06/23/2025
Caseous Lymphadenitis (CL) in Goats and Sheep – Suppurative Lymph Node Abscesses
Caseous lymphadenitis (CL) is a chronic and contagious disease caused by the bacterium Corynebacterium pseudotuberculosis. It presents in two primary forms. The external form is characterized by swollen superficial lymph nodes, most commonly in the submandibular, prescapular, prefemoral regions, and occasionally in the upper udder area (supramammary region). The internal form, more prevalent in sheep, leads to progressive weight loss, chronic debilitation, and may involve the lungs, liver, or internal lymphatic structures.
The bacterium typically enters the host through skin wounds resulting from shearing, tagging, castration, or contact with sharp environmental objects, and then spreads via the lymphatic system. It is a highly resilient organism, capable of surviving in soil for up to eight months. The primary source of infection is purulent material discharged from draining abscesses. Even after disinfection and drainage, lesions may continue to shed infectious exudate; therefore, animals must not be released from isolation until the lesion is completely dry.
Clinically, the disease presents as firm, often painful abscesses in superficial lymph nodes, especially in goats. In its internal form, clinical signs may include weight loss, coughing, nasal discharge, and generalized weakness. The purulent material is typically thick, yellow-green, and odorless. These lesions can cause significant discomfort, especially at advanced stages, and pain may alter animal behavior. Many animals will avoid feed bunks due to fear of trauma to the lesion, resulting in reduced feed intake and compromised productivity. In females, abscesses can also develop in the upper udder region, near the supramammary lymph nodes, potentially leading to pain, difficulty nursing, or secondary mastitis.
The maturation stage of the abscess can often be identified clinically in the field. Characteristic signs include focal alopecia over the lesion, dry and taut skin, and in some cases, cracking of the skin surface. Identifying this stage is essential for determining the optimal time for intervention.
Diagnosis is based on bacterial culture of purulent material obtained from the abscess. Serologic testing is also available but must be interpreted with caution and within the context of herd history. In suspected internal cases, diagnostic imaging such as ultrasound or radiography can assist in identifying deep-seated lesions.
Treatment is challenging, as CL is not considered a curable disease. In commercial herds or flocks, it is strongly advised to cull chronically infected animals. Effective management of a CL-infected flock requires a strategic and proactive approach, with long-term commitment and resource allocation. In select cases involving genetically or economically valuable animals, treatment may include abscess drainage, lavage of the cavity with diluted iodine, and administration of systemic or intralesional antibiotics.
According to the field experience of Joseph Lepar, intralesional injection of formalin into the center of the abscess can promote rapid drying, scab formation, and eventual detachment with clean scarring. It is crucial to emphasize that formalin is a hazardous substance and must be handled with full protective gear. The lesion must be confirmed as an abscess, not a lipoma or other mass. The injection should be made from the upper aspect of the abscess to prevent leakage. Only a small volume is required—typically 0.5 to 1 mL depending on abscess size. The injection must be targeted precisely into the abscess core, avoiding any contact with healthy tissue.
Successful control of CL relies heavily on strict biosecurity measures. All equipment used between animals—including shears, scissors, and tagging tools—must be thoroughly disinfected. Sharp environmental hazards such as barbed wire, nails, and exposed metal surfaces should be eliminated. Approved vaccines are available, though they offer partial protection and must only be used according to species-specific labeling and veterinary guidance. Newly introduced animals should undergo a quarantine period of at least three weeks, including a full clinical examination and, when appropriate, serological screening.
In summary, CL is a persistent and highly contagious disease with significant health and economic implications. The most effective approach to mitigation involves early detection, rigorous case management, strict isolation protocols, targeted treatment, and consistent implementation of environmental hygiene and preventive strategies.
**Do not inject goats during pregnancy!!!**
**Do not inject goats during pregnancy!!!**
**Do not inject goats during pregnancy!!!**
