Mycoplasma ovipneumoniae is a species of Mycoplasma bacteria that most commonly inhabits and affects ovine animals. M. ovipneumoniae is a respiratory pathogen of domestic sheep, domestic goats, bighorn sheep, mountain goats, and other caprinae that can both cause primary atypical pneumonia and also predispose infected animals to secondary pneumonia with other agents, including Mannheimia haemolytica. Several mechanisms are involved in the pathogenicity of M. ovipneumoniae, including altering macrophage activity, adhering to the ruminants' ciliated epitheluim via its polysaccharide capsule, inducing the production of autoantibiodies to cilary antigens, and suppressive activity on lymphocytes, all of which are important factors that contribute to the disease in sheep and other small ruminant