Figure 14

A schematic presentation of a two-phase proposal for the development of Escherichia coli mastitis. Phase 1 - The acute phase: Bacterial infection in the mammary gland or lipopolysaccharide (LPS) induced mastitis, trigger an immediate immune and inflammatory responses in which the endothelial-mammary barriers are open, allowing for cellular and humoral infiltration from blood to milk. Phase 2 - The chronic phase: The tight junctions close and infiltration is limited to areas of deep damage in the gland, which may perpetuate alterations that are measured in milk regardless of bacterial clearance off the mammary gland.