Dogs have a remarkable ability to identify and recall smells, much superior to that of a person. The human nose has just three-square centimeters of olfactory membrane where some dog breeds, like Bloodhounds, have as much as 150 square centimeters of odor-detection stuff within their noses. Dogs also have forty times more odor processing cells inside their brains than people.
Another variable for the dog’s first-class smelling skill is the way it can gather atmosphere in a special chamber of the nose. The atmosphere remains in the chamber when the dog exhales, so smell molecules collect there until there’s a satisfactory concentration accessible for the dog to identify an odor.
Besides having the ability to discriminate between distinct odors, a dog has a fantastic olfactory memory. A dog can recall odors long after being exposed to the initial scent.
Dogs have yet another organ inside their nasal cavity called Jacobson’s organ. This organ’s function can best be called a blend of flavor and odor. Dogs can literally taste the atmosphere. A dog which is experiencing this flavor/odor encounter generally holds his mouth in a semi-open position that resembles a smile.