M2486

Educational Tips for Farmers: Caseous Lymphadenitis (CL) in Sheep and Goats

Life Cycle

Caseous lymphadenitis (CL) is caused by Corynebacterium pseudotuberculosis.

1. CL enters the body. The animal ingests bacteria through direct contact with abscess secretions or inhalation.
2. CL multiplies and spreads throughout the blood system. Lymph nodes, lungs, liver, and kidneys are just some of the internal organs that could develop abscesses.
3. Once infected, the animal is considered infected for the remainder of its life. The time between infection and symptoms is 2–6 months.

Symptoms

• External abscesses can normally be found behind the ears, under the jaw/neck, on the shoulders, or in the rear flank.
• Internal abscesses are detected through necropsy.
• Chronic weight loss is an indicator of internal abscesses.
• If you aren’t sure an abscess is CL, it is good practice to isolate the animal and take a sample for testing.

Diagnosis

• CL is detected by sight and physical examination.
• The only way to definitively confirm CL is by submitting a sample of the abscess secretions for bacterial culture.
• It is important to consult a veterinarian regarding suspicious abscesses on your animals.

Prevention and Control

• Conduct frequent examinations of the herd.
• Avoid purchasing animals with abscesses or abscess scars.
• Disinfect equipment such as ear taggers, hoof trimmers, and shears.
• Cull infected animals.
• There is no cure for CL, but abscesses must be treated to prevent the spread of the bacteria.
• Antibiotics are ineffective.

Treatment

1. Immediately isolate the animal.
2. Wear PPE such as gloves to avoid contamination, and completely drain the abscess.
3. Make sure it is drained over an easily cleanable surface, such as a concrete floor.
4. Keep the animal away from the herd until the abscess is completely healed. It can take a month or more to heal.
5. Properly dispose of all items that have come into contact with CL.

Zoonotic Transmission and Carcass Impact

• Carcasses with internal abscesses are normally condemned.
• However, some theories suggest cutting away CL-tainted meat will make the meat edible.
• CL is transmissible to humans (zoonotic) and can be spread through infected meat and milk.

The information given here is for educational purposes only. References to commercial products, trade names, or suppliers are made with the understanding that no endorsement is implied and that no discrimination against other products or suppliers is intended.

M2486 (POD-07-25)

By Kathryn Ben, DVM Student, MSU College of Veterinary Medicine, Lindsey Dearborn, 2023 Master’s Graduate, Animal and Dairy Sciences, Leyla Rios, PhD, Assistant Professor, Animal and Dairy Sciences, and Michael Pesato, DVM, Four State Veterinary Services.