Mastitis is an inflammatory disease of the bovine mammary gland caused by bacterial, viral, fungal, or parasitic infections, with pathogens primarily entering through the teat canal. Once established, they proliferate and evade host immunity, triggering complex immunological cascades mediated by bacterial toxins, proteins, and immunomodulators, which can result in increased somatic cell counts, vascular permeability, fibrosis, and systemic toxemia in severe cases. Mycotic mastitis is mainly caused by yeasts, although filamentous fungi, particularly Aspergillus fumigatus, have been reported, while viral infections may contribute indirectly through immunosuppression. Clinically, mastitis presents as swelling and tenderness of the udder, fever, and depression, and may occur as clinical or subclinical disease, classified by duration as acute or chronic. Early diagnosis relies on tests such as the California Mastitis Test and somatic cell count, while disease severity is influenced by host, pathogen, and environmental interactions. Histopathologically, mastitis can manifest in multiple forms: lymphoplasmacytic mastitis with chronic interstitial lymphocyte, plasma cell, and macrophage infiltration; pyogranulomatous lesions with necrosis, neutrophils, epithelioid macrophages, and peripheral fibrosis; suppurative and abscedative lesions showing squamous metaplasia and hemorrhages; necrosuppurative mastitis with multifocal coagulation necrosis; granulomatous lesions with necrotic, sometimes mineralized foci; and mixed-type lesions displaying overlapping features. Early detection, appropriate therapeutic intervention, and good management practices are critical to reduce the prevalence and severity of bovine mastitis.

California mastitis test, Bovine, Mastitis, Mycotic and viral infections, Pathological lesions