Fatal parvoviral infection in captive cougars (Puma concolor): lessons for improving preventive health in wildlife exhibits

Abstract Feline panleukopenia virus (FPV) is a highly contagious parvovirus that causes acute gastroenteritis, leukopenia, and high mortality in felids. Although domestic cats are commonly vaccinated, FPV continues to threaten captive and wild felids because of its environmental stability, rapid progression, and potential antigenic drift. In June 2022, a one-year-old captive female cougar ( Puma concolor ) at Hongshan Forest Zoo, Nanjing, China, was found dead following a peracute course without prodromal signs. The animal had previously received a trivalent feline vaccine containing feline panleukopenia, herpesvirus, and calicivirus antigens. Postmortem examination revealed perianal fecal staining, oral discharge, pulmonary congestion with peripheral emphysema, a darkened liver, and intestinal mucosal sloughing with petechiae. Histopathology revealed crypt epithelial necrosis, mucosal sloughing, and lymphoid depletion, which was consistent with parvoviral enteritis. Fecal and intestinal samples tested positive for FPV according to the lateral-flow assay and PCR. Viral replication was confirmed in CRFK cells via indirect immunofluorescence, and FPV antigen was shown to be localized to the intestinal crypt epithelium via immunohistochemistry. VP2 gene sequencing (1,753 bp) revealed that the isolate clustered with field strains from domestic cats in Jiangsu and Shanghai, which share near-complete nucleotide identity but differ from the Felocell vaccine strain in three amino acid substitutions (A91S, I232V, and L562V), two of which lie in antigenic loops and may affect antigenicity. No further FPV cases were detected during or after the 14-day observation period, reflecting successful containment through disinfection, relocation, feral cat control, and movement restrictions. This represents the first confirmed fatal FPV infection in a captive cougar in China and highlights the potential for local spillover from domestic reservoirs. The case underscores the need for continuous molecular surveillance, vaccination evaluation, and One Health–based biosecurity to protect susceptible wildlife populations at the human–domestic–wildlife interface.