Caseous lymphadentitis (CLA)

General description
  • Cheesy Gland (also known as CLA) is a contagious bacterial disease that produces lymph node abscesses in sheep and goats. It can have significant economic impact at slaughter through trimming of carcases and carcase contamination. 
  • Where multiple abscesses are present, carcases will be condemned.
  • On farm impacts can include reduced wool production and weight loss or reduced growth rates. Most flocks have at least one animal affected with cheesy gland.
  • The prevalence of cheesy gland can be as high as 30% in unvaccinated flocks, but as low as 3% in vaccinating flocks. Up to 8% of carcases are identified with cheesy gland at meat inspection.
  • The estimated annual cost to industry is $23 million.
  • A bacterial (Corynebacterium pseudotuberculosis) infection of sheep that causes abscesses in the lymph nodes and lungs.
Clinical signs
  • Most sheep with cheesy gland will show no obvious signs but it is readily detected in the carcase after slaughter.
  • Recently formed abscesses contain thick yellow-green pus.
  • With time the pus dries out and the abscess looks like an onion with concentric layers of solid pus.
  • The most common sites for abscesses are in the lymph nodes on the point of the shoulder, in the groin and in the lungs.
  • Detected in the carcase after slaughter.
  • There is no effective treatment; prevention is the key to control.
  • Vaccination is the most effective strategy. Consider boosters if flock under high challenge.
  • Hygiene at shearing and dipping are also key controls.
  • Shear young sheep first, minimise handling (and treatment) of sheep with wounds (e.g. off shears) and use hygienic methods to handle and treat sheep.
  • Don’t plunge or shower dip sheep without good reason and ensure good dipping hygiene, including time for shearing wounds to heal.
  • Keep time in the yards for recently shorn sheep to a minimum.
  • If an abscess is ruptured at shearing or crutching ensure the handpiece, floor or anything else that is contaminated is disinfected.
  • Maintain good hygiene at marking.
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