Dog anatomy varies more within its species than in any other animal. Despite these differences, dogs all share identical bone and muscle structure. They also all have a circulatory system that transports blood, a respiratory system that takes in oxygen, and a digestive tract that digests nutrients. A dog also has powerful muscles, a strong cardiovascular system enabling speed and endurance and sharp teeth typical of all predators. The domestic dog, as we know it today, is the result of thousands of years of selective breeding. But despite huge differences in physical appearance, all dogs are the same.


1. Body Size

Dogs come in a variety of sizes. Canis (lupus) familiaris ranges in size from the miniature chihuahua to the imposing great dane, which can be the size of a lioness. The largest dog on record is a great dane that measures 7’4’’ in length and 155 pounds in weight. The smallest is a Chihuahua that stands 4 inches in height and weighs 1.5 pounds. The giant breeds like great danes, Newfoundlands and St.Bernards typically can weigh as much as 200 pounds. Miniature breeds such as chihuahuas, Yorkshire terriers, and Shih Tzus usually weigh between 5 and 10 pounds.

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