A dog’s heart beats 70 to 120 times a minute, compared to a human’s which beats 70 to 80 times a minute.
The largest breed of dog is the Irish Wolfhound. The Chihuahua is the smallest, while the St. Bernard and Mastiff are among the heaviest.
Dogs descend from a weasel-sized mammal called Miacis which was a tree-dwelling carnivore that existed over 40 million years ago in the North America and Europe regions.
There are about 700 types of pure breed dogs.
A dog's sense of smell is about 1000 times better than a person's.
A one-year-old dog is as physically mature as a 15 year-old human.