FMD is highly contagious. It can spread over great distances through direct contact between infected and susceptible animals, and through indirect contact with contaminated animal products (meat, raw milk, hides), feed, bedding, and inanimate objects (fomites). Large amounts of virus will be present in tissues, excretions, and secretions (including milk, blood, semen, urine and faeces) shortly before the onset of clinical signs in cattle and pigs, and one or two days before the appearance of clinical signs in sheep. Mechanical transfer of infected meat or bones by dogs, foxes or birds is possible. In Canada's 1952 outbreak, a second nidus of infection in April was attributed to contaminated meat bones that were held in a freezer but later carried off by dogs.
https://web.archive.org/web/20080605152948/http://www.inspection.gc.ca/english/anima/heasan/disemala/fmdfie/plan/plan-1e.shtml