Agreement of Hematologic Measurements Between Jugular and Coccygeal Puncture Sites in Cattle.

BACKGROUND: In bovine medicine, venipuncture is commonly performed at either the jugular or coccygeal vein. Although the coccygeal site is often preferred for practical reasons, sampling sites are inconsistently standardized in scientific studies. It is therefore important to determine whether hematologic values obtained from these two sites can be considered interchangeable. OBJECTIVES: To evaluate the statistical and clinical concordance of hematologic measurands obtained from paired jugular and coccygeal blood samples in cattle. METHODS: Paired jugular and coccygeal blood samples were collected from 48 adult cows and analyzed using an automated hematology analyzer, micro-hematocrit determination, and blood smear evaluation. Agreement between sites was assessed using Pearson and Lin's correlation coefficients, Passing-Bablok regression, and Bland-Altman analysis, with clinical relevance evaluated against published total allowable error (TEa) thresholds. RESULTS: Most hematologic measurands showed good agreement between jugular and coccygeal sampling sites. However, platelet counts, packed cell volume (PCV), and certain manual leukocyte differential counts on blood smears, particularly neutrophils and lymphocytes, demonstrated poorer agreement and should not be considered interchangeable. CONCLUSIONS: Jugular and coccygeal puncture sites yield largely comparable hematologic results for most automated measurands. However, platelet indices, packed cell volume, and manual leukocyte differentials on blood smears, particularly neutrophils and lymphocytes, show greater variability between sites and should not be considered interchangeable. In clinical settings, when results are compared with reference intervals or used for longitudinal monitoring, consistent use and documentation of the puncture site are recommended, and reference intervals established using the same sampling site should be applied for these variables.