In intensively reared pigs, the introduction of foot and mouth disease (FMD) results in severe clinical disease and vesicular lesions in adult and fattening animals, and high mortality in piglets. Vaccination of uninfected herds can assist FMD control and eradication programmes by reducing susceptibility of pigs older than 12 to 14 weeks and providing early protection to piglets through maternal antibody, but once FMD is established on a farm, vaccination alone will not prevent recurrent outbreaks of clinical disease.