A review of perioperative mortality in pet rabbits in Australia.

Abstract

Introduction: Domestic rabbits have higher perioperative mortality rates (1.39%-4.8%) compared with dogs and cats (0.1%-0.2%), with cardiovascular and respiratory complications reported most. Understanding anaesthetic risk factors is essential to minimise mortality risks.

Objective: To determine the perioperative mortality risks and risk factors in rabbits undergoing general anaesthesia.

Methods: This retrospective cohort study evaluated 1757 records of rabbits that underwent general anaesthesia with inhaled isoflurane, categorised by the American Society of Anesthesiologists (ASA) physical status classification system (January 2019-April 2023). Data were collected on physical characteristics, anaesthetic protocol, airway management and patient outcomes. Potential risk factors were analysed using multivariable logistic regression modelling guided by directed acyclic graphs.

Results: The perioperative mortality risk was 2.05% (95% CI: 1.39, 2.71). Increased mortality was most associated with poorer health status (ASA score) and non-routine procedures. Following induction of anaesthesia, rabbits with a body mass of less than 1 kg (RR: 7.57, 95% CI: 1.18, 61.2) and Netherland Dwarf rabbits (RR: 23.4, 95% CI: 2.75, 200) were at higher risk. The use of a supraglottic airway device was protective against mortality during anaesthesia compared with endotracheal tubes (RR: 0.27, 95% CI 0, 3.78) and anaesthetic masks (RR: 0.42, 95% CI: 0, 3.71). Increased mortality was observed with a fentanyl-based protocol compared with a medetomidine-based protocol (RR: 4.62, 95% CI: 0.477, 44.7).

Discussion: Perioperative mortality was multifactorial, with health status, surgical complexity and physical characteristics representing primary risk factors. Clinicians should choose a suitable anaesthetic protocol, implement effective airway control and follow precautions for brachycephalic rabbit breeds.