Research shows that contact between bighorn sheep and domestic sheep and goats can lead to respiratory disease and fatal pneumonia in bighorn sheep. The authors reviewed experimental methods and evidence regarding respiratory disease in bighorn sheep relative to domestic sheep and goats based upon the contact hypothesis and categorized by experimental approach. Although efforts to identify organisms causing pneumonia in bighorn sheep following contact with domestic sheep have identified multiple bacteria species, the complete range of mechanisms/causal agents leading to epizootic disease events are not completely understood. However, based upon the effect of disease transmission, spatial and/or temporal separation between domestic sheep and goats and bighorn sheep is prudent when the management objective is to maintain bighorn sheep populations.
