Cats smell each other’s butts because it is a normal feline greeting and a powerful way to gather information about one another. It tells them who the other cat is, how they are feeling, and even whether they might be a potential mate.

How cats “read” smells

Cats have an extremely strong sense of smell and a special organ in the roof of the mouth (the vomeronasal or Jacobson’s organ) that helps them analyze pheromones, which are chemical signals used for communication. When they sniff another cat’s rear, those scent molecules are pulled into this organ and interpreted, which is why you may see a cat pause with its mouth slightly open after sniffing.

What information they get

Around the anus are anal glands that release a unique, strong-smelling secretion for each cat, like a scent ID card. From this scent, cats can learn the other cat’s sex, individual identity, reproductive status, health, and general mood (relaxed, stressed, fearful, etc.).

Social meaning for cats

Butt-sniffing acts like a feline version of a handshake or name tag, especially when cats meet or reunite after time apart. It can also play a role in social hierarchy; the more confident or dominant cat may initiate or control the sniffing, while mutual sniffing can help reinforce familiarity and social bonds in multi-cat groups.