WATCH: How dogs smell

Man's best friend is known for having a sharp sense of smell, but what is it that makes dogs' ability to sniff out almost anything so formidable?

It turns out that dogs' noses are quite complicated, and the part of the brain dedicated to smell is 40 times larger than that of a human.

It's believed that dogs' sense of smell is so sensitive, they may be able to sniff out stress, anger, pain, along with certain illness and conditions which give off unique odours in humans.

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