Dog

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Dog is a member of Carnivorous Mammals which includes Wolf, Fox, Jackal etc. In fact Dog is a domesticated form of the Gray Wolf and is a member of the Subspecies 'Canis lupus familiaris'. Palaeontologists and Archaeologists have determined that about 60 million years ago, a Small Mammal, similar in appearance to a Weasel, lived in some parts of Asia. It is called Miacis, the Genus that became the ancestor of the Animals known today as Canids: Dogs, Jackals, Wolves and Foxes. Miacis did not leave direct descendants, but Dog-like Canids evolved from it. By about 30 to 40 million years ago Miacis had evolved into the first True Dog - namely, Cynodictis. This was a medium-size Animal, longer than it was tall, with a long tail and a fairly brushy coat. Over the millennia Cynodictis gave rise to two branches, one in Africa and the other in Eurasia. It is considered that Dogs were first domesticated by man, 10,000 to 15,000 years ago. It is not clear as to how Humans domesticated the Dog. It is widely considered that early Humans used Wolves during the hunt, for keeping flocks together and to warn against approaching enemies. Humans in turn, made sure his Wolves were fed. Also, considered is the fact that Wolves are social Animals and this trait made the Wolf to be made as Companion and Wolves on their part considered Man to be his leader, just like it would live in a Pack. The Early Dog diverged into only a handful of Landraces, groups of similar animals whose morphology and behaviour have been shaped by environmental factors and functional roles. As the modern understanding of genetics developed, humans began to intentionally breed Dogs for a wide range of specific traits. Through this process, the Dog has developed into hundreds of varied breeds, and shows more behavioural and morphological variation than any other Land Mammal. The term 'Dog' is used for both Feral and Pet varieties. The Domestic Dog has been one of the most widely kept working and companion animals in human history. The Female Species of a Dog is known as Bitch and group of offspring is known as a Litter. The typical lifespan of Dogs varies widely among breeds, but for most the median longevity, the age at which half the Dogs in a population have died and half are still alive, ranges from 10 to 13 years. There are estimated to be 400 million Dogs in the world.

All Dogs are genetically very similar, Natural Selection and Selective Breeding have reinforced certain characteristics in certain populations of Dogs, giving rise to Dog Types and Dog Breeds. The terms Dog Breed and Dog Type are sometimes used interchangeably, but they have different meanings.

Dog Types - These are broad categories based on function, genetics, or characteristics.

Dog Breeds - These are groups of animals that possess a set of inherited characteristics that distinguishes them from other animals within the same Species. Modern Dog Breeds are Non-Scientific Classifications of Dogs kept by modern kennel clubs. Pure bred Dogs of one breed are genetically distinguishable from Pure bred Dogs of other Breeds, but the means by which kennel clubs classify Dogs is unsystematic.

Systematic analyses of the Dog Genome has revealed only Four Major Types of Dogs that can be said to be statistically distinct.

Four Major Types of Dogs according to Dog Genome:

Old World Dogs - Malamute, Shar Pei etc.
Mastiff Type - English Mastiff etc.
Herding Type - Border Collie etc.
Hunting Type - Hounds, Terriers etc. They are also known as Modern Types.

Some Breeds of Dog

Affenpinscher.
Bavarian Mountain Hound.
Beagle.
Canaan Dog.
Chihuahua.
Chow Chow.
Dutch Smoushond.
Elo.
Fila Brasileiro.

Scientific Classification

Kingdom - Animalia.
Phylum - Chordata.
Class - Mammalia.
Order - Carnivora.
Family - Canidae.
Genus - Canis.
Species - C. lupus.
Subspecies - C. l. familiaris.

Physical Features

Colour - Dogs come in a variety of Colours. Colour varies from White through Grays to Black and Browns from Light Tan to Dark Chocolate, in a wide variation of patterns. Domestic Dogs often display the remnants of counter shading, a common natural camouflage pattern. A counter shaded animal will have dark colouring on its upper surfaces and light colouring below, which reduces its general visibility. Thus many Breeds will have an occasional 'Blaze', 'Stripe' or 'Star' of White Fur on their Chest or Underside.

