Breed-Specific Anaesthetic Mortality in Dogs: Evidence from an Analysis of 55,019 Cases

Anaesthesia in dogs carries measurable risk, and whether this varies by breed is uncertain. We analysed a prospective, multicentre cohort of 55,019 canine anaesthetic procedures from premedication to 48 h post-extubation; after excluding euthanasias and non-anaesthetic deaths, 54,542 anaesthetics remained. Mixed-breed dogs served as the benchmark. Unadjusted mortality by breed, Fédération Cynologique Internationale (FCI) groups and sections used Wilson 95% CIs and χ²/Fisher tests; robust Poisson models adjusted for ASA status. Overall mortality was 0.69% (378/54,542; 95% CI 0.62-0.76), with mixed-breed dogs at 0.68% (109/16,129). Unadjusted rates were higher for German Shepherd Dog (1.46%), Chihuahua (1.35%) and Bulldog (1.26%); no FCI group differed, while the Chihuahueno section was higher. Brachycephalic dogs showed higher crude mortality than non-brachycephalics (0.82% vs. 0.65%), but this attenuated with ASA adjustment (RR 1.19, 95% CI 0.96-1.47). MDR1-associated breeds did not differ in crude or adjusted analyses (adjusted RR, 1.14; 95% CI, 0.61-2.14). After ASA adjustment, excess risk persisted for Chihuahua (RR 1.80, 95% CI 1.08-2.99) and Spanish Water Dog (RR 2.72, 95% CI 1.23-6.01), but not for German Shepherd Dog or Bulldog. Anaesthetic mortality was low overall; between-breed differences largely reflected case severity, supporting breed-aware, ASA-centred risk communication and further breed-specific research.