In general, when FMD affects pigs the disease is hardest to control. Pigs infected with FMD are tremendous sources of virus production. Pigs are able to generate infective aerosols up to 3000 times greater in virus concentration than cattle. Pig farms can generate an infective cloud, which can predictably be blown 60 km and infect other farms. Animals become ill between 2-14 days after infection.
Infected animals are infectious to others for several days prior to the onset of clinical signs.
The highly infectious nature of this agent and the fact that all species shed virus for considerable lengths of time prior to the development of clinical signs results in two dangerous situations. Secondly if the response does not include effective pre-emptive slaughter, that is the killing of animals prior to the development of clinical disease, you are unlikely to be able to control the outbreak. Canada has had significant experience in controlling tuberculosis and brucellosis of cattle. Both of these diseases are poorly infective compared to FMD or hog cholera. Response to foreign animal disease is important to minimizing the risk to our production systems.