These information sheets are provided for your interest. They should not replace veterinary advice from your veterinary surgeon.

Whilst every effort is taken to ensure the accuracy and completeness of the information provided at the time of writing, your specific circumstances must be discussed before advice can be given.

Lumpy jaw - Actinomycosis

Actinomycosis, commonly called ‘Lumpy Jaw’, is caused by the bacteria Actinomyces bovis, which is a normal inhabitant of the bovine mouth. Actinomycosis is a chronic bacterial disease and is more common in cattle than in goats and sheep. The bacteria enter through cuts and abrasions (i.e. due to teeth eruptions or coarse feed) and migrate to the bone, leading to osteomyeltitis (inflammation and infection of the bony tissues). The mandible is affected more commonly than the maxilla. The defining feature of actinomycosis is the presence of a non-painful swelling under the jaw. This swelling can rupture and drain pus-type, smelly fluid which contaminates the environment.

Clinical Signs

  • Hard, immobile, bony mass on the mandible
  • Late in the disease, draining tracts may erupt
  • Inflammation of the lymph nodes (lymphadenitis)
  • Swelling of the pharynx (back of the throat)
  • Excessive salivation due to pain
  • Abnormal eating, dropping of feed from the mouth, inability to grasp food properly
  • Fever in the early stages of disease


Many affected animals are culled as prognosis is often poor and many animals never fully recover. If culling is not preferred, treatments include iodides and antibiotics (penicillin and streptomycin). Additionally, the affected portion of bone and any associated teeth in the surrounding area can be removed.