Dogs are more variable in size than any other domesticated animal. The smallest known dog was a Yorkshire terrier that stood 2 1/2 inches at the shoulder, 3 3/4 inches along the head-and-body length and weighed 4 ounces.
The largest known dog was an English mastiff that weighed 343 lbs. and measured more than 8 feet from the snout to the tail. The tallest dog was a Great Dane that stood more than 3 ½ feet at the shoulder.