Dog's Smell - One of kennest in nature

A dog’s sense of smell is 1,000 times stronger than humans.
A dog's sense of smell is one of the keenest in nature. 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.

Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Canidae
Genus: Canis
Species: C. lupus
Subspecies: C. l. familiaris

Dog's nose consists of 120 to 220 million cells compare to humans with just 5 million cells, also their smelling receiver made up of mucous cover an area of 130 square compare to human with jast 3 square meter. Dogs can detect even lightest environmental changes, a distant object, also even changes in hormonal levels around them. They can sense signals many other things around unnoticed by humans through their noses.

Important use of dog's acute smell sense is detection. They can tract missing persons, search for buried people under decries or snow, they can trace criminals or escaped prisoners through smelling their tract. Military use police dogs to detect drugs and explosives or buried mines in wars.

About Dogs : Wikipedia

The dog (Canis lupus familiaris) is a domesticated subspecies of the wolf, a mammal of the Canidae family of the order Carnivora. The term encompasses both feral and pet varieties and is also sometimes used to describe wild canids of other subspecies or species. The domestic dog has been one of the most widely kept working and companion animals in human history, as well as being a food source in some cultures. There are estimated to be 400 million dogs in the world. The English word dog can be traced back to the Old English docga, a "powerful breed of canine". The term may derive from Proto-Germanic *dukkōn, represented in Old English finger-docce ("finger-muscle").