A rapid and convenient method for detecting inflammatory conditions in breast tissue, such as those associated with mastitis, is described. The method comprises measuring the presence and quantity of Serum Amyloid A (SAA) in milk samples obtained from the breast tissue. The amount of SAA present in the milk is positively correlated with the level of inflammation of the breast tissue, and can localize the inflammation to a particular region of the breast organ, such as a specific quadrant of a cow's udder. Test kits and their use in the method are also described.