What does 'epizootic' mean in relation to disease?

The term 'epizootic' refers specifically to a disease that occurs in high numbers within a particular animal population, but it is not permanent or consistently present. Instead, an epizootic event indicates that the disease has spread rapidly and widely within that group, often due to an outbreak that may be temporary. This concept is similar to an epidemic in human populations, wherein a disease emerges and affects a large number of individuals within a specific time frame.

In contrast, a disease that is consistently present would be described as endemic, rather than epizootic. The option regarding a disease prevalent only in birds is too narrow, as epizootics can affect various types of animals, not just one species. Additionally, describing a disease restricted to one region does not fully capture the transient and widespread nature of an epizootic occurrence, as the term typically encompasses broader geographical areas and is characterized by its sudden rise in cases. Therefore, the definition that aligns with the term 'epizootic' is that it is a disease that is widespread and temporary within an animal population, making option C the correct understanding.