Complete blood count interpretation in dogs and cats and its analytical compatibility with Vis-NIR point-of-care hematology: A systematic literature review with narrative synthesis

This systematic literature review with narrative synthesis assessed the diagnostic contribution of complete blood count (CBC) interpretation in dogs and cats combined only with anamnesis and physical examination, without biochemistry or imaging, and the compatibility of the CBC variables and CBC-derived indices identified with emerging point-of-care (POC) hematology platforms using visible-short-wave-near-infrared (Vis-NIR) spectroscopy and self-learning artificial intelligence (SLAI). Following PRISMA 2020 guidelines, studies published from 2015 to January 2026 were identified and integrated into tables associating hematological patterns, CBC-derived indices, clinical presentation, and differential diagnoses. The technology component was appraised separately for analytical compatibility, not as an independent systematic review. Recurrent signatures included inflammatory leukograms, regenerative and non-regenerative anemia, stress leukograms, leukopenic syndromes, and thrombocytopenic disorders. Conventional CBC findings and CBC-derived indices (neutrophil-to-lymphocyte, monocyte-to-lymphocyte, platelet-to-neutrophil and platelet-to-lymphocyte ratios, and the systemic immune-inflammation index) were investigated across infectious, inflammatory, neoplastic, endocrine, cardiovascular, and immune-mediated diseases. However, this evidence is concentrated on pyometra, parvovirosis, pancreatitis, parasitism, cardiopathies and endocrinopathies, derives predominantly from small studies in dogs; these indices remain non-specific markers of systemic inflammatory burden. For POC technology, proof-of-concept studies report agreement with reference analyzers for erythrocyte parameters and total leukocyte counts, but not for the differential and platelet counts several of these indices require. Analytical compatibility is therefore supported for selected CBC parameters, but not clinical validity for CBC-derived indices or disease diagnosis. Whether these platforms can enable rapid, minimally invasive, decentralized CBC monitoring, particularly in fragile, pediatric, geriatric, chronic, and palliative-care patients, remains to be demonstrated in clinical studies.