The risk of death: the confidential enquiry into perioperative small animal fatalities.

OBJECTIVE To estimate the risks of anaesthetic and sedation-related mortality in companion animals in the UK. (The Confidential Enquiry into Perioperative Small Animal Fatalities, CEPSAF). STUDY DESIGN A prospective cohort study with nested case-control study. ANIMAL POPULATION All small animals anaesthetized and sedated at participating centres between June 2002 and June 2004. METHODS Patient outcomes at 48 hours (alive, dead and killed) were recorded. Anaesthetic and sedation-related death was defined as death where surgical or pre-existing medical causes did not solely cause death. Species-specific risks of anaesthetic-related death and 95% confidence intervals (95% CI) were calculated. Risks were also estimated in the sub-sets of dogs, cats and rabbits that were either healthy or sick (ASA 1-2 and 3-5, respectively). RESULTS One hundred and seventeen veterinary practices participated in the study and 98 036 dogs, 79 178 cats and 8209 rabbits were anaesthetized and sedated. Overall risks of anaesthetic and sedation-related death in dogs were 0.17% (1 in 601, 95% CI 0.14-0.19%), in cats 0.24% (1 in 419, 95% CI 0.20-0.27%) and in rabbits 1.39% (1 in 72, 95% CI 1.14-1.64%) within 48 hours of the procedure. In healthy dogs, cats and rabbits, the risks were estimated to be 0.05% (1 in 1849, 95% CI 0.04-0.07%), 0.11%, (1 in 895, 95% CI 0.09-0.14%) and 0.73% (1 in 137, 95% CI 0.54-0.93%), respectively. In sick dogs, cats and rabbits, the risks were 1.33%, (1 in 75, 95% CI 1.07-1.60%), 1.40% (1 in 71, 95% CI 1.12-1.68%) and 7.37% (1 in 14, 95% CI 5.20-9.54%), respectively. Postoperative deaths accounted for 47% of deaths in dogs, 61% in cats and 64% in rabbits. Most other small animal species had higher mortality risks. CONCLUSIONS AND CLINICAL RELEVANCE Small animal anaesthesia appears to be increasingly safe. Greater patient care in the postoperative period could reduce fatalities.