Causative agent: Arcanobacter pyogenes
This bacterium is found almost anywhere in the environment, including most ruminant gastrointestinal tracts (9) The bacterium commonly gains access to the body through cuts and abrasions may also enter the animal through abrasions of the oral mucosa in association with the feeding of rough or course feed. Injury to the rumen mucosa subsequent to rumen overload and acidosis may also permit entry of the bacteria.
Clinical signs:
Abscesses can occur almost anywhere in the body. Subcutaneous abscesses on the hind legs of a 4 to 5 month old bison calf from Alaska were reported (1). Multiple soft tissue abscesses and hepatic abscesses have been described in bison (10). In most cases there is a localized swelling associated with the infection.
Diagnosis:
Abscesses are easily diagnosed by observation and palpation. Aspiration of the swelling yields pus. A culture swab may be taken from margins or edges of the abscess and sent to a diagnostic pathology laboratory for culture and identification.
Treatment:
- Lance the abscesses and flush with betadine or iodine solution.
- Injection of systemic antibiotics may be of limited value. Besides, none of the antibiotics that are commercially available to livestock producers in Canada have been approved for use in bison.
- There has been no information reported on the pharmacology of any antibiotics in bison. In general, most veterinarians who work with bison consider that they will respond to antibiotics in a similar manner to cattle. This may not be the case. Care should be taken when dosages and meat withdrawal times are recommended to bison producers.
Control:
The incidence of this disease is low and the institution of control programs is not often warranted.