Why does my cat keep purring from its throat?

Persistent throat purring in a cat can mean several things: the cat is happy and relaxed and purring comfortably; or during light sleep cats often purr, which helps stimulate muscles and bones and keep them healthy. Additionally, cats may purr under stress—for example, when fractured or in pain. However, if a cat purrs in every situation, the owner should take it to a vet to rule out viral infection.