Animals' sense of smell is astounding. A shark can smell 1 part of blood in 100 parts of water. The elephant can smell water up to three miles away. After cats eat, they immediately bathe themselves, because their instinct tells them to get the food scent off before predators can detect it.

A dog's sense of smell is one of the keenest in nature. Newborn puppies are able to identify their mother by smell alone. And a puppy can identify its siblings by smell at four to five weeks of age. They retain this ability even after separation for 12 months. When a pot of stew is cooking on the stove, a human will smell the stew; the dog will smell the beef, potatoes, carrots, peas, spices and other individual ingredients.

If you unfolded and laid out the delicate membranes from inside a dog's nose, they would be larger than the dog! The estimated number of dog smell receptors is 125,000,000 to 250,000,000 compared to our 5,000,000 to 15,000,000. Air breathed in through the dog's nose passes through two nasal cavities behind the nose. These cavities are lined by a mucous membrane containing many nerve endings that are stimulated by odor molecules.

Canine sniffing ability is particularly evident in the heroic search and rescue dogs at work in the World Trade Center rubble, just as we saw here at the federal building. Most dogs can be trained for search and rescue. Working or sporting breeds are good candidates because they have the stamina, motivation and physical size. The most common breeds used are retrievers, shepherds, hounds and spaniels. The Federal Aviation Administration uses primarily sporting breeds: Labradors, Chesapeake Bay Retrievers and Golden Retrievers. They are chosen for their gentle temperament and keen sensory capabilities.
And their sense of smell is 100,000 times better than ours. Their skills include tracking, trailing, air scenting, cadaver search, water search, article search and scent discrimination.

Dogs can even find land mines. According to Dr. Randall Lockwood, Humane Society vice president for research and education outreach, the threat of deadly mines looms in many war-torn nations. They stop children from going to school and parents from walking to the village market. For every human life taken, an estimated 20 to 50 animals–livestock and wildlife–are killed. The Humane Society endorses recruiting dogs for training, because injuries to the animals that sniff out mines are rare.

The American Forces Press Service states that the most reliable detection method ever found for land mines and other explosives is the dog's nose. Regina Dugan, of the Defense Advanced Research Projects Agency, says the dog's sense of smell is so refined, it can differentiate between very similar odors.

Dogs and other scenting animals detect airborne odors with extraordinary sensitivity. Studies show that a dog stops panting in order to scent, since panting produces a turbulent jet which disturbs scent-bearing air currents. Inspiratory airflow enters the nostrils from straight ahead, while expiration is directed to the sides of the nose and downward. The musculature and geometry of the dog's nose thus modulates the airflow during scenting.

Experiments on the external aerodynamics of canine olfaction (sense of smell) has shown there are two general types of airflow–high-frequency (short) sniffing during close inspection of an object, and low-frequency (long) sniffing of more distant objects. A comparison of the two shows that the dog has some directional control over the turbulent jets generated from its nostrils during expiration. During close inspection of a scent source from above, the nostrils direct the expired air rearward, so that it doesn't impinge upon the object. However, when scanning the vicinity of a scent source on the ground, the motion of the dog's nose can aim its expiratory jets directly at the source.

This research is an attempt to understand the aerodynamics of the dog's sense of smell sufficiently enough to design a mimicking device. In other words, the Defense Dept. is trying to come up with an electronic dog's nose. So far, nothing beats the real thing.

Those amazing noses: they protect our society, assist the elderly, help the disabled, search and rescue and defeat terrorism!

If you have any questions, please feel free to call me at 405-787-1001.

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