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

## TL;DR

This study finds that Persian and other flat-faced cat breeds have a higher risk of dying from anesthesia, even after accounting for their health status before the procedure.

## Contribution

The study provides evidence that brachycephalic cat breeds face higher anesthetic mortality risks, independent of pre-anaesthesia health.

## Key findings

- Anaesthetic-related mortality in cats was 0.63%, with higher rates in severely unwell cats.
- Persian cats had a 2.22 times higher risk of mortality compared to common breeds after adjusting for health.
- Brachycephalic breeds like Persian, Exotic Shorthair, and Himalayan showed a 2.33 times higher risk.

## Abstract

When cats undergo general anaesthesia for surgery or diagnostic procedures, a small number die during the anaesthetic period or shortly afterwards. Owners and veterinarians often ask whether a cat’s breed, and especially a “flat-faced” head shape, increases this risk. This study analysed anaesthetic records from multiple veterinary centres to estimate the frequency of anaesthetic-related deaths in cats and to compare risk across breeds, while also considering the cats’ pre-anaesthesia illness. Overall, 94 of 14,964 cats died during anaesthesia or within 48 h afterwards, which is about six deaths per 1000 anaesthetics. Deaths were far more frequent in cats that were already severely unwell before anaesthesia. For most breeds, the risk was similar to that of the common European or Domestic Shorthair cat. However, Persian cats remained at a higher risk even after adjusting for pre-anaesthetic health status. “Flat-faced” breeds such as Persian, Exotic Shorthair and Himalayan also showed a higher risk than non-flat-faced cats. These findings are valuable because they help veterinarians communicate risk more clearly to owners, improve planning and monitoring for higher-risk cats, and guide future work on safer anaesthesia for flat-faced breeds.

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).