FMDV produces an acute, systemic vesicular disease, which requires a differential diagnosis from other vesicular diseases [89] . In natural infection, the main route of virus entry is the respiratory tract. The initial virus multiplication usually takes place in the pharynx epithelium, producing primary vesicles, or "aphthae" [90] . The vesicles produced by FMDV generally affect cells from the epithelial stratum espinosum. The clinical outcome of the disease may vary among the host species considered and the infecting virus strain. In cattle and pigs, fever and viraemia usually start within 24-48 hr after epithelium infection, leading to viral spread into different organs and tissues and the production of secondary vesicles preferentially in the mouth and feet. The acute phase of disease lasts about 1 week and declines gradually coinciding with the emergence of a strong humoral response [91] .The morbidity and mortality in FMD depends upon the breed and age of the animal where mortality in adult animals is very low (two per cent) in comparison to 20 per cent in young stock [92] . The calves show prominent signs of myocarditis, whereas piglets manifest gastroenteritis [93] . In sheep and goats, symptoms are frequently less severe and may make the detection of the disease difficult [94] .