To explore the major risk factors linking preoperative characteristics and anaesthesia-related
death in dogs in referral hospitals in Japan.
Observational cohort study.
From April 1, 2010 to March 31, 2011, 4323 dogs anaesthetized in 18 referral hospitals
Questionnaire forms were collated anonymously. Death occurring within 48 hours after
extubation was considered as an anaesthesia-related death. Patient outcome (alive
or dead) was set as the outcome variable. Preoperative general physical characteristics,
complete blood cell counts, serum biochemical examinations and intraoperative complications
were set as explanatory variables. The risk factors for anaesthesia-related death
were evaluated using chi-square test or Fisher's exact test, followed by multivariable
logistic regression analysis of the data. Significance was set at p < 0.05.
Thirteen dogs that died from surgical error or euthanasia were excluded from statistical
analysis. The total mortality rate in this study was 0.65% [28/4310 dogs; 95% confidence
interval (CI), 0.41–0.89]. Furthermore, 75% (95% CI, 55.1–89.3) of anaesthesia-related
deaths occurred in dogs with pre-existing diseases. Most of the deaths occurred postoperatively
(23/28; 82.1%; 95% CI, 63.1–93.9). Preoperative serum glucose concentration <77 mg dL–1 (6/46; 13.0%; 95% CI, 4.9–26.3), disturbance of consciousness (6/50; 12.0%; 95% CI,
4.5–24.3), white cell count >15,200 μL–1 (16/499; 3.4%; 95% CI, 1.9–5.5) and American Society of Anesthesiologists grade III–V
(19/1092; 1.7%; 95% CI, 1.1–2.7) were identified as risk factors for anaesthesia-related
death. Intraoperative hypoxaemia (8/34; 23.5%; 95% CI, 10.7–41.2) and tachycardia
(4/148; 2.7%; 95% CI, 0.7–6.8) were also risk factors for anaesthesia-related death.
Conclusions and clinical relevance
The results revealed that certain preoperative characteristics were associated with
increased odds of anaesthesia-related death, specifically low serum glucose concentration
and disturbances of consciousness. Greater attention to correcting preanaesthetic
patient abnormalities may reduce the risk of anaesthesia-related death.