Nature of the disease
Foot-and-mouth disease (FMD) is a highly contagious viral disease of cloven-hoofed animals. The disease is characterised by the formation of vesicles (fluid-filled blisters) and erosions in the mouth, nose, teats and feet. Although not very lethal in adult animals, it causes serious production losses and is a major constraint in international trade.
Classification
OIE List A disease
Susceptible species
Cloven-hoofed animals (ungulates) are susceptible to FMD. Of the domestic species, cattle, buffaloes, pigs, sheep, goats and deer are susceptible. Horses are not affected.
Where it occurs
The FMD situation has improved markedly in recent years particularly in Europe and some countries in south east Asia and South America. However, the disease remains endemic and at a high prevalence in many countries in Africa, the Middle East, Asia and South America.
North and Central America, Pacific nations and the Caribbean are basically free of the disease.
Clinical signs
FMD should be suspected wherever vesicles are seen in cloven-hoofed animals. Vesicles begin as mall 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;
- salivation;
- fever;
- 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. Vesicle may form between the claws of the feet and along the coronary band. There may also appear on the teats and udder – reduced lactation, mastitis and abortion are common. Mortality in adults is usually very low. However, up to 50% of calves can dies due to cardiac involvement, secondary infections, exposure and malnutrition.
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 form on the snout, but tend to rupture quickly. Abortion is common. Mortality in piglets can be high.
In sheep and goats,
the disease is usually milder with fewer lesions. Affected sheep are depressed and reluctant to stand. Some animals may get a 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.
See also…