dog

Any carnivorous mammal of the family Canidae, including wild dogs, wolves, jackals, coyotes, and foxes. Specifically, the domestic dog Canis familiaris, the earliest animal descended from the wolf. Dogs were first domesticated around 14,000 years ago, and migrated with humans to all the continents. They have been selectively bred into many different varieties for use as working animals and pets.

Characteristics

The dog has slender legs and walks on its toes (digitigrade). The forefeet have five toes, the hind feet four, with non-retractile claws. The head is small and the muzzle pointed, but the shape of the head differs greatly in various breeds. The average life of a dog is from 10 to 14 years, though some live to be 20. The dog has a very acute sense of smell and can readily be trained, for it has a good intelligence.

Wild dogs

Of the wild dogs, some are solitary, such as the long-legged maned wolf Chrysocyon brachurus of South America, but others hunt in groups, such as the African hunting dog Lycaonpictus (classified as a vulnerable species) and the wolf. Jackals scavenge for food, and the raccoon dog Nyctereutes procyonoides of east Asia includes plant food as well as meat in its diet. The Australian wild dog is the dingo.

In the US, the American Kennel Club sets standards for about 200 registered breeds.

Origins
There is archaeological evidence of dog remains at human burial sites that dates from around 14,000 years ago. US biologists sequenced mitochondrial DNA from dogs, wolves, jackals, and coyotes and were able to trace four separate evolutionary lines to wolves indicating that dogs were probably domesticated from wolves in a number of separate incidents thousands of years earlier than previously thought. Studies conducted by US biologist Robert Wayne in 1998 on mitochondrial DNA indicate that dogs were domesticated from wolves as long as 135,000 years ago.

Behaviour
Like wolves, dogs defend a territory against other dogs – in the case of pets the immediate area round the home – but wander further afield, marking ‘scent posts’ by urinating and by defecating. Dogs bury food, again like wolves, and there are close similarities too in sounds and communication behaviour, aggressive behaviour, courtship, and care of young. Prolonged close confinement or isolation can lead to neurotic behaviour.

Reproduction
The gestation period is 63 days. There are usually 4–8 pups in a litter, though occasionally there can be as many as 20. The young are born blind and remain so for about 10 days.

Diseases
Among the worst diseases of dogs are distemper, paradistemper (hard pad), infectious canine hepatitis (Rubarth's disease), and leptospiral infection, all of which are contagious and dangerous diseases which can, however, be effectively controlled by inoculation of puppies. External parasites cause mange and ringworm, both of which are infectious, whilst internal parasites such as tape- and roundworms may be responsible for a serious breakdown in health unless dealt with effectively. Dogs in certain countries may also be at risk from rabies.

Genome
In 2003 scientists at the Institute for Genomic Reasearch in Rockville, Maryland, reported the draft sequencing of the dog genome, accounting for over 80% of the whole genome. The genome is around 2.4 billion DNA letters long and features 18,473 genes that have human equivalents. One aim of such research is to help in the development of treatments for some of the 350 known canine genetic diseases.

Uses of dogs
Dogs are used in hunting, for coursing and retrieving game. They are also valuable as sheepdogs, keeping the flock together, and as guards. In the Arctic regions dogs are used to drag sleighs and other vehicles across the snow. They have frequently saved people from drowning and from suffocation in snowdrifts. Dogs are also employed as messengers, for tracking criminals, detecting drugs, and as guides for the blind.

History
Canine remains have been found in the Danish kitchen-middens of the Neolithic period side by side with human remains. The friezes of Egyptian temples and many very early Egyptian monuments (dating from c. 3000 BC) were carved with figures of dogs. The Jews of the Old and New Testaments regarded dogs as unclean; this was perhaps a reaction to the worship bestowed upon them by the neighbouring tribes of Egyptians and Syrians. The Egyptians worshipped Sirius, a star which they named ‘dog star’ because of its faithfulness in appearing at a certain season to warn them of the approaching overflow of the Nile. The Greeks made use of dogs in battle as well as for hunting. The Romans classified dogs into three groups: (1) Canes venatici, or hunting-dogs; (2) Canes pastorales, or sheepdogs; (3) Canes villatici, or watch-dogs. Early Britain was renowned for its mastiffs, which, according to the Greek historian Strabo, played an important part in the Gallic wars. During the Middle Ages dogs were used in England chiefly in sport. Dogs have played a useful part in exploration, from the time of Columbus's discovery of America down to more recent Arctic expeditions.

Literature
Dogs are present in the mythology and folklore of the earliest peoples – Fingal's companions Bran and Luath, Cavall ‘King Arthur's hound of deepest mouth’, and Hodain of the Tristram and Iseult story. In Greek mythology Ulysses has the faithful dog Argus in the Odyssey, who recognizes his master after an absence of 20 years. Another dog in Greek mythology was Maera, who, by his prolonged howling, directed Erigone to the spot where her father, Icarius, had been murdered. Maera was placed among the stars by Zeus, where he was known as Procyon (‘little dog’) or Icarius Canis. Another story of canine fidelity is the Dog of the Seven Sleepers, who

accompanied his masters to the cave in which they were confined, and stood on guard by their side for 300 years, without moving, eating, drinking, or sleeping. Muhammad admitted him into paradise under the name of Katmir. In folklore dogs have often been credited with mysterious knowledge of spiritual things, and have sometimes been uncanny friends of such magicians as Cornelius Agrippa. They were also depicted as terrible monsters, such as the snarling, many-headed Cerberus, who guarded the entrance to Hades on the farther side of the Styx.

dog

In computing, reference to a cartoon published in The New Yorker (1993) that showed a dog poised over a computer keyboard remarking to another dog, ‘On the Internet, no one knows you're a dog.’ It is used to illustrate the point that the Internet gives users the opportunity to adopt a different persona, for example many women surf using a male identity.

dog (redirected from throwing to the dogs)

dog

Characteristics

Wild dogs

Origins

Behaviour

Reproduction

Diseases

Genome

Uses of dogs

History

Literature

dog

dog
(redirected from throwing to the dogs)