Pheromones are chemical messengers used for communication between members of a species. The pheromones emitted by one individual can affect and change the behaviour of other individuals of the same species. In mammals, all lactating females release substances called appeasing pheromones, whose function is to calm and reassure the offspring. Canine appeasing pheromones are secreted by the sebaceous glands of the intermammary sulcus in the lactating bitch, These pheromones calm the puppy at times of stress and provide reassurance, particularly in unknown environments and when encountering novel experiences. Research has shown that the reassuring properties of these pheromones persist even into adult age.