As the biblical legend goes, God bestowed cold, wet noses on dogs for saving Noah’s Ark from sinking.  One of the dogs on the ark discovered water pouring through a hole in the hull. The dog stuck his nose in the small hole to keep water from flooding inside.  A second dog ran off to alert Noah, who quickly repaired the hole. The dogs saved the day. For their actions, God made a cold, wet nose the symbol of good health for a dog.  (If that had been my cats on the ark, they would have stood by the hole and tried to drink the water as it came pouring in!)