Weight - The Weight of a Dog varies form Breed to Breed. The Smallest Breed weighs about 113 grams (4.0 oz) and the Largest weights about 155.6 kilograms (343 lb).

Size - The Size of a Dog also varies form Breed to Breed. The Smallest Breed stands at only 6.3 centimetres (2.5 in) at the shoulder, 9.5 cm (3.7 in) in Length along the head-and-body. The Largest Breed is 250 cm (98 in) from the snout to the tail in Length and stands 106.7 cm (42.0 in) at the shoulder.

Dogs Hair is known as Coat. Coats can be short or long, coarse-haired to wool-like, straight, curly, or smooth. Most Dogs shed their coats seasonally. This is a natural occurrence that depends in large measure on the amount of available daylight. In the fall as days become shorter, a Dog’s coat will grow thicker and longer. In the spring the Dog will begin to shed its coat, and it will take longer for the coat to grow in over the summer.

The Coats of Domestic Dogs are of Two Varieties:

Double Coat - It is made up of a Coarse Guard Hair and is common in the Dogs found in Cold Climates.

Single Coat - It is made of Soft Down Hair and is found is common in the Dogs found in Hot Climates.

The Skeletal Frame of the Dog consists of 319 Bones. If a Dog’s tail is docked or absent at birth, there obviously are fewer bones in the skeleton. The muscles and tendons of a Dog are similar to those of a human; however, a Dog’s upper body muscles bear half the weight of the entire body and are better developed than a humans. The weight distribution between the front and the rear of the Dog are relatively equal.

Their legs are designed to propel them forward rapidly, leaping as necessary, to chase and overcome prey. Consequently, they have small, tight feet, walking on their toes; their rear legs are fairly rigid and sturdy; the front legs are loose and flexible, with only muscle attaching them to the torso.

Dogs have disconnected shoulder bones (lacking the collar bone of the human skeleton) that allow a greater stride length for running and leaping. They walk on four toes, front and back, and have Vestigial Dewclaws (dog thumbs) on their front legs and sometimes on their rear legs.When a Dog has extra dewclaws in addition to the usual one on each front leg, the Dog is said to be 'Double Dewclawed'.

Like most mammals, Dogs are Dichromats and have colour vision equivalent to red-green colour blindness in humans. Different breeds of Dogs have different eye shapes and dimensions, and they also have different retina configurations. Dogs with long noses have a "visual streak" which runs across the width of the retina and gives them a very wide field of excellent vision, while those with short noses have an 'Area Centralis' - a central patch with up to three times the density of nerve endings as the visual streak - giving them detailed sight much more like a humans. Some breeds, particularly the Sight Hounds, have a field of vision up to 270° (compared to 180° for humans), although broad-headed breeds with short noses have a much narrower field of vision, as low as 180°.

Dogs have nearly 220 million Smell-Sensitive Cells over an area about the size of a Pocket Handkerchief (compared to 5 million over an area the size of a postage stamp for humans).

Dogs have two sets of teeth. Twenty-Eight Deciduous Teeth erupt by six to eight weeks of age, and by the time puppies are six to seven months old these Deciduous Teeth are all replaced by 42 Adult Teeth. The Permanent Teeth include Incisors, which are used to nip and bite; Canines, which tear and shred flesh; and Premolars and Molars, which shear and crush. Therefore a Dog’s Teeth serve both as Weapons and as Tools for Cutting or Tearing food. The Canines are the Upper and Lower Fangs for which the Dog Family has earned the Name 'Canines'. The Teeth are High-Crowned and Pointed.

A Dog's Ears either Stick Up or Hang Down. The earliest Dogs probably had erect ears, but the ears began to droop in smaller, later breeds because of excessive ear skin. Dogs can detect sounds as low as the 16 to 20 Hz frequency range (compared to 20 to 70 Hz for humans) and above 45 kHz (compared to 13 to 20 kHz for humans), and in addition have a degree of Ear Mobility that helps them to rapidly pinpoint the exact location of a sound. Eighteen or more muscles can tilt, rotate and raise or lower a Dog's Ear. Additionally, a Dog can identify a sound's location much faster than a human can, as well as hear sounds up to four times the distance that humans are able to.

