Are your boarding your pet this holiday season? Here are some important tips to make sure your furry friend is when a cat is frightened, its pupils grow bigger. This is to allow the cat to absorb as much information as possible. When the cat is angry or aroused, its pupils narrow in order to enable it to zoom in on tiny details. Do note, however, that since cats’ pupils also change size according to the light, you should pay attention to its body language when trying to figure out how it is feeling.