[3] A. bovis normally populates the gastrointestinal tract of healthy ruminants, but is opportunistic in nature and will move into tissues through ulcerations or abrasions of the mucosa to cause infection.

[5] Actinomycosis is pathognomonic for abscesses containing "sulfur" granules, and its colonies appear basophilic with club-shaped reaction products on a histological preparation.

[6][7] Lumpy jaw is commonly treated with broad-spectrum antibiotics with varying success,[8] and can be a major economic loss for producers in countries where it is endemic.

[11] The first is called the exogenous theory and was developed by Bostroem in 1891, when he suggested infection is caused by a foreign body, such as hard hay or grass awns.

[12] A. bovis has been isolated from tonsillar crypts, infected teeth, and dental scum of normal mouths from human and animal patients.

Several researchers have tried to establish the infection in live animals with isolated bacterial cultures, but the results have been mixed, with some seeing development of disease[15] and some seeing no change.

[18] The bony lumps are usually not painful and can develop over weeks to months, causing facial distortion, dyspnea, and occasionally loose teeth.

[20] To diagnose lumpy jaw, the fluids exuding from the bony lump or other abscesses are sampled or aspirated if the infection has not broken through the skin.

[20] A. bovis can be identified histologically by its basophilic colonies and club-shaped reaction product visible in neutrophilic granulomatous lesions.

[17] These granules are small, yellow clumps of exudate that are visible to the naked eye with a similar appearance to grains of sulfur, and are mainly composed of bacterial filaments and host calcium phosphate.

[21] Initial treatment involves surgical debridement of purulent and soft-tissue lesions followed by daily cleaning and flushing of the infection site with saline and povidone-iodine solution, respectively, for about 1 week.

[21] Common causes of trauma to the oral mucosa include consumption of abrasive feed or foreign bodies (thorns, wire, etc.