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dog, carnivorous, domesticated wolf (Canis lupus familiaris) of the family Canidae, to which the jackal, fox, and tanuki also belong. The family Canidae is sometimes referred to as the dog family, and its characteristics, e.g., long muzzle, large canine teeth, and long tail, as canine traits. However, the unmodified term dog usually refers only to the domestic subspecies Canis lupus familiaris.

Two characteristics distinguish the dog from other canids and, indeed, from all other animal species. The first is its worldwide distribution in close association with humans, encompassing both hemispheres from the tropics to the Arctic. The second is the enormous amount of variability found within the subspecies. For example, the Irish wolfhound may stand as high as 39 in. (99.1 cm) at the shoulder, while the Chihuahua's shoulder is usually no more than 6 in. (15.2 cm) from the ground; the silky coat of the Yorkshire terrier may be 2 ft (61 cm) long, while a few breeds of dog (such as the Mexican hairless) are entirely without hair. The evolution of such widely differing breeds has been heavily influenced by conscious human selection, in addition to natural evolution.

Dogs have been selectively bred through the centuries for special purposes, notably to pursue and retrieve game, as draft animals, as guides (e.g., for the blind), and as companions. Although dogs possess hearing abilities far superior to humans', their acute sense of smell is probably the sense most utilized. In addition to traditional hunting and tracking, the dog's sense of smell has been put to such diverse uses as the location of exotic foods and the detection of drugs and explosives, e.g., in luggage and packages.

Dogs can be protected against serious diseases for which vaccines are available; these include distemper, canine hepatitis, leptospirosis, and rabies.

Early Dogs

The dog is descended from the wolf. True wolves appeared in Europe about one million years ago and in the Americas some 700,000 years later. Dog remains estimated to be about 14,000 years old have been found in Germany, and younger remains have been found in Israel (about 13,500 years old) and Idaho (about 10,500 years old). It is probable that the dog was the first animal to become domesticated, certainly by 15,000 years ago, but possibly long before that. Genetic studies comparing dogs with surviving and extinct wolf species indicate that wolves and dogs separated 27,000 to 40,000 years ago, with the implication that domestication may have occurred as early as 30,000 years ago. Domestication may have occurred independently in a number of different areas of the world, but genetic tests show that all dogs are descended from an Eurasian stock, even the now extinct pre-Columbian dogs of the Americas.

It is thought that the earliest domesticated dogs resembled the present-day dingo, the wild dog of Australia. The dingo is believed to have come to Australia as a domestic dog with the aborigines from Southeast Asia. Although more historical information exists on the forerunners of European dogs (such as the British hounds, terriers, and shepherd dogs) than on those of other areas, there is evidence that dogs have existed in most areas of the world throughout the period of recorded history. One of the oldest known breeds is the basenji, which originated in central Africa and is still used as a hunter by certain tribes in that region. Several distinct breeds were known in ancient Egypt and a mastifflike breed (resembling the Kurdish dog in present-day Iraq) is found in Babylonian illustrations of c.2200 B.C.

Dog Breeds

The Purebred Dog

A breed of dog is produced by selecting and mating dogs with certain desired characteristics. The offspring of such matings are then inbred, i.e., mated with litter mates or close relatives. After about eight generations, the line usually breeds true, i.e., most offspring resemble each other. Then standard traits can be established for the new breed. A purebred dog is one that conforms to the standards of a certain breed and whose lineage, or pedigree, has been recorded for a certain period of time.

One of the principal functions of a kennel club is to maintain the records of lineage of individual purebred dogs in order to preserve breed standards. The stud books of the AKC contain entries for all purebred dogs whose owners have elected to register their dog's pedigree. Other stud books, such as those of the United Kennel Club, often record dogs of breeds not recognized by the AKC but which have a considerable following in the United States. Dogs of mixed origin or whose parentage is unknown are called mongrels.

Classification of Breeds

Attempts to classify dogs probably date from the time when humans discovered that certain canine traits were more useful than others. The earliest known system of classification, that of the Romans, included categories for house dogs, shepherd dogs, sporting dogs, war dogs, dogs that ran by scent, and dogs that ran by sight. Today there are systems of classification and breeding in most countries of Western Europe and in North America, many using a variation of the standard British system.

