Novel viruses may contribute to major causes of feline morbidity and mortality including cancer. The identification of novel viral pathogens can result in improved patient outcomes through specific treatment and even disease prevention through viral control measures such as vaccination. In this session, two novel viruses recently identified in the domestic cat, a gammaherpesvirus and a hepadnavirus (hepatitis B virus) that are candidate feline pathogens based on the known pathogenic role of similar viruses in a broad range of mammals, including humans, will be discussed.