Merck Manual

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Pet Owner Version

Actinobacillosis in Dogs


Geof W. Smith

, DVM, PhD, Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University

Last full review/revision Jun 2018 | Content last modified Oct 2020

Actinobacillosis is caused by bacteria in the genus Actinobacillus. Several different forms of disease occur, depending on the particular species of Actinobacillus involved and the type of animal infected. Soft tissue infections are common, and lymph node involvement is frequently a step in the spread of the disease throughout the animal’s entire body. Bony tissue close to infected muscles or other tissue may also be infected.

One type of Actinobacillus occasionally causes tumorous abscesses of the tongue in dogs, a condition often called “wooden tongue.” The organism may also cause abnormalities in soft tissues of the head, neck, limbs, and occasionally the lungs, pleura (membranes lining the chest cavity), and tissue under the skin. The organism is normally found in the mucus of the upper gastrointestinal tract. It causes disease when it gains access to adjacent soft tissue through penetrating wounds. The organism causes localized infections and can spread through the lymphatic (immune) system to other tissues.

This form of actinobacillosis is found worldwide, but is sporadic and thus difficult to prevent. Treatment may include surgical removal of the infected tissue and/or antibiotics.

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