Caseous Lymphadenitis
CLA in sheep and goats
By Cleon V. Kimberling, D.V.M.
Oct 27, 2002, 11:36pm

http://www.cvmbs.colostate.edu/dlab/webdocs/ext_vet/cleon10.html
Caseous Lymphadenitis

Caseous Lymphadenitis (CLA) can be a devastating disease for the sheep and goat producer. It can pose a huge economic loss by decreasing pelt value through abscess scars, or with the internal form, a loss through decreased weight gain and general unthriftiness, poor wool harvest or poor milk production. The internal form of disease has been reported as the third most important cause of condemnation of sheep carcasses in the US. Eradication and control of the disease in a flock is of outmost importance for the producer and efforts should be made to reach this goal rather than treatment of infected individuals. Infection should be considered lifelong even if an animal appears to be non-symptomatic.

CLA is caused by the bacteria Corynebacterium pseudotuberculosis, which can survive in the environment for months to years. Infection with this organism causes two forms of disease. Superficial CLA involves the lymphnodes just under the skin. It presents as an abscess or multiple abscesses which can be found around the head and neck or at the junction of the legs and body, that will eventually rupture and drain. The second form, visceral CLA, involves the lymphnodes and organs found in the body cavity, especially the kidney and liver. Infected animals present chronically debilitated, with poor weight gain, lower wool yield and decreased milk production. While both sheep and goats can have either form of the disease, goats tend to get the superficial form more commonly and sheep usually present with the visceral form. Animals less than six months old are less likely to have the disease than older animals. It is thought that this is due to repeated exposure to the organism throughout an animal's life. Infection should be considered lifelong, and affected animals should be treated as such.

Even though there are no cases of humans being infected with this disease in the US, there is always the potential. Cases have occurred in other countries, although these are generally found to be from hand skinning carcasses. Usually the person has injured their hand with an infected knife. Other cases were caused by consumption of raw infected milk. Because of this potential, handling of the body parts of infected animals and especially the pus from abscesses should never be taken lightly.

As mentioned before, control and eradication of CLA are the most important goals for the producer with infected animals. The bacteria can infect animals both through skin contact with infected material and through punctures or scrapes. Because of its ability to infect animals so readily, there are many things for the producer to keep in mind to protect healthy animals. Isolate infected animals from the rest of the herd to prevent spreading the disease. Shear infected animals last, and youngest animals first. Make sure to disinfect any area (feeders etc.) that an infected animal may have used or abscess has drained. Minimize crowding to decrease spread to non-infected animals by seemingly uninfected herd mates. Inoculate all animals yearly with the toxoid vaccine. When buying new animals, make sure they come from CLA-free herds. Control external parasites and have the shearing crew use only the equipment from your farm. By keeping these things in mind, producers will be able to keep CLA from decreasing their economic gains.

Additional pictures of Caseous Lymphadenitis Disorder
CLA Viceral Abcesses
Internal abcess

Prepared by:
Steve Sharkey
Steve Davis
Kevin Inman

For More Information on this topic or to suggest other topics Contact:

Cleon V. Kimberling, D.V.M.
Colorado State University VTH
Fort Collins, CO 80523

E-mail:cleon@coloradolamb-wool.org