Treatment and Flock-Level Control of Caseous Lymphadenitis in Sheep and Goats

Caseous lymphadenitis (CLA) remains one of the most difficult diseases to manage in sheep and goats because of its contagious nature, chronic course, and persistence within infected flocks. Once introduced, infected animals become long-term reservoirs, making eradication challenging. Traditional treatment options have significant limitations, shifting the focus from curing individual animals to implementing effective flock-level control measures that reduce transmission and disease prevalence¹. 

Why Treatment Remains Challenging 

Although Corynebacterium pseudotuberculosis is sensitive to several antibiotics, including penicillin, tetracyclines, and cephalosporins under laboratory conditions, antimicrobial therapy has limited success in clinical cases. The organism is protected within thick fibrous capsules surrounding abscesses, while dense purulent exudate and its intracellular location further restrict antibiotic penetration¹. 

Because of these limitations, prolonged antimicrobial treatment is considered both costly and ineffective for herd-level disease management². 

Managing External Lesions 

For animals with external cutaneous abscesses, treatment is generally reserved for valuable breeding or production animals as an alternative to culling. 

Management typically involves debriding the abscess by removing purulent material or surgically excising the entire lesion. This is followed by parenteral antibiotic therapy for four to six weeks in an attempt to reduce recurrence³. 

Despite this approach, treatment outcomes remain inconsistent. Successful resolution depends on complete elimination of all infectious organisms from the treated lesion while assuming no internal abscesses are present. These factors contribute to the discouraging results frequently reported following conventional treatment¹. 

An alternative approach described for localized infections is antimicrobial photodynamic therapy (APDT). Performed after surgical drainage of affected lymph nodes, APDT showed encouraging results, with no recurrence observed in treated lymph nodes during six months of follow-up⁴. 

Building an Effective Flock Control Programme 

Long-term disease control depends on identifying infected animals before transmission becomes widespread. Since introducing infected or abscessed animals is the primary source of infection, regular clinical examinations and periodic serological testing of all animals should form the foundation of any control programme^5,6,7. 

Animals showing clinical signs or testing serologically positive should be isolated from healthy flock mates and culled because infected animals rarely eliminate C. pseudotuberculosis naturally^5,6,7. 

One reported control programme demonstrated that performing blood testing every three months and removing culture-positive or seropositive animals reduced flock seropositivity from 10% to 0.4% within two years¹. However, veterinarians should also consider the considerable expense of repeated testing and the potential impact of false-positive and false-negative results on both disease control and economic outcomes¹. 

Reducing Environmental Transmission 

Minimising skin injuries and environmental contamination is an essential component of CLA control. Practical measures include using smooth wire fencing, sterilising surgical and shearing equipment, using disposable needles, implementing insect control programmes, and disinfecting wounds with 10% iodine. Housing facilities should be sanitised using 10% formaldehyde to reduce environmental contamination¹. 

Additional management practices, such as isolating young, newly shorn sheep, shearing young animals before older flock members, minimising post-shearing cover time, and reducing ectoparasite dips, further help decrease opportunities for bacterial transmission¹. 

Practical Clinical Insights 

Successful CLA management requires looking beyond treatment of individual animals. Because conventional antimicrobial therapy offers limited benefit for established abscesses, long-term control depends on combining strategic culling, regular flock surveillance, appropriate isolation of infected animals, strict sanitation during husbandry procedures, and measures that reduce environmental contamination. An integrated approach remains the most practical strategy for limiting disease spread and reducing flock prevalence over time. 

References 

1. Dopuđ M, Reil I, Zdelar-Tuk M, Špičić S, Duvnjak S. Caseous Lymphadenitis in sheep and goats–“Cheese Glands”. Veterinarska stanica. 2025;56(3):303-16. https://hrcak.srce.hr/file/462890 

2. de Sá Guimarães A, do Carmo FB, Pauletti RB, Seyffert N, Ribeiro D, Lage AP, Heinemann MB, Miyoshi A, Azevedo V, Guimarães Gouveia AM. Caseous lymphadenitis: epidemiology, diagnosis, and control. IIOAB J. 2011;2(11). https://www.researchgate.net/profile/Alessandro-Guimaraes/publication/285967469 

3. de la Fuente Mancera E, Carrasco AC, Elvira SM. Etiological Agent, Pathogenesis, Diagnosis, Treatment, Measures for Prevention and Control of Caseous Lymphadenitis Disease in the Small Ruminants with Special Reference to Sheep. Journal of Biosciences and Medicines. 2024 May 17;12(5):154-70. https://www.scirp.net/pdf/jbm2024125_122152538.pdf 

4. SELLERA FP, GARGANO RG, LIBERA AM, BENESI FJ, AZEDO MR, RIBEIRO MS, BAPTISTA MD, POGLIANI FC. Antimicrobial photodynamic therapy for caseous lymphadenitis abscesses in sheep: report of ten cases. Photodiagnosis and Photodynamic Therapy. 2016 Dec 19. https://www.academia.edu/download/43107528/2016_APDT_for_caseous_lymphadenitis_abscesses_in_sheep_-_Report_of_ten_cases.pdf 

5. Guimarães AS, Seyffert N, Bastos BL, Portela RW, Meyer R, Carmo FB, Cruz JC, McCulloch JA, Lage AP, Heinemann MB, Miyoshi A. Caseous lymphadenitis in sheep flocks of the state of Minas Gerais, Brazil: prevalence and management surveys. Small Ruminant Research. 2009 Nov 1;87(1-3):86-91. https://www.sciencedirect.com/science/article/pii/S0921448809001850 

6. Windsor PA. Control of caseous lymphadenitis. Veterinary Clinics: Food Animal Practice. 2011 Mar 1;27(1):193-202. https://www.academia.edu/download/45713101/j.cvfa.2010.10.01920160517-6272-r4hlkj.pdf 

7. Baazizi R, Mimoune N, Chahed A, Baroudi D, Ramoul K, Abdul-Hussain AS, Ait Issad N, Khelef D. Prevalencija i identifikacija Corynebacterium pseudotuberculosis u zaklanih ovaca u središnjoj regiji Alžira. Veterinarska stanica. 2024;55(3):289-99. https://hrcak.srce.hr/file/439278