Epizooty is the mass spread of infectious diseases among wild and domestic animals in a particular area. The low incidence of animals of a particular infection, which is regularly registered on this territory, called sporadic incidence. The incidence exceeding sporadic, is defined as the epidemic. The spread of the disease in large areas or even in some countries is measured as patootie. If the burden of infectious disease in animals depends on the natural conditions of this area and is registered on the territory permanently, the incidence is defined as entitiy.