Histopathological findings in the mammary gland of cattle diagnosed with clinical mastitis in the slaughter plant of the municipality of Ipiales (Colombia)

Abstract

Mastitis is the inflammation of the mammary gland and symptoms can range from increased somatic cell count without macroscopic changes in milk to progressive fibrosis or severe toxemia. In order to describe histopathological findings in the mammary gland of dairy cows diagnosed with clinical mastitis by the California Mastitis Test (CMT), a descriptive study was conducted in the slaughter plant of the municipality of Ipiales (Nariño, Colombia). CMT was performed during ante-mortem inspection post slaughter, breast tissue and nipple skin samples were collected from 332 bovine quarters. Samples were fixed in 10% buffered formalin and processed by inclusion in paraffin and hematoxylin and eosin staining. CMT evidenced grade 1 mastitis (46.2%), grade 2 (26.9%), and grade 3 (26.9%) in anterior quarters. In posterior quarters, grade 1 (44.24%), grade 2 (19.23%), and grade 3 mastitis (36.53%) were found. Histopathological study evidenced mastitis with intraductal and periductal distribution (70.19%) with mixed inflammatory infiltrate (41.34%). In 82.70% of the cases perivascular lymphocytic dermatitis was found. 30.76% of the cases were severe and 79.80% represented chronic cases.