The dog has been a faithful friend of man for many years. Most of the dogs are kept as pets to do useful work like herding sheep or guarding buildings. Today, there are more than 100 breeds of dog of many colours, shapes, and sizes. Dogs are short-sighted and see only shades of grey. They see a world that is blurred and has no colour. But a dog’s sense of smell is a thousand times better than us.

If the dog passes through one place, it can quickly identify the same place again due to its acute smelling power. Therefore trained dogs are used in the modern security system. They can sniff illegal drugs and culprits. Primarily Customs officers use trained dogs for sniffing out illicit drugs. It is not necessary to open cases or crates – one sniff is enough for a dog, even if the drugs are packed in tins.

In our nasal cavity, there are millions of hair-like cells called chemoreceptors, which are sensitive to smell. These Chemoreceptors are connected to the olfactory bulb in the brain. When we smell something, the particles along with the air reach the chemoreceptors, and they produce electrical impulses in the nerves which will reach the olfactory bulb, then we identify the smell. The smelling power, in fact, mainly depends upon the size of the olfactory bulb. Bigger the olfactory bulb better is the smelling power. Studies have revealed that a dog’s olfactory bulb is bigger than that of a man, this is the reason the dogs have a greater power of smell when compared to human beings.

Another reason is the dog’s nasal cavity is wetter when compared to human beings, which helps in identifying the smells better than us. Dogs make use of a strong sense of smell in feeding, hunting, and identifying enemies.