Much of a cat's communicaton is chemical. We cannot fully understand this form of communication, because we lack the organ of perception, the vomeronasal organ, which they use to percieve pheromones. This special sensory organ is located at the top of your cat's hard palate, with the duct openings just behind the incisor teeth. When he or she senses with this organ, they often sniff and then have a far off look in their eye. You may notice them slightly lift the upper lift.
Cats leave chemical messages for eachother, often deliberately, which can then be read much later by another cat. This is most analagous to an e-mail message, which once sent, cannot be modified. The reader then percieves the message, and may leave a response which can be read immediately or some time later.
While there are over 100 chemicals involved in pheromone communication, we are most interested in the "peace, harmony and good tidings to you" pheromones, which have been isolated and synthetically produced by a French company. With in-wall diffusers, and concentrated bottle spritzes, we satuate A Cat's View Veterinary Hospital with these pheromones of peace. So, not only is there the lack of the scent of canines, but there is a definite positive message in the air!