Pneumonia has frequently been identified as an important mortality factor in bighorn sheep (Ovis canadensis) populations in the western United States. Resulting poor lamb survival and low recruitment rates as well as fatalities in adults may strongly influence population trends. Bacteria, in particular Pasteurella species, are the most frequently isolated pathogens. Predisposing factors allowing bacterial penetration of the mucous membranes of the respiratory tract may be necessary for initial infection and are discussed. The outcome is almost invariably fatal for the individual and serial passage may result in enhanced virulence and devastating epizootics. Previously healthy populations of bighorn in four locations were devastated or destroyed by bacterial pneumonias in 1980.
|
