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Reference Intervals for Hematological Inflammatory Ratios in Healthy Dogs
1
Facultad de Veterinaria y Ciencias Experimentales, Universidad Católica de Valencia San Vicente Mártir, 46001 Valencia, Spain
2
Escuela de Doctorado, Universidad Católica de Valencia San Vicente Mártir, 46001 Valencia, Spain
3
Hospital Veterinario UCV, Universidad Católica de Valencia San Vicente Mártir, 46018 Valencia, Spain
*
Author to whom correspondence should be addressed.
Animals 2025, 15(23), 3376; https://doi.org/10.3390/ani15233376
Submission received: 12 October 2025
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Revised: 18 November 2025
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Accepted: 19 November 2025
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Published: 21 November 2025
(This article belongs to the Section Companion Animals)
Simple Summary
In the present study, reference intervals for hematological ratios in dogs were established. Hematological inflammatory ratios, such as the neutrophil-to-lymphocyte (NLR), monocyte-to-lymphocyte (MLR), platelet-to-lymphocyte (PLR), and systemic inflammatory index (SII), are widely used because they are easily calculated from a complete blood count and involve no additional cost. Hematological ratios have recently demonstrated prognostic value in acute inflammatory diseases, neoplastic conditions, hepatic and gastrointestinal pathologies, as well as acting as biomarkers for the early detection of tumors and cardiorespiratory diseases. The following reference intervals were established: 1.3–7.1 for NLR; 0.1–0.3 for MLR; 40.4–271.1 for PLR, and 224.6–2191.7 for SII. This may represent a useful tool in clinical practice, enabling rapid comparison and supporting clinicians in prognostic assessment of certain diseases, as well as potentially serving as a predictive biomarker.
Abstract
Hematological inflammatory ratios such as the neutrophil-to-lymphocyte (NLR), monocyte-to-lymphocyte (MLR), platelet-to-lymphocyte (PLR), and systemic inflammatory index (SII) have recently demonstrated prognostic value in acute inflammatory diseases, neoplastic conditions, hepatic and gastrointestinal pathologies, as well as acting as biomarkers for the early detection of tumors and cardiorespiratory diseases. In addition, they can be easily calculated and have no additional cost. The purpose of this study was to establish reference ranges for these ratios in the canine population, thereby providing support for clinical practice. Data was collected from previous studies. The dogs included in the study had to have anamnesis and physical examination without abnormalities and within reference limits in laboratory results. A total of 156 samples were included and divided by sex and age. The following reference intervals were established: 1.3–7.1 for NLR; 0.1–0.3 for MLR; 40.4–271.1 for PLR, and 224.6–2191.7 for SII. Statistical significant difference was found between sexes and NLR, with males showing a higher ratio than females. Regarding age, statistical significance was found between juveniles and senior dogs for NLR. PLR and SII showed higher ratios in senior dogs compared to adults and juveniles. This study may serve as a guide in clinical practice for the interpretation of hematological inflammatory ratios.
Keywords:
canine; hematological inflammatory ratios; MLR; NLR; PLR; reference interval; SII
