The Dog reference article from the English Wikipedia on 24-Jul-2004
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Domestic Dog
A Norwegian Elkhound, a [[breedEnlarge

A Norwegian Elkhound, a [[breed

of Domestic Dog.]]
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Canidae
Genus: Canis
Species: wolf>lupus
Subspecies: familiaris
Trinomial name
Canis lupus familiaris
Binomial name
Canis familiaris
Dog usually means the domestic dog, Canis lupus familiaris (or "Canis familiaris" in binomial nomenclature). The word is sometimes used to refer collectively to any mammal belonging to the family Canidae (as in "the dog family"), such as wolves, foxes and coyotes. This article deals with the domestic dog.

Dog is also a term used by breeders to specifically denote a male domestic dog. The female is known as a bitch.

Table of contents
1 Ancestry and history of domestication
2 Dog society
3 Dog breeds
4 Interactions between dogs and humans
5 Dog reproduction
6 Miscellaneous Facts
7 Diseases and Ailments
8 Intelligence
9 References
10 Related topics
11 External links

Ancestry and history of domestication

Molecular systematics indicate that the domestic dog is descended from a wolf-like ancestor, and dogs and wolves can still interbreed. The domestication of the dog probably occurred at least 14,000 years ago, and perhaps long before that: there is archaeological evidence of dog remains, showing the characteristic morphological differences from wolves, from at least 14,000 years ago, while wolf remains have been found in association with hominid remains that are at least 400,000 years old. The molecular genetic data suggest that the domestic lineage separated from modern wolves around 150,000 years ago (Vilà et al, 1997).

Dog society

Dog societies are characterized by a companionate hierarchy, in which each individual has a rank in society, and in which there is intense loyalty within the group. Dogs thrive in human society because their relationships with humans mimic their natural social patterns. The dog is always aware of its rank vis-a-vis other individuals in the group, and it may be noted that an assertive dog often considers itself the alpha animal, while considering its human owner to be subordinate.

Dog breeds

There are numerous dog breeds, over 800 being recognised by national dog clubs. A few basic have evolved gradually during the domesticated dog's relationship with man over the last 10,000 or more years, but most modern breeds are of relatively recent derivation. Many of these are the product of a deliberate process of artificial selection. Because of this, some breeds are highly specialized, and there is extraordinary morphological diversity across different breeds. Despite these differences, dogs are able to distinguish dogs from other kinds of animal.

The definition of a dog breed is a matter of some controversy. Some groups use a definition that ultimately requires extreme in-breeding to qualify. Dogs that are bred in this manner often end up with severe health problems. Other organizations define a breed more loosely, such that an individual may be considered of one breed as long as, say, three of its grandparents were of that breed. These considerations come into play among breeders who enter their dogs in dog show competitions.

In February 2004, the Canine Studies Institute in Aurora, Ohio, managed to arrange all breeds of dog into ten categories, according to Darwinian Evolutionary principles. [1]

Mongrels (also known as Muttss) are dogs that do not belong to specific breeds, instead being mixtures of two or more. These are also called mixed-breed dogs. Mixed breeds are in general terms no better or worse than purebred dogs as companions, pets, working dogs, or competitors in dog sports.

Most dogs are capable of and enjoy swimming, but they should be tested in shallow water first to make sure that they do not panic.

Interactions between dogs and humans

The relationship between dogs and humans is ancient. Dogs serve humans in many ways.

Dogs as working partner

There are guard dogs, hunting dogs, and herding dogs. Dogs have served as guides for the blind, as commandos, have flown into outer space (see Laika), and a dog (P.H. Vazak) was even credited as author of an Oscar-nominated screenplay.

Dogs as sporting partner

Many people compete with their dogs in a variety of dog sports, including agility, flyball, and many others. This often strengthens the bond between human and dog, since they must trust one another in a variety of environments and must learn how the other works and thinks.

Dogs as pet

Relationships between humans and dogs are often characterized by strong emotional bonds, which run both ways. Consequently, dogs are popular as pets and companions, independent of any utilitarian considerations. Many dog owners consider having unconditional acceptance from a friend who is always happy to see them to be quite utilitarian, particularly if the dog also leads them to regular exercise. Dogs are quite dependent on human companionship and may suffer poor health without it. Some research has shown that dogs are able to convey a depth of emotion not seen to the same extent in any other animal - this is purportedly due to their closely-knit development with modern man, and the survival-benefits of such communication as dogs became more dependent on humans for sustenance.

The words pooch and poochie are generic, generally affectionate terms for a dog.

Dog lovers may like to read How to choose your pet and take care of it.

