How are vesicular diseases in pigs diagnosed? A full analysis of methods and key points

Common vesicular diseases in pigs include foot-and-mouth disease, swine vesicular disease, vesicular exanthema of swine and vesicular stomatitis, all mainly characterized by vesicles on the mouth, hooves and other parts. Clinically, attention should be paid to distinguishing them and treating them according to the symptoms.

1. Foot-and-mouth disease. It affects a variety of animals, mainly even-toed ungulates, and humans can also be infected. Cattle are susceptible, followed by pigs, then sheep, goats and camels, and young animals are susceptible. The sources of infection are diseased animals and virus-carrying animals, and the transmission routes are the respiratory tract, digestive tract and wounds, etc. The epidemic has no seasonality, but occurs more often in winter and spring.

After pigs contract the disease, within 1-2 days, the body temperature rises to 40-41°C, with listlessness, reduced or lost appetite, and small vesicles or erosions appear on the oral mucosa. The coronary band, hoof cleft and hoof heel become locally red, slightly hot and sensitive, and soon millet-sized or broad bean-sized vesicles form. After they rupture, the surface bleeds and erodes. If there is no infection, recovery occurs after 1 week. If secondary infection occurs, in severe cases the hoof laminae and hoof wall may slough off, the affected limb cannot bear weight, and the animal often lies down and cannot rise; erosive patches are commonly seen on the muzzle and udder, especially in lactating sows, where skin lesions on the teats are common. Suckling piglets often die suddenly from acute gastroenteritis and myocarditis, with a mortality rate of up to 60%.

2. Swine vesicular disease. It is caused by swine vesicular disease virus. Only pigs are susceptible; cattle, sheep and other livestock do not develop the disease. The sources of infection are diseased pigs and virus-carrying pigs, and it is mainly transmitted through the digestive tract and wounds. The epidemic has no seasonality, but occurs more frequently in humid and muggy seasons.

In the early stage, the skin is pale and swollen, first seen at the junction between the horn and skin of the coronary band and hoof heel. The vesicles protrude noticeably

3. Vesicular stomatitis. It is caused by vesicular stomatitis virus. The sources of infection are diseased and virus-carrying animals, insects are the transmission vectors, and it is directly transmitted through damaged skin and mucous membranes. Many mammals are susceptible, mainly pigs, cattle, horses and some wild animals, and it mainly occurs in summer and autumn.

At the beginning of the disease, the body temperature rises. After 24-48 hours, vesicular lesions appear in the oral cavity and on the hooves, and soon rupture and form scabs. They mostly occur on the tongue, lips, nose tip and coronary band. When the oral or hoof lesions are severe, feeding is affected, but appetite is not lost. Sometimes ulcers occur on the hooves and the lesions expand, which can cause the hoof wall to slough off and expose a bright red bleeding surface. The course of the disease is about 2 weeks, the outcome is good, and the lesions leave no traces.

4. Vesicular exanthema of swine. It is caused by a calicivirus, and the mortality rate is very low. The symptoms are extremely similar to foot-and-mouth disease, swine vesicular disease and vesicular stomatitis, and it is very difficult to distinguish them, so laboratory diagnosis is needed for differentiation.