The bacteria Actinomyces that causes this disease occur in the nose and mouth of the dog. More than one species of Actinomyces are known to cause this disease in them.
Actinomyces bovis causes infection in the soft tissue of the mouth when these bacteria are introduced through wounds in the mouth. The injury usually happens when the dog runs in the underbrush with its mouth open or when it carries objects with sharp edges in its mouth. If the infection spreads to the adjacent bones, the dog’s face may get distorted or teeth may become loose. It may result in difficulty in chewing. Swollen nasal passage may make breathing difficult too.
The condition is difficult to treat in advanced stages. When the facial bones are severely affected through long-term infection, antibiotic treatment rarely succeeds, as the drugs do not penetrate into the affected area. If detected early, an antibacterial drug may be prescribed.
Actinomyces hordeovulneris affects the spleen and liver of dogs, causing abscesses. It can cause inflammations in the dog’s stomach lining and in the cavity around its lungs. Bacterial arthritis also may result. Particles of foxtail grass belonging to the Hordeum spp. are thought to be responsible for introducing the bacteria into the dog’s tissues when they penetrate the skin. The condition has to be treated with long-term antibiotic therapy after draining the abscesses through surgery.
Actinomyces viscosus is another species that infects dogs causing pneumonia. The cavity around the lungs become inflamed and abscesses develop beneath the skin. They usually develop from bites that the dog gets. If the infection is limited to the tissue underlying the skin, it can be successfully treated with antibacterial drugs. Chest inflammations need to be detected early and treated with antibiotics to have any success.