Breed-Specific Anaesthetic Mortality in Cats: Evidence from an Analysis of 14,964 Cases.

Anaesthetic-related mortality in cats is uncommon, yet concerns persist regarding potential breed predispositions and the influence of brachycephalic conformation. This study evaluated breed-specific peri-anaesthetic death before and after adjustment for American Society of Anesthesiologists (ASA) physical status. It explored whether genomic lineage or brachycephalic phenotype was associated with mortality. A prospective, multicentre cohort of general anaesthetics from 198 centres was analysed. Anaesthetic-related death was defined as death during anaesthesia or within 48 h after extubation, excluding euthanasia and deaths attributed to non-anaesthetic causes. Breeds were grouped into four genomic lineages and three brachycephalic phenotypes. Mortality proportions (Wilson 95% confidence intervals) were calculated, and relative risks (RR) were estimated using Poisson regression with robust standard errors, adjusting for ASA class. Among 14,964 cats, 94 deaths occurred (0.63%; 95% CI 0.51-0.77), with mortality increasing from 0.07% (ASA I) to 33.33% (ASA V). After ASA adjustment, most breeds did not differ from European/Domestic Shorthair cats, but Persians remained at increased risk (RR 2.22; 95% CI 1.11-4.46). Mortality did not differ between genomic lineages. Moderate brachycephaly was not associated with an increased risk, whereas brachycephalic breeds (Persian, Exotic Shorthair, Himalayan) showed a higher adjusted risk (RR = 2.33; 95% CI, 1.17-4.63).