FMD should be suspected wherever vesicles are seen in cloven-hoofed animals. Vesicles begin as small white fluid filled areas that quickly grow to a blister about 3 cm in diameter. Two or more blisters may join to form a large one. The blisters usually burst leaving a raw surface. These heal over a few days. Other suggestive signs include:
- sudden lameness in a number of animals
- loss of appetite
- in dairy cattle, a sudden drop in milk yield
In cattle, the earliest signs are dullness, poor appetite, fever. Salivation and lameness may be seen. Vesicles appear inside the mouth on the tongue, cheeks and gums, lips and palate. Vesicles may form between the claws of the feet and along the coronary band. They may also appear on the teats and udder Þ Reduced lactation, mastitis and abortion are common. Mortality in adults is usually very low. However, up to 50% of calves may die due to cardiac involvement, secondary infections, exposure and malnutrition.
Photo gallery: Ageing of lesions
In pigs, the main sign is lameness. There is also fever and loss of appetite. Vesicles form along the top of the foot, on the heels and between the claws. The feet are sore and affected pigs prefer not to move. Vesicles may also be formed on the snout, but tend to rupture quickly. Abortion is common. Mortality in piglets can be high.
SHEEP and GOATS
In sheep and goats, the disease is usually milder with fewer lesions. Affected sheep are depressed and reluctant to stand. Some animals may develop sudden lameness. Vesicles form around the top of the foot and between the claws. Lesions may develop on the tongue and dental pad, but can be hard to detect. Significant mortality can occur in lambs.
In addition to the lesions described above, lesions may also be present in the rumen. In young animals there is focal necrosis of cardiac muscle.