Vaccination Strategies for Caseous Lymphadenitis in Sheep and Goats: What Works and What to Expect

Vaccination is considered one of the most practical approaches for controlling caseous lymphadenitis (CLA), particularly in regions where the disease is widespread and treatment is both expensive and ineffective. While immunisation alone cannot eradicate CLA, it plays an important role in slowing disease transmission, reducing bacterial load within a flock, and protecting susceptible animals when incorporated into a comprehensive control programme¹. 

Selecting an appropriate vaccination strategy requires an understanding of the available vaccine types, their expected level of protection, and their limitations. 

Why Vaccination Matters 

Because treatment of established CLA offers limited success, continuous immunisation is regarded as the most suitable approach for disease prevention and control in flocks with high infection rates. Vaccination helps reduce the spread of infection and contributes to a gradual decline in disease prevalence, although complete elimination of the disease should not be expected¹. 

Regular vaccination is particularly important for reducing bacterial circulation within the flock while protecting younger animals as older infected animals are identified and culled. Vaccination programmes should also consider species-specific differences, as vaccine efficacy varies between sheep and goats, making tailored vaccination schedules necessary^2,3. 

Commercial Vaccines 

Commercial CLA vaccines are licensed and available in several countries. Most are toxoid-based formulations that combine inactivated phospholipase D (PLD) from Corynebacterium pseudotuberculosis with antigens from multiple Clostridium species, including Clostridium tetani, Clostridium perfringens, Clostridium novyi, Clostridium chauvoei, and Clostridium septicum. 

Although these vaccines have been available for many years, they do not provide complete protection against caseous lymphadenitis. The immunity they induce is often partial and varies between sheep and goats, limiting their ability to prevent infection in every vaccinated animal. In addition, their safety has been questioned due to reported adverse effects such as fever, lethargy, injection-site infections or abscesses, and reduced milk production^1,4,5. 

Recognising the Limitations 

When discussing vaccination with producers, it is important to establish realistic expectations. 

Current commercial vaccines reduce disease occurrence but cannot completely prevent infection or eradicate CLA from an infected flock. In addition, protection differs between individual animals and between species. 

Safety is another consideration. Reported adverse effects include fever, lethargy, injection-site infections or abscesses, and reduced milk production. These potential reactions should be considered when planning flock vaccination programmes and discussing expected outcomes with producers^1,4,5. 

Emerging Vaccine Approaches 

Several experimental vaccines are being developed to improve protection against CLA. These include bacterin, toxoid, combined, live, and DNA vaccines. 

Among these candidates, combined vaccines containing formalin-killed whole bacterial cells together with PLD-rich supernatant or clostridial toxoids have shown the most promising results, providing complete protection against experimental infections^1,2. 

Although these vaccine candidates continue to show encouraging potential, achieving long-lasting and consistent protection across different animal species and immune responses remains an ongoing challenge^2,5. 

Practical Clinical Insights 

Vaccination delivers the greatest benefit when incorporated into a broader disease-control programme rather than being used as a standalone intervention. Regular immunisation of healthy animals, combined with identification, isolation, or culling of infected animals, offers the most practical strategy for reducing disease prevalence within affected flocks. While current vaccines cannot completely eliminate CLA, they remain an important component of long-term flock health management, particularly in endemic areas where reducing transmission is the primary objective. 

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. 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 

3. Burmayan A, Brundage CM. Caseous lymphadenitis outbreak in a small ruminant herd. Open Veterinary Journal. 2021 Oct 3;11(4):530. https://pmc.ncbi.nlm.nih.gov/articles/PMC8770192/pdf/OpenVetJ-11-530.pdf 

4. Ribeiro D, Rocha FD, Leite KM, Soares SD, Silva A, Portela RW, Meyer R, Miyoshi A, Oliveira SC, Azevedo V, Dorella FA. An iron-acquisition-deficient mutant of Corynebacterium pseudotuberculosis efficiently protects mice against challenge. Veterinary research. 2014 Mar 6;45(1):28. https://link.springer.com/content/pdf/10.1186/1297-9716-45-28.pdf 

5. de Pinho RB, de Oliveira Silva MT, Bezerra FS, Borsuk S. Vaccines for caseous lymphadenitis: up-to-date and forward-looking strategies. Applied microbiology and biotechnology. 2021 Mar;105(6):2287-96. https://pmc.ncbi.nlm.nih.gov/articles/PMC7923401/pdf/253_2021_Article_11191.pdf