A. bovis was first described in 1877 by Bollinger and Harz, when they isolated the causative agent of lumpy jaw from a cow.[9] Two theories for the source of infection have since been developed.[10] 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. This theory has mostly been supported by clinical observations, and has been hard to demonstrate in a laboratory setting.