FCV is highly contagious and one of the most common pathogens in domestic cats. Infected cats often show painful erosions in the mouth. FCV plays a role in chronic gingivostomatitis and in juvenile cats it can lead to fatal pneumonia. FCV infections are more common in multi-cat environments and in sick cats, but healthy cats can also be FCV shedders. FCV shows a high mutation rate, which can pose a problem with vaccine immunity. Highly aggressive, virulent-systemic FCV have been identified characterized by severe systemic inflammatory reactions with fever and reduced general health, skin edema and ulcerations, infection of the inner organs and subsequent multi-organ failure and peracute death. For all these reasons, FCV poses a continuous risk to felids and as veterinarians we need to know how to recognize and prevent FCV infections and virulent-systemic outbreaks.