4%), endotracheal tube obstruction (1.1%), hypoxia (0.3%), undesirable recovery (0.6%) and cardiac arrhythmia (0.2%). Factors associated with increased risk of hypotension were acepromazine pre-anaesthetic medication, higher maximum isoflurane dose, longer anaesthetic duration and lower body weight. Factors associated with increased risk of bradycardia were medetomidine pre-anaesthetic medication, longer anaesthetic duration and higher body weight. Factors associated with increased risk of hypothermia were higher maximum isoflurane dose, increased anaesthetic duration and lower body weight.

Conclusions and relevance: This study showed that anaesthetic complications were frequently observed, with complications documented in 53.4% of the cats in the study. The information in this study may help to guide prioritisation of monitoring in feline anaesthesia.