Research overview: main and accessory olfactory systems in cats

Cats sense chemicals through two partly distinct systems: the main olfactory system for general smells and the accessory, vomeronasal system for pheromones and social signals. This overview surveys the division of labor between them, in which the main system detects the broad world of volatile odors while the accessory system specializes in chemical communication. The two systems have separate receptors, sensory surfaces, and brain targets, yet they cooperate to give the cat a complete chemical picture. The survey relates this dual architecture to behaviors ranging from food evaluation to scent-mark investigation and flehmen. It frames the separation as a recurring mammalian theme that is well developed in cats. Understanding the main-versus-accessory distinction clarifies why some feline chemical behaviors, like sniffing food, differ from others, like flehmen at a scent mark, since each engages a different sensory pathway tuned to different kinds of chemical information.