Outbreak of fatal salmonellosis in cats following use of a high-titer modified-live panleukopenia virus vaccine.

A 14-week-old kitten from a private cattery was examined because of an acute onset of recumbency and epistaxis 10 days after receiving a high-titer modified-live virus vaccine containing panleukopenia virus, calicivirus, and herpesvirus components. The kitten died the following day, and intestinal crypt necrosis; hepatic, splenic, and lymph node inflammation and necrosis; and pneumonia were seen at necropsy. Salmonella typhimurium was isolated from mesenteric lymph nodes and the spleen. The breeder reported that 4 other kittens had died in the previous month, each within 1 to 2 weeks after being vaccinated with the same modified-live virus vaccine. Carcasses of 3 kittens were available for examination, and Salmonella sp was isolated from mesenteric lymph nodes of all 3. Villus crypt necrosis and secondary fibrosis were also found. Three of the remaining 12 kittens in the cattery were also found to be shedding Salmonella sp in their feces. Clinical and pathologic findings in these kittens were likely attributable to salmonellosis and panleukopenia, and suggest that mild immunosuppression induced by vaccination could have facilitated development of fatal salmonellosis in subclinical carrier kittens. However, we cannot prove that vaccination actually played any role.