Peri-anaesthetic complications in dogs undergoing lateral thoracotomy or median sternotomy: A retrospective study

To investigate the incidence of peri-anaesthetic complications in dogs undergoing general anaesthesia for thoracic surgery (lateral thoracotomy or median sternotomy) and to identify differences in the rate of peri-anaesthetic complications depending on the surgical approach and American Society of Anesthesiologists (ASA) physical status classification system.

Retrospective study.

Dogs that underwent either thoracotomy or sternotomy at The Small Animal Hospital, University of Edinburgh, between January 2019 and August 2022.

Data recorded included signalment, surgical approach, indication for surgery, general anaesthesia time, surgery time, time to extubation, anaesthetic management and the use of locoregional anaesthetic techniques, neuromuscular blockers, anticholinergics and/or vasopressor and inotropic agents. The occurrence of peri-anaesthetic complications (yes/no) was analysed by surgical approach and ASA classification using chi-square analysis and logistic regression. Statistical significance was set at p < 0.05.

A total of 127 anaesthetic records were reviewed, of which 90 met the inclusion criteria; ASA scores were missing from nine leaving 81. Median sternotomy was associated with a significantly longer surgical (p = 0.03) and anaesthetic time (p < 0.01) as well as the time to extubation (p = 0.023). Hypothermia (n = 72) and hypotension (n = 54) were the most prevalent complications observed despite surgical approach or ASA status. Hypoxaemia was more likely to occur in dogs with ASA status IV (n = 10/29) than in dogs with ASA status II and III (n = 7/52) in chi-square analysis (p = 0.026) and binomial logistic regression (p = 0.046).

Hypothermia and hypotension were common peri-anaesthetic complications. Higher ASA status was associated with a higher likelihood of hypoxaemia, and no significant association was found between complications and surgical approach. Active warming from the premedication stage and ensuring prompt access to fluid therapy, vasopressors, inotropes and anticholinergics are recommended.