Just like humans are identified by their fingerprints, dogs can be identified by their nose prints. Yes, you read that correctly, a dogs nose print is unique to that dog, just like no two human fingerprints are alike. If you look closely at a dog’s nose, you will see lines forming patterns, similar to fingerprints. This raises the question– Can nose prints be used to accurately identify a dog if found without a collar or tags?
Few places in the United States have already adopted dog nose printing as a common way of identifying lost dogs, however the Canadian Kennel Club has been accepting dog nose prints as proof of identity since 1938. The general consensus is that nose printing is a more reliable way of matching identity, as dog tags can easily be lost or maybe stolen.
Read more here: http://www.allpetnews.com/dogs-noseprints-can-be-used-to-prove-identity-just-like-fingerprints