The domestic dog has been one of the most widely-kept working and companion animals in human history, as well as being a source of food in some cultures.
The dog has been bred to create thousands of species. They range from the tiniest dog, usually a Chihuahua which can weigh as little as 18 ounces and stand only a couple of inches tall, to the mastiff which can weigh up to 286 pounds or the Irish wolfhound which stands three feet tall.
A dog is classified as a carnivore but that does not necessarily mean that its diet must be restricted to meat alone. Unlike a true carnivore, such as a cat, a dog is able to digest a variety of foods including grains and vegetables.
Not only do dogs differ in size but they come in all kinds of shapes and colors. Some have very long coarse hair, others have curly hair, and some have shiny, smooth hair.
There are many different types of dogs. Most can be classified into the following groups: sporting, non-sporting, working, herding, terrier, toy, and hounds.
The father of a litter is called the sire, and the mother of a litter is called the dam. Offspring are generally called pups or puppies until they are about a year old. A group of offspring is a litter. The process of birth is called whelping. Puppies are born after nine weeks. There can be anywhere from 1 to 24 puppies depending on the size and breed of the dog.
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