In the United States, the classification system most frequently encountered is that employed by the American Kennel Club (AKC), which recognizes more than 150 of the more than 200 known breeds. The breeds are grouped into six classes. In the sporting dog group are pointers, retrievers, setters, and spaniels. These dogs hunt by air scent as opposed to those of the hound group, e.g., beagles, foxhounds, and bloodhounds, which track their prey by ground scent. Also classified as hounds are those dogs of the greyhound type, e.g., whippets, borzois, and Salukis, which hunt mainly by sight. The many breeds of terrier go to earth after their burrowing prey. Among the working dog group, used as guards, guides, and herders, are the collie, the German shepherd, and the St. Bernard. Such diminutive pet dogs as the Pekingese, the Pomeranian, and the pug belong to the toy dog class. The nonsporting dog group is a class of dogs bred principally as pets and companions and includes the Boston terrier, the bulldog, the chow chow, the Dalmatian, and the poodle. In addition to the breeds in the above classes, the AKC currently places additional breeds in a miscellaneous group; breeds recently recognized by the club are placed in this class until they become established. Included are the Akita of Japan, the Australian cattle dog, the Australian kelpie, the Bichon Frise (a French descendant of the water spaniel), the border collie (an English shepherd dog), the cavalier King Charles spaniel, the Ibizan hound (of Spanish origin), the miniature bull terrier, the soft-coated wheaten terrier (from Ireland), the Spinone Italiano, and the Tibetan terrier.

Dogs registered by the AKC and other registry associations compete regularly in dog shows and field trials. In dog shows, the various breeds are judged solely on appearance, while in field trials they are rated according to their hunting skills.

See articles on individual dog breeds.


Female dogs, or bitches, will mate only when in heat, or estrus, which occurs about every six months and lasts from 18 to 22 days. Whelping (giving birth) occurs after a gestation period of about nine weeks. The size of the litter varies to some extent with the size of the dog: toy dogs rarely bear more than 2 puppies, while the largest breeds average closer to 10.


See E. Schneider-Leyer, Dogs of the World (1960); American Kennel Club, The Complete Dog Book (1968); E. H. Hart, Encyclopedia of Dog Breeds (1968); H. P. Davis, ed., The New Dog Encyclopedia (rev. ed. 1973).

The Columbia Electronic Encyclopedia™ Copyright © 2022, Columbia University Press. Licensed from Columbia University Press. All rights reserved.


(religion, spiritualism, and occult)

The Dog is one of the 12 animals of the Chinese zodiac. It refers to one of the 12 earthly branches that are used in Chinese astrology, together with the 10 heavenly stems. Such a branch designates one day every 12 days: the days are named according to a sexagesimal (60) cycle, made of 10 series of 12 branches.

The Dog is not a jolly fellow. Introverted and ill at ease, he seems to have self-control and to be respectable, but this is a false front. He is shy and loving, and tends to devote himself to noble causes. Modest and without ambition, but courageous and a perfectionist, he does very well with social issues, but not in business. He has a tendency to be pessimistic.

—Michele Delemme

The Astrology Book, Second Edition © 2003 Visible Ink Press®. All rights reserved.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



(Canis lupus familiaris), a mammal of the family Canidae. Dogs are widely distributed throughout the world. Descended from the wolf, they were apparently domesticated during the Me-solithic period (Middle Stone Age; 13th to seventh millennia B.C.). In the process of domestication and breeding, more than 400 breeds of dogs have been developed, differing in size, body structure, hair covering, coloring, and behavior.

Anatomically, dogs are typical carnivores. They have 42 teeth—12 incisors, four canines, and 26 molars—of which the canines, or fangs, are the most developed. The dog is a digitigrade animal. Each front foot has five toes, one of which is a dewclaw. Each hind foot has four toes, although some breeds also have a dewclaw on each hind foot. The stomach is simple. The intestine is short, as in all carnivores. The brain is developed, which makes it possible to train dogs to perform the most diverse tasks. Dogs have keen hearing, good vision, and a highly developed sense of smell. They run, jump, and swim well. Females attain sexual maturity at seven to eight months, and males at ten to 12 months. The female is in estrus (comes into heat) once or twice a year, and the estrous cycle lasts about 20 days. It is advisable to breed the dog between the ninth and 12th day of the estrous cycle.

The gestation period is 58 to 65 days. A litter may contain only one or two pups or as many as 12 to 18 pups, which are born blind, deaf, and without teeth. The auditory canal usually opens between the fifth and eighth day, and the eyes open between the tenth and 14th day. The milk teeth appear between the 20th and 30th day. The nursing period is one to IV2 months. The life expectancy is generally ten to 12 years, although some dogs have been known to live to 16 or 17 years of age. The diet consists primarily of meat, cereals, bread, and vegetables; whole or ground bones, cod-liver oil, and bone meal are given as food supplements.

Depending on their use, dogs are housed in a variety of ways. Purebreds and watchdogs are generally housed in runs containing a wooden doghouse with an overhang. Sheep dogs are generally housed in tents in the summer, so that they are close to the flocks, and in doghouses in the winter. Dogs kept as pets generally sleep in the owner’s house.

Dogs are raised at special kennels, on hunting farms, at working-dog breeding clubs, and by hunting societies; many breeds are also raised by amateur dog breeders.

Modern breeds of dogs are divided into three groups: hunting dogs, working dogs, and house pets. The universally most popular house pet breeds are the small terriers (toy fox, Skye, Sealy-ham, Cairn, border, Kerry blue, Bedlington, and Yorkshire terriers), the miniature pinscher, the schnauzer, the poodle, the French bulldog, the chihuahua, the Japanese spaniel (chin), the Pekingese, the Maltese, and various spitz breeds.

Dogs may suffer from many infectious diseases that can be transmitted to man, including rabies, mange, ringworm, favus, and various helminthic diseases; for this reason, they must periodically be examined by a veterinarian.


Mazover, A. P. Ekster’er i porody sluzhebnykh sobak. Moscow, 1947.
Pupyshev, P. F. Okhotnich’ilegavyesobaki. Moscow, 1949.
Sakharov, N. A. Tekhnika dressirovki sluzhebnykh sobak, 2nd ed. Moscow, 1963.
Posobie po sobakovodstvu, 2nd ed. Leningrad, 1973.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

What does it mean when you dream about a dog?

Dogs participate in the larger meaning of beasts or creatures, all of which can refer to our natural selves, in either the positive or negative sense of “animal.” Dogs, however, as some of the first domesticated animals, can refer to a wide variety of symbolic meanings, from going along with the “pack,” to hunting (dogs “sniff out” the quarry), to loyalty (“man’s best friend”), to abuse (“treated like a dog”), to exhaustion (“dog-tired”), to tenacity (“doggedness”). Also, as animals who guard the underworld, they can be messengers of the unconscious. As with all dream symbols, the tone and setting of the dream indicate which meaning is appropriate.

The Dream Encyclopedia, Second Edition © 2009 Visible Ink Press®. All rights reserved.


(computer science)
A name for the hexadecimal digit whose decimal equivalent is 13.
(design engineering)
Any of various simple devices for holding, gripping, or fastening, such as a hook, rod, or spike with a ring, claw, or lug at the end.
An iron for supporting logs in a fireplace.
A drag for the wheel of a vehicle.
(vertebrate zoology)
Any of various wild and domestic animals identified as Canis familiaris in the family Canidae; all are carnivorous and digitigrade, are adapted to running, and have four toes with nonretractable claws on each foot.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

dog iron, dog anchor

dog iron
A short bar of iron with its ends bent at right angles and pointed so as to hold together the two pieces into which they are driven.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.


ever pictured at feet of saints; “man’s best friend.” [Medieval Art: Brewer Dictionary, 332; Western Folklore: Misc.]
See: Loyalty
Allusions—Cultural, Literary, Biblical, and Historical: A Thematic Dictionary. Copyright 2008 The Gale Group, Inc. All rights reserved.


a. a domesticated canine mammal, Canis familiaris, occurring in many breeds that show a great variety in size and form
b. (as modifier): dog biscuit
a. any other carnivore of the family Canidae, such as the dingo and coyote
b. (as modifier): the dog family
a. the male of animals of the dog family
b. (as modifier): a dog fox
4. a mechanical device for gripping or holding, esp one of the axial slots by which gear wheels or shafts are engaged to transmit torque
5. any of various atmospheric phenomena
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005


Dogs in dreams could symbolize a large variety of ideas and concepts, but mostly they are symbolic of the dreamer’s defensive structure and may represent personal boundary issues. Carefully consider all of the details and the mood in your dream. First, if you have a dog, it may be natural to dream about him. We become emotionally attached to our dogs and we dream about them just as we dream about anything else that is important to us. Otherwise, dogs could symbolize loyalty and hard work. If someone calls you a dog, it is a negative reflection on your personality. If you are being treated like a dog, you are most likely being abused in some way. On the metaphysical level, dogs are considered to be the guardians of the underworld. Finally, dogs could represent the more basic or “animal” parts of our nature and some think that they specifically represent male energy.
Bedside Dream Dictionary by Silvana Amar Copyright © 2007 by Skyhorse Publishing, Inc.