| Livestock Disease Summaries | नेपाली भाषा |
Caseous Lymphadenitis in Goats and Sheep
Caseous lymphadenitis (CL) is a chronic, infectious disease caused by the bacterium Corynebacterium pseudotuberculosis. This disease is found worldwide and is a major problem for small ruminant producers.
Clinical Signs of CL
CL is characterized by abscess formation in or near major lymph nodes, either externally (near the surface of the body) or internally (within body cavities). CL abscesses usually feel like hard lumps at the site of major lymph nodes. As the abscesses continue to enlarge, they can break open and drain pus, which contaminates the environment and can infect other animals. Ruptured abscesses can appear to heal but then come back at the same or other sites many weeks later. Common locations for lymph node abscesses from CL are shown in the pictures below.
Common locations for CL abscesses
Examples of goats with CL
If the abscesses are inside the body, the animal usually shows chronic weight loss and poor general health. This form of disease may be suspected if other animals in the herd or flock have been diagnosed with CL but is diagnosed by finding internal abscesses at post-mortem examination.
Transmission of CL
When an external CL abscess breaks open, the pus that drains has large numbers of Corynebacteria that contaminate the environment and can persist for long periods of time. These bacteria can then infect other animals. The most common site for entry into the animal is through the skin after injuries, ear tagging, or castration. The bacteria can also infect an animal that inhales them.
Human infection with Corynebacterium pseudotuberculosis is not common but does occur. Wear gloves when handling animals with this disease.
Diagnosis of CL
Finding a hard lump in the location of a lymph node, as shown in the figures above, usually provides a good diagnosis of CL, but other bacteria can cause similar abscesses. It is therefore useful to obtain a more reliable diagnosis using the following techniques:
- Clip the fur over the abscess and disinfect with alcohol. Wear gloves.
- Insert a 18 gauge needle attached to a syringe into the middle of the abscess and draw back to sample the pus inside. You may need to move the needle back and forth. The pus in a CL abscess is very thick, so do not expect to drain the abscess – you may only get a small amount of pus back in the needle. If the pus is very liquid, it is probably not CL.
- Re-cap the needle carefully and submit it to a diagnostic lab for culture or staining.
Treatment and Control of CL
CL should not be considered a curable disease. This disease is very challenging to treat because the abscesses are surrounded by a thick capsule that makes is difficult for antibiotics to penetrate to the inside. If the goal is to prevent CL from spreading within a herd or flock, infected animals – especially those with draining abscesses - should be eliminated to prevent other animals from becoming infected.
Possible treatments for CL if the owner requests treatment:
- Clip the hair over the abscess and open it with a scalpel to drain the pus – be careful to avoid contaminating the environment with the pus. Carefully swab the inside of the open abscess with a strong disinfectant like 7% iodine. Swab with disinfectant for several days and isolate the animal from other non-infected animals.
- Inject with abscess with iodine, oxytetracycline or tulathromycin before it breaks open. This is not a very effective treatment but may help in some cases.
- Systemic treatment with antibiotics is not likely to be effective.
Recommendations for prevention of CL:
- Carefully examine new animals for signs of the disease and do not allow animals with visible abscesses into your herd or flock.
- Eliminate infected animals.
Vaccination
Different types of vaccines for CL are available in several countries, especially for use in sheep. These vaccines are not considered highly effective and certainly do not aid in treatment of CL. They can however help decrease the incidence of this disease in groups of sheep or goats.
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