Retrospective Evaluation of Hematological Ratios in Dogs With Nonassociative Immune-Mediated Hemolytic Anemia: 206 Cases.

Abstract

BACKGROUND: The utility of hematological ratios in immune-mediated hemolytic anemia (IMHA) in dogs has seldom been investigated. HYPOTHESIS: Hematological ratios are associated with disease severity and outcome in dogs with IMHA. ANIMALS: Two hundred and six client-owned dogs with non-associative IMHA. METHODS: Retrospective multicenter study. Medical records were reviewed to identify dogs with non-associative IMHA. The neutrophil-to-lymphocyte (NLR), neutrophil-to-monocyte (NMR), band neutrophil-to-segmented neutrophil (BNR), platelet-to-lymphocyte (PLR), monocyte-to-lymphocyte (MLR), neutrophil-to-platelet (NPR) and red blood cell distribution width-to-platelet (RDWPR) ratios were retrospectively calculated. Their association with hematological variables, number of blood transfusions, and survival at discharge, 1&#x2009;month, and 6&#x2009;months was evaluated. RESULTS: Of the 206 dogs included, 164 (80%, 95% confidence interval [CI]: 74-85), 144 (70%, 95% CI: 64-76), and 114 (55%; 95% CI: 48-62) were alive at discharge, one&#x2009;month, and six&#x2009;months, respectively. The hematological ratios were not associated with survival at any time point, regardless of treatment before referral. Only the RDWPR was associated with blood product requirement (odds ratio [OR], 0.70; 95% CI: 0.54-0.91; p&#x2009;<&#x2009;0.01). Dogs that had received glucocorticoids before referral had a higher 1-month mortality rate compared with glucocorticoid-na&#xef;ve dogs (73% and 67%, respectively; OR, 2.2; 95% CI: 1.1-4.5; p&#x2009;=&#x2009;0.03). CONCLUSIONS AND CLINICAL IMPORTANCE: Hematological ratios had limited value in predicting outcome or disease severity in a large population of dogs with non-associative IMHA. Glucocorticoid treatment before referral was independently associated with decreased survival, likely reflecting selection bias toward dogs with more severe disease.