Retrospective Evaluation of the Prognostic Value of Neutrophil‐to‐lymphocyte Ratio, Platelet‐to‐lymphocyte Ratio, and Mean Platelet Volume in Dogs Entering the ICU (2020–2022): 190 Cases

Objective To assess the prognostic relevance of the neutrophil‐to‐lymphocyte ratio (NLR), platelet‐to‐lymphocyte ratio (PLR), and mean platelet volume (MPV) in critically ill dogs at the time of ICU admission. Design Retrospective, observational, descriptive study. Setting Private referral center. Animals 200 dogs were enrolled in the study, 190 of which completed the study. Measurements and Main Results Signalment, diagnosis, affected body system, pathologic mechanism, concurrent disease, medications, hematology results, duration of hospitalization, and survival time were derived from the clinical notes of all dogs admitted to the ICU of a small animal referral hospital between January 2020 and March 2022. Kaplan–Meier plots were used to visualize associations between the NLR, PLR, MPV, and survival time, and between the NLR, PLR, MPV, and time to discharge. Cox proportional hazard models were used to investigate associations between the NLR, PLR, and MPV and both survival and time to discharge, while adjusting for covariates. Shorter survival times were identified in dogs with higher‐than‐bnormal NLR values ( p < 0.001), and markedly increased NLR values (> 15) were associated with longer hospitalization times ( p = 0.037). Dogs with abnormal PLR values were more likely to die or be euthanized than dogs with normal values ( p = 0.014). Conclusions An association between the NLR at the point of ICU admission and mortality and length of hospitalization suggests its potential use as prognostic biomarker.