Retrospective evaluation of hematological ratios in canine parvovirosis: 401 cases

Abstract Background The utility of neutrophil‐to‐lymphocyte ratio (NLR), platelet to‐lymphocyte ratio (PLR) and monocyte‐to‐lymphocyte ratio (MLR) as prognostic indicators has not been investigated in canine parvovirosis (CPV). Hypothesis To evaluate whether these hematological ratios obtained at hospital admission in CPV are associated with outcome or duration of hospitalization. Animals. Four hundred one client‐owned dogs presented with CPV. Methods‐Retrospective multicenter cohort study. Medical records were reviewed to identify dogs with CPV. Data regarding signalment, complete blood count at admission, duration of hospitalization and outcome were collected. Results Of the 401 dogs included in the study, 336 (83.8%) survived to discharge. The median (25th and 75th percentiles) PLR in nonsurvivors (336.56 [159.84‐635.77]) was significantly higher than in survivors (217.65 [117.67‐389.65]) (P = .003). The area under the receiver‐operating characteristic curve for nonsurvival was 0.615 (95% CI [0.593‐0.691], P = .003). A cut off of 700 showed a 21.5% sensitivity and 90% specificity for nonsurvival. No association was observed between hospitalization duration and either hematological ratios or total WBC counts. The median (25th and 75th percentiles) lymphocyte count was below reference interval in all dogs and was significantly lower in the dogs which died (0.82 × 109/L [0.5‐1.87]) than in survivors (1.27 × 109/L [0.73‐2.22]) (P = .005). The median (25th and 75th percentiles) monocyte count however was lower in survivors (0.38 × 109/L [0.29‐1.59]), than in nonsurvivors (0.73 × 109/L [0.1‐2]) (P = .002). Conclusions Evaluation of PLR at hospital admission might be a useful marker of disease severity and could have prognostic value in dogs with CPV.