Did you know dogs have an excellent sense of smell? The particular bundle of nerves related to a dog's nose is 40 times larger than that of a human being. Their nostrils contain up to 300 million olfactory receptors compared to our measly 5 million. This allows dogs to detect faint odors we cannot even perceive, down to parts per trillion. This amazing sniffing ability helps dogs track scents, find food and detect changes in their owners' health.