Mandibular Osteomyelitis

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Also known as: Lumpy jaw — Actinomycosis


bovine actinomycosis, 3-years-old bull, 2-month evolution. (L. Mahin 2008, Wikimedia commons)

Lumpy jaw is a chronic infectious condition which affects cattle. It is caused by the anaerobic filamentous bacteria Actinomyces bovis.

Actinomyces is a normal commensal of the oral cavity, upper respiratory tract and digestive tract of cattle, it gains entry to underlying soft tissues when the mucosa is damaged by trauma or eruption of teeth. It causes an inflammatory reaction, the connective tissue proliferates and is followed by infiltration of leukocytes which results in the formation of a walled off granuloma. The granuloma invades the bones of the head, in particular the mandible, and continues to grow in size. Lesions are characterised by gross swelling, abscesses and draining fistulae overlying granulation of the mandible and maxilla. In some cases the oesophagus and oesophageal groove may become involved but the lymph nodes are not affected.


The condition affects cattle 2-5 yrs old. It is found worldwide but is most prevalent in Western and mid-western states of the USA.


The condition is easily diagnosed on clinical signs and can be confirmed by crushing and staining the yellow granules expressed with the pus from skin lesions to reveal gram-positive filamentous rods.

Clinical signs

  • Facial distortment
  • Granuloma formation overlying the mandible and maxilla
  • Fistulae draining small amounts of thick pus with yellow granules
  • Difficulties with mastication
  • Loose teeth
  • Dyspnoea


Osteomyelitis of the bones of the head with surrounding granulomatous tissue and fistulae draining pus containing small yellow granules.


Treatment is difficult due to the nature of the lesions and poor antibiotic penetration to the site of infection. In less severe cases where infection of the bones is not advanced treatment with penicillin or tetracyclines is recommended. Previously it has been suggested that systemic treatment with potassium iodide is successful but this is no longer recommended due to food safety concerns.


Treatment is rarely successful in advanced cases and recurrence of lesions is common; slaughter is advised.

Literature Search

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Mandibular Osteomyelitis publications


  • Andrews, A.H, Blowey, R.W, Boyd, H and Eddy, R.G. (2004) Bovine Medicine (Second edition), Blackwell Publishing
  • Merck & Co (2008) The Merck Veterinary Manual (Eighth Edition) Merial