What bovine practitioners need to know about caseous lymphadenitis

Abstract

Caseous lymphadenitis (CL) is one of the costliest, but most under-appreciated infectious diseases of sheep and goats, often leading to premature culling or death. Corynebacterium pseudotuberculosis in sheep and goats results in lifelong infection, with reoccurring abscesses of the peripheral and/or internal lymph nodes and the associated clinical signs. Transmission is by direct contact and indirectly by contamination of feeders, equipment, and the environment. Diagnosis is by abscess culture or necropsy. The serologic test has limitations but can be used to detect exposure to the organism; it may be used to facilitate segregation or culling in herds with low incidence of CL or to exclude introduction of infected animals. Premises hygiene, vaccination, segregation of herd by disease status, and isolation of clinical animals during treatment are the main strategies used to control CL in heavily infected herds. Intensive management of clinical abscesses with early detection ofripening abscesses, animal isolation until the abscess is healed, lancing abscesses in an isolation environment, and preventing cross-contamination of premises and potential fomites are keys to successful management. Vaccination can be used to reduce the number of animals with abscesses and the number of abscesses per animal, thereby reducing the overall herd exposure in endemic herds. Control and eradication of CL requires longterm commitment to an integrated management approach to reduce environmental contamination and prevent direct transmission in the herd or flock.