Domestic Dog

I

Introduction

Domestic Dog, carnivorous mammal, generally considered the first domesticated animal. The domestic dog (Canis familiaris) has coexisted with human beings as a working partner and household pet in all eras and cultures since the days of the cave dwellers. It is generally believed that the direct ancestor of the domestic dog is the wolf, originally found throughout Europe, Asia, and North America.

II

Breeds

Like other members of the dog family, Canis familiaris exhibits great genetic variability; selective breeding by humans and the process of natural evolution have resulted in the development of the hundreds of breeds found throughout the world today.

A

Breed Distinctions

The breeds differ sharply in appearance, function, and size. Weights vary from that of the smallest lap dogs (680 g/1y lb) to that of the huge working breeds (90 kg/200 lb); heights, usually measured at the shoulder, range from 20 cm (8 in) to 94 cm (37 in). Litter sizes vary correspondingly. Gestation time in all breeds is nine weeks; although the smallest toy dogs produce no more than two puppies, the larger breeds may have litters of more than ten.

Dog breeds are classified in groups; in Britain, the groups are the gundog group; hound group; pastoral group; terrier group; toy group; utility group; and working group. Such classifications, and the breeds recognized within them, vary slightly from country to country. The Kennel Club officially recognizes around 200 breeds classified in the 7 groups, as shown in the accompanying table; from time to time, as certain unofficially recognized breeds become established, they are promoted from a miscellaneous class to official status.

B

Recognizing Established Breeds

Standards of desired sizes, colours, and conformation for each breed are drawn up by committees elected by members of the various kennel clubs specializing in each breed. The standards represent an ideal dog and are used as guides for breeders and dog-show judges in evaluating the quality of each dog. Standards may differ from country to country—not all dogs are developed to serve the same purposes or are judged according to the same rules.