Dogs like humans were given their senses as means of protection. Like their human companions a dogs nose is used to locate what is pleasurable and sniff out what could potentially cause us harm. Unlike us a dogs nose is his primary sense. A canines nose is stereoscopic ( his nostrils can pull information scent, distance, place ) thus allowing him to comprehend in seconds his place in the environment. Allowing your pup to do this may save your life and or the life of another living being. The Details h/t NPR via ISU.