Canine distemper epizootic in lions, tigers, and leopards in North America.
Canine distemper virus (CDV) infection occurred in captive leopards (Panthera pardus), tigers (Panthera tigris), lions (Panthera leo), and a jaguar (Panthera onca) in 1991 and 1992. An epidemic affected all 4 types of cats at the Wildlife Waystation, San Fernando, California, with 17 deaths. CDV-infected raccoons were thought to be the source of infection in these cats. Two black leopards died at the Naibi Zoo, Coal Valley, Illinois, and 2 tigers died at the Shambala Preserve, Acton, California. Initial clinical signs were anorexia with gastrointestinal and/or respiratory disease followed by convulsions. Canine distemper virus was isolated from 3 leopards, 3 tigers, and 3 lions that died or were killed when moribund. Monoclonal antibody testing identified the virus isolates as CDV. Gross and histopathological findings were similar to those found in canids with distemper with a few exceptions. There were fewer lesions in the brain, and there was a pronounced type 2 cell proliferation in the lungs, with inclusion bodies and CDV antigen demonstrated by immunohistology. Neutralizing antibody to CDV was found in high titres in serum from most animals but was absent or was found only in low titres in some cats that succumbed after CDV infection. There was a marked difference in neutralizing antibody titres when tests were done with different strains of CDV.