Lumpy Skin Disease (Pseudo-urticaria, Neethling virus disease, exanthema nodularis bovis, knopvelsiekte)
Description Acute pox viral disease of cattle manifested with sudden appearance of nodules on the skin.
Lumpy skin disease is caused by a capripoxvirus and is characterized by the eruption of variably sized nodules on the skin, edema of one or more limbs, swelling of the lymph glands, and necrotic plaques in mucosae. Secondary problems include pneumonia and infertility. Lumpy skin disease is not highly contagious and has a low mortality rate.
Lumpy skin disease virus causes inapparent to severe disease in cattle. All ages of cattle can be affected, but young calves are usually more severely affected (Fig.).
The severity of the disease depends on the dose of the inoculum as well as the susceptibility of the host (Bos taura is more susceptible than Bos indicus) and the route of exposure. A fever 104 to 107o F (40-41.5o C) can occur and can be transitory or last up to 4 weeks. Generally within 2 days after the appearance of the fever, swellings or nodules 1 to 5 cm in diameter appear in the skin and generalization occurs. Depression, anorexia, excessive salivation, oculonasal discharge, agalactia, and emaciation are presented. Nodules 1 to 7 cm in diameter may occur anywhere on the body but especially in the skin of the muzzle, nares, back, legs, scrotum, perineum, eyelids, lower ear, nasal and oral mucosa, and tail. The hair stands erect over early skin lesions. The nodules are painful and involve the epidermis, dermis, and subcutaneous tissue and may even involve the musculature. As the disease progresses, the nodules become necrotic, and eventually a deep scab forms; this lesion is called a sitfast (Fig.).
Where extensive generalization occurs, animals can become lame and reluctant to move because of edema. Lameness also may result from inflammation of the tendons, tendon sheaths (tendosynovitis), joints (synovitis), and laminae (laminitis). Severe edema in the brisket and legs can occur. If secondary bacterial infection develops in the tendon sheaths and joints, pemmanent lameness may result. Superficial lymph nodes such as the mandibular, parotid, prescapular, and prefemoral nodes, draining affected areas of skin become enlarged 4 to l0 times normal size. Abortion may occur as the result of prolonged fever. Davies has reported intrauterine infection of late-term fetuses in which calves are born with LSD lesions. Temporary or pemmanent sterility in bulls can result from the fever or lesions of the reproductive organs. Cows may not come into estrus for several months after LSD (7). The lesions may persist in various stages over a course of 4 to 6 weeks. Final resolution of lesions may take 2 to 6 months, and nodules can remain visible 1 to 2 years. Permanent damage to the hide is inevitable in clinical cases.