Head - There are two Basic Head Shapes:

1. Narrow Skull with a Long Face - Long-Faced Dogs, such as the German shepherd and the Cocker Spaniel, may have jaws eight inches long.

2. Wide Skull with a Short Face - The nose of Small-Faced Dogs, such as the Pekingese and the Pug, may be less than an inch from the eyes.

Tail - There are many different shapes for Dog tails: straight, straight up, sickle, curled, or cork-screw. In some breeds, the tail is traditionally docked to avoid injuries (especially for hunting dogs). In some breeds, puppies can be born with a short tail or no tail at all. This occurs more frequently in those Breeds that are frequently docked and thus have no breed standard regarding the tail.

All Dogs have 78 chromosomes, or 39 pairs of chromosomes (humans have 23 pairs), and one member of each pair comes from each parent. The normal temperature (rectal) of an Adult Dog is 100–102.5° F.

Geographical Range and Habitat

Domestic Dog is found all over the World in Homes, Villages, Cities, Farms etc. Mostly wherever there are Humans, Dogs can be found too.

Behaviour

Dogs are Territorial Animals. Dogs claim their territories based on the limitations of their owners. Dogs mark their territorial boundaries by Urinating and Rubbing their scent on the ground or on trees to warn other Animals of their presence. Sometimes these landmarks can be cars, fences, light post etc.

When on Neutral Ground, that which is not considered by either Dog, strangers greet each other and will go through formal rituals of sniffing, marking, tail wagging, and posturing. Unless they are claiming food or are engaged in courting the same Female, such interactions are usually terminated by each going its own way. But Females will attack strangers in neutral territory to protect their young ones.

Dogs communicate in several ways. They communicate through Scent, Body position, Movement and Facial Expressions. Many of these signals are easily recognizable even to humans, like the excited tail-wagging displays a happy Dog and the bared teeth display anger or threat. Vocally, Dogs communicate with a cacophony of sounds including barks, growls, and whines. Dogs, growl when cornered or are fearful. Some Breeds, such as the Siberian husky, howl rather than bark. While, the Basenji does not bark but rather emits a yodelling sound when it is happy.

Dog behaviour is affected by genetic factors as well as environmental factors. Puppies learn behaviours quickly by following examples set by experienced Dogs. This form of intelligence is not peculiar to those tasks Dogs have been bred to perform, but can be generalized to myriad abstract problems. For example, Dachshund puppies who watched an experienced Dog pull a cart by tugging on an attached piece of ribbon in order to get a reward from inside the cart learned the task fifteen times faster than those who were left to solve the problem on their own.

Dogs can also learn by mimicking human behaviours. In one study, puppies were presented with a box, and shown that when a handler pressed a lever, a ball would roll out of the box. The handler then allowed the puppy to play with the ball, making it an intrinsic reward. The pups were then allowed to interact with the box. Roughly three-quarters of the puppies subsequently touched the lever, and over half successfully released the ball, compared to only 6 percent in a control group that did not watch the human manipulate the lever. Another study found that handing an object between experimenters who then used the object's name in a sentence successfully taught an observing Dog each object's name, allowing the Dog to subsequently retrieve the item

The Teething process can be difficult for Puppies. Their gums hurt and become swollen, they may lose their appetites, and they may have mild intermittent diarrhoea.

Dogs rarely chew their food. Once the food is taken into the mouth, it is gulped or swallowed and passed through the oesophagus into the stomach, where digestive enzymes begin to break it down. Most of the digestion and absorption of food takes place in the small intestines with the aid of the pancreas and the liver. The pancreas secretes enzymes needed for regulating the digestive process

Many pet Dogs also bury bones or favourite toys for future use, just as their wild relatives sometimes bury a kill to secure the meat for later feasts.

Diet - Dogs are Omnivorous. Unