Feline high pathogenicity avian influenza H5N1 infection: past and present

Since 2020, the emergence and global dissemination of high pathogenicity avian influenza (HPAI) H5Nx clade 2.3.4.4b infection has had devastating effects in wild and domestic bird populations, and resulted in spillover events in many terrestrial and marine mammalian species, including susceptible captive big cat collections, and feral and domestic feline species. The recent outbreaks in dairy herds in the USA following proposed exposure to infection from wild birds, with subsequent spread to in-contact mammals, demonstrates successful interspecies transmission of this virus and warrants close monitoring. In this literature review, we provide an overview of HPAI H5N1 infection in feline species to date, focusing on domestic but also captive wild cats, looking at the epidemiology, clinical and pathological presentations and management, and a current perspective on risk, testing and strategies to prevent infection.