A portrait of an adult female cockapoo.

Dogs as food

In certain cultures, dogs are raised on farms and slaughtered as a source of meat. Consequently, the conflicts between dog lovers and dog eaters occasionally appear as headline news. In other cultures, dogs have served as a standby source of food. One example is in China where Chow Chows were often posted to guard family storehouses. During a hard season when the food store was depleted, the dog would be then slaughtered as an emergency ration.

See also Gaegogi.

Dog reproduction

Puppies enjoy teething on almost anythingEnlarge

Puppies enjoy teething on almost anything

Unlike undomesticated canine species, where the females typically come into estrus (also called in season or in heat) once a year, usually in late winter, and bear one litter of young, the female of the domestic dog can come into season at any time of the year and usually twice a year. Most dogs come into season for the first time between 6 and 12 months, although some larger breeds delay until as late as 2 years. The amount of time between cycles varies greatly among different dogs, but a given dog's cycle tends to be consistent through her life.

Dogs bear their litters roughly 9 weeks after insemination.

An average litter consists of about six puppies, especially for breeds that have not strayed too far from their wild ancestors. However, litters of many more or only one or two puppies are also common. Some breeds have a tendency to produce very large litters. Since a mother can provide milk for only a few of those puppies, humans must assist in the care and feeding when the litter exceeds eight or so.

Some breeds have been developed to emphasize certain physical traits beyond the point at which they can safely bear litters on their own. For example, the Bulldog often requires artificial insemination and almost always requires cesarian section for giving birth.

Puppies often have characteristics that do not last beyond early puppyhood. For example, eyes are often blue when they first open but change to other colors as the puppy matures. As another example, Kerry Blue Terrier puppies have light-colored coats when they are born and their distinctive "blue" color appears gradually as the puppy nears maturity. The ears of erect-eared breeds such as the German Shepherd Dog are softly folded at birth but straighten as the puppy grows.

Miscellaneous Facts

Dogs and the Zodiac

The Dog is one of the 12-year cycle of animals which appear in the
Chinese zodiac related to the Chinese calendar. It is thought that each animal is associated with certain personality traits. See: Dog (Zodiac).

Sirius, the Dog Star, is the brightest star in the night sky.

Dogs and Perspiration

A common misconception is that dogs do not sweat. Primarily, dogs regulate their body temperature in a completely different way, through their tongue. That is why after a dog has been running or on a hot day you will see its mouth wide open and tongue hanging out. In addition, dogs effectively sweat through the pads of their feet. Again, on a warm day and after exercise even on dry ground or pavement, you can see a dog's wet footprints on a smooth floor.

A Fine Sense of Direction

It has been observed that a lost dog can often find its way home, sometimes travelling over long distances. It is believed that dogs and cats know the correct position of the sun at their homes. When lost, the animal notes the angle of the sun as it travels, and moves in the direction that indicates that the angle is becoming correct.

Diseases and Ailments

Most diseases that affect dogs or humans are not transferable between the two species. There are some exceptions: Genetic conditions are a problem in some dogs, particularly purebreeds.


Dogs and chocolate

Chocolate in sufficient doses is lethally toxic to dogs (and, for that matter, to horses) and should never be fed to them. This is because chocolate contains theobromine, a chemical stimulant which, together with caffeine and Theophylline, belongs to the group of Methylxanthines. Dogs are unable to metabolize theobromine effectively. If they eat chocolate, the theobromine can remain in their bloodstream for up to 20 hours, and these animals may experience racing heartbeats, hallucinations, severe diarrhea, epileptic seizures, heart attacks, internal bleeding, and eventually death. A chocolate candy bar can be sufficient to make a small dog extremely ill or even kill it. In case of accidental intake of chocolate by a dog, contact a veterinarian or animal poison control immediately; it is commonly recommended to induce vomiting within two hours of ingestion. (Note that carob treats are often available as dog treats; these are unrelated to chocolate and are safe treats).


Dogs are generally valued for their intelligence.

Anecdotal evidence suggests that dogs have a reasonably high intelligence, and scientific studies have confirmed this. Recent examples would include animal psychlogist Juliane Kaminski whose paper in Science demonstrated that Rico, a Border Collie, could learn over 200 words. Rico could remember items' names for four weeks after last exposure (Kaminski eliminated the Clever Hans effect using strict protocols).

Rico was also able to interpret phrases such as "fetch the sock" in terms of its component words (rather than considering the utterance to be a single word): he could give the sock to a specified person.

For more discussion on what dog intelligence is, see Obedience training.


Related topics

External links