5 fascinating dog facts that will surprise you

5 fascinating dog facts that will surprise you A dog’s nose print is unique, much like a person’s fingerprint. Dogs are not colorblind. They also see blue and yellow. All puppies are born deaf. The reason dogs curl up is because of an age-old instinct to keep themselves warm and to protect vital organs while they sleep. The USA is the country with the highest pet dog population, at around 75 million.