Article in ABGA Boer Goat Magazine - Sept/Oct 2001
by Lionel Dawson, D.V.M.
Caseous Lymphadenitis (CL) is a chronic contagious disease affecting mainly sheep and goats This disease is also called pseudobulerculosis or often "abscesses," and has been referred to as the curse of the goat industry throughout the world.
CL is an infection of goats, caused by Cory nebacterium pseudotuberculosis. It is also referred to as "abscesses", because of the peripheral swelling, rupture, and drainage of pus from affected lymph nodes. The prevalence of CL in the commercial goat herds may be as high as 30%. If abscesses affect more than one lymph node, the carcass will be condemned at slaughter. Decreased body weight and milk production also occurs, and reproductive efficiency is often lower when these animals have developed internal abscesses.
Most commonly, symptoms are palpable enlargements of one or more of the superficial lymph nodes. The morbidity of the infection rate in goat flocks increase with age, and may approach 70%.
The enlarged lymph nodes have a very thick wall and are filled with thick greenish pus. The most common lymph nodes affected are mandibular (A in figure 1), prescapular (B), prefermoral (C), and supramammary (D) lymph nodes. Less common is involvement of lymph nodes internally in the chest and abdomen. As the animal gets older, abscesses often develop around the lungs, heart, liver, kidney, and spinal cord. They may cause weight loss, pneumonia, and neuoligical signs.
C. pseudotuberculosis is spread in the environment by broken and draining external abscesses. The organism survives in the environment for at least one year and can be spread on such items as shearing blades, fences, and feeders. The organism enters the goats body through small breaks in skin or mucous membranes and eventually becomes localized in a regional lymph node. Heavy environmental bacteria contamination occurs in confinement operations and around feeders, goat dairies seem to have a high prevalence of CL. There is some evidence that the organism can penetrate intact skin and mucous membrane.
Herd eradication requires diligent management.
A vaccine is available and should be considered in management of CL in infected herds. Vaccine should be considered if you're previously described eradication methods haven't worked or failed. Colorado Serum Company is marketing Caseous-DT, an immunoprophylactic product composed of formalin-killed organisms and toxoided culture supernatant fluid. (Also contains toxoids for clostridium perfringens type D and tentanus toxin.) Which has an efficiency of 70-80% in preventing the clinical manifestations of the disease.
The vaccine may cause severe reactions in infected animals, and also interferes with serologic testing for CL.