Inflamed mammary tissue of three cows infected with Streptococcus uberis was found to have higher concentrations of 1α-hydroxylase than un-inflamed control mammary glands. Increased levels of 1α−hydroxylase resulted in increased production of 1,25-dihydroxyvitamin D3. Therefore, vitamin D3 may have a role in the inflammation and resolution of bovine mastitis.