Twenty-five multiparous Holstein cows were grouped according to infection status with Mycobacterium avium subsp. paratuberculosis (MAP), the causative microorganism of Johne’s disease (JD). Osteopontin (Opn) was characterized at both the level of gene and protein expression. Results of this study indicate that in dairy cows, expression of Opn is modulated by natural infection with MAP and by the periparturient period.