Plain-English summary
"Will my pet wake up?" is one of the most common fears owners bring to a routine procedure, and it is usually answered with reassurance rather than numbers.
This study provides the numbers. Across 117 UK veterinary practices and more than 185,000 anaesthetics, the risk of anaesthetic-related death was about 1 in 601 for dogs and 1 in 419 for cats. For animals that were healthy going in, it fell to roughly 1 in 1,849 and 1 in 895.
The finding that changes anything practical, though, is about when. Around half of the deaths in dogs, and closer to two-thirds in cats and rabbits, happened after the procedure rather than during it.
What the study found
The Confidential Enquiry into Perioperative Small Animal Fatalities was a prospective cohort study with a nested case-control component, recording every animal anaesthetised or sedated at participating centres between June 2002 and June 2004. Outcomes were recorded at 48 hours. An anaesthetic-related death was defined as one where surgical or pre-existing medical causes did not solely account for it.
One hundred and seventeen practices took part. The study covered 98,036 dogs, 79,178 cats and 8,209 rabbits.
Overall risk of anaesthetic and sedation-related death within 48 hours was 0.17% in dogs (1 in 601, 95% CI 0.14–0.19%), 0.24% in cats (1 in 419, 95% CI 0.20–0.27%) and 1.39% in rabbits (1 in 72, 95% CI 1.14–1.64%).
Health status separated those figures sharply. In healthy animals — ASA grades 1 to 2 — the risks were 0.05% in dogs (1 in 1,849), 0.11% in cats (1 in 895) and 0.73% in rabbits (1 in 137). In sick animals, ASA 3 to 5, they were 1.33% in dogs (1 in 75), 1.40% in cats (1 in 71) and 7.37% in rabbits (1 in 14).
Postoperative deaths accounted for 47% of deaths in dogs, 61% in cats and 64% in rabbits. Most other small animal species carried higher mortality risks than dogs and cats.
The authors conclude that small animal anaesthesia appears to be increasingly safe, and that greater patient care in the postoperative period could reduce fatalities.
What this study cannot tell you
The data was collected between 2002 and 2004. Anaesthetic drugs, monitoring equipment and protocols have all moved since, and the authors themselves frame their findings against a trend of improving safety.
More recent work complicates rather than confirms the picture. Worldwide prospective studies reported anaesthesia-related mortality of 0.69% in dogs and 0.63% in cats — several times the CEPSAF figures. Those studies drew on self-selected centres across many countries and list non-randomised sampling, unquantified response rates and subjectivity in classifying cause of death among their own limitations. So the difference may reflect population and method as much as any real change. Anyone quoting a single number for "the risk of anaesthesia" is oversimplifying.
CEPSAF describes UK practice, and participating practices volunteered — centres willing to be audited may not represent all centres.
Attribution is also a judgement. Deciding that a death was anaesthetic-related rather than caused by the underlying disease or the surgery is not a mechanical determination, and different assessors could classify differently.
Finally, these are population figures. They do not estimate risk for your animal, which depends on its age, health status, the procedure, and the team performing it — none of which a percentage from a national study can supply.
What pet owners should track
The postoperative finding is the actionable one, and it points at the period you are responsible for:
- Ask for and write down your animal's ASA health status grade before the procedure, since it is the single strongest factor in this study
- Record the discharge instructions as given, including what is normal and what is not, and the number to call out of hours
- Note eating, drinking, urinating, and toileting in the days after, along with the times
- Watch breathing and alertness during the first 48 hours, the window this study measured
- Record every medication given at home, with dose and time
- Note any previous anaesthetic and how your animal responded, since that history is asked for every time
If your animal seems unusually flat, has laboured breathing, will not settle, or deteriorates after coming home, contact the practice immediately. This study's central message is that the recovery period carries real risk, and out-of-hours contact details are given for a reason.
What PAWai can help organize
Anaesthetic history is one of the questions asked before every procedure and one of the hardest to answer from memory — which drug, which year, any complications. PAWai holds that history along with the postoperative notes you take at home. PAWai does not assess anaesthetic risk, does not assign ASA grades, and cannot tell you whether a procedure is safe for your animal. Risk assessment is a clinical judgement made from examination and, often, bloodwork. What PAWai contributes is that the previous anaesthetic, and how your animal recovered from it, is on record for the next one.
Disclaimer
PAWai organizes information and educates pet owners. PAWai does not diagnose conditions or recommend treatment. Always consult a licensed veterinarian for medical decisions about your pet.
Citation
Brodbelt, D. C., Blissitt, K. J., Hammond, R. A., Neath, P. J., Young, L. E., Pfeiffer, D. U., & Wood, J. L. N. (2008). The risk of death: the Confidential Enquiry into Perioperative Small Animal Fatalities. Veterinary Anaesthesia and Analgesia, 35(5), 365–373. https://doi.org/10.1111/j.1467-2995.2008.00397.x
Redondo, J. I., Otero, P. E., Martínez-Taboada, F., Doménech, L., Hernández-Magaña, E. Z., & Viscasillas, J. (2023). Anaesthetic mortality in dogs: a worldwide analysis and risk assessment. Veterinary Record, 195. https://doi.org/10.1002/vetr.3604
Redondo, J. I., Martínez-Taboada, F., Viscasillas, J., Doménech, L., Marti-Scharfhausen, R., Hernández-Magaña, E. Z., et al. (2024). Anaesthetic mortality in cats: a worldwide analysis and risk assessment. Veterinary Record, 195. https://doi.org/10.1002/vetr.4147