All ruminant species, exotic or domestic, captive or free-ranging, are susceptible to disease and death due to Mycobacterium avium subsp. paratuberculosis (MAP) infection. Young ruminants are the most prone to infection through fecal-oral transmission. Fatal Johne’s disease cases have occurred in numerous zoologic hoofstock collections and thus MAP infection is of concern for an industry focused on conserving rare individual animals and their genetics. Diagnosis is best based on MAP detection by PCR or culture in non-domestic species. True nonruminant wildlife reservoirs (ie, a population capable of sustaining the infection independently of reinfection from the initial source and transmitting the pathogen to other species) are rare.