What is the origin of the idiom "prick up one's ears" and when to use it?

The idiom "prick up one's ears" dates back to the 16th century and has its origins in the behavior of animals, particularly horses and dogs. When an animal pricks up its ears, it raises them upright, making them more sensitive to sounds and better able to hear what's happening in their surroundings. This action signifies a heightened state of attentiveness and alertness. This expression is used to describe the act of becoming alert, attentive, and eager to listen carefully to something that has been heard or said.