Higher shock index at presentation is associated with mortality in stray cats at an emergency medical center

Background Rescued stray cats may present with disease or traumatic injury, but early risk assessment is challenging because background information, vaccination history, and the duration of illness or injury are often unavailable. Evidence remains limited regarding presentation-based indicators that can support immediate clinical assessment in stray cats requiring emergency medical care. This study evaluated whether shock index (SI), calculated as the ratio of heart rate to systolic blood pressure, was associated with mortality in stray cats that were presented to a veterinary emergency medical center. Methods The medical records of 63 stray cats that were presented to the Emergency Medical Center of Seoul National University Veterinary Medical Teaching Hospital between March 2021 and November 2024 were retrospectively reviewed. After excluding three cats with missing outcome data, 60 cats were included in the final study population. Demographic characteristics and clinical variables recorded at presentation were summarized and compared between survivors and non-survivors. Univariable and multivariable logistic regression analyses ( n = 47 complete cases) were performed to evaluate the association between SI at presentation and mortality at emergency department discharge, and model discrimination was assessed using receiver operating characteristic curve analysis. Results Of the 60 stray cats included in the final study population, 32 (53.3%) survived to discharge. In the multivariable analysis, SI at presentation was associated with higher mortality odds at emergency department discharge (odds ratio 3.23, 95% confidence interval [CI] [1.31–7.96], p = 0.011). The final model showed acceptable discrimination (area under the curve 0.788, 95% CI [0.658–0.918]). Conclusions SI at presentation was associated with mortality in this cohort of stray cats. SI assessment may support initial clinical evaluation in resource-limited settings, but prospective studies with external validation are needed.