Causative agent: Actinobacillus lignieresii
The bacterium is found in the mouth of clinically normal ruminants (9). Entry may occur through abrasions of the oral mucosa associated with the feeding of rough or course feed. Disruptions of the oral mucosa resulting from the eruption of teeth may also allow entry of the bacterium.
Clinical signs:
Actinobacillosis has been found in bison but the clinical signs associated with infection have not been described (10). In cattle, Actinobacillosis is commonly called wooden tongue (9). In cattle there is excess salivation, the tongue becoming swollen and hard. Prehension of food becomes difficult and the animal may have difficulty eating with food dropping from the mouth while chewing.
Diagnosis:
The diagnosis is usually made from the clinical signs and, where possible, clinical examination of the oral cavity. Post mortem culture of oral lesions will yield the organism.
Treatment:
There have been no treatment protocols established for the treatment of Actinobacillosis in bison (10). A. ligniersii has been shown to be sensitive to tetracyclines, streptomycin, and erythromycin (9). Long acting antibiotic preparations should always be the first choice when treating bison. Daily handling of sick bison increases the risk of injury to the bison and increases the stress placed on an already sick bison. Multiple, consecutive attempts at corralling and handling of bison can make them refractory to further handling. These animals can become difficult and dangerous to work with. In some cases a single treatment opportunity is all that an upset bison will allow. Bison have a very strong herd instinct. Separating a sick bison into a pen by its self to facilitate handling may not be a good idea. Being alone in a pen often puts considerable stress on bison. In some cases, bison that are penned alone will run or pace up and down the perimeter of the fence for days, without eating or drinking. It is always a good idea to include at least a couple of other bison in the pen with the sick one.
Sodium iodide works well for treating Actinobacillosis in cattle (9). Visible response to treatment often takes 1 to 2 days. The disadvantage of sodium iodide for treating bison is that it must be administered intravenously.
Control:
Actinobacillosis usually occurs as isolated cases. There have been no control protocols reported for bison.