The big difference with dogs and humans is that dogs are not as interested in seeing the objects that surround them, they rather smell them. Smelling is a way of recognizing the world. Using this sense, you may wonder can dog sense pregnancy ?
Well, likely so, just read one.
The smelling receiver is made up of a mucous, a labyrinth of innumerablefolds that could cover a surface of 130 m2 compared to the 3 m2 that humans have. The dog has 120 to 220 million cells next to man’s 5 million cells. Its smell is so developed that it can detect the lightest environmental change. As a matter of fact, the dog can detect the change of character of other dogs or humans that surround them, just by detecting the slight increase or decrease of their hormonal levels and their sweat. This has nothing to do with a sixth sense: the dog can just detect certain signals that go unnoticed by humans.
Even so, tears of joy contain different substances than those of sadness or pain and dogs are able to tell the difference. The sense of smell of dogs enables them to follow the cent of a wild animal and locate it; track missing persons; search for people buried under decries or snow (they can detect up to seven meters); find underground mushrooms, follow the trace of a criminal or detect hidden drugs. The dog’s nose can smell up to one million times that of a human’s. Through smelling they get all the information they need; and like we use image maps to guide us, they have smell maps.