Clinically inapparent infections can occur, particularly in cattle and sheep. Such animals excrete virus and contribute to the spread of the disease. Post infection carrier states occur in cattle, sheep and goats in a high proportion of animals and can persist for up to 3 years or more in cattle, with lesser periods in sheep and goats. After an incubation period of 2 to 8 days, fever, depression and anorexia are noted with formation of vesicles in and around the mouth and in the bulbs of the heels, interdigital cleft and coronary bands of the feet. Vesicles may also be observed on the teats of lactating animals.
Attack rates are very high, though mortality is low.
Most deaths are in calves as a result of myocarditis. However production losses are high including permanent reductions in milk production and reproductive performance. Chronic illness, of uncertain pathogenesis often results also. The clinical signs of FMD and vesicular stomatitis are identical in ruminants and pigs. It is therefore essential that any occurrence of vesicular disease in ruminants or pigs be regarded seriously and no attempt made to differentiate them on clinical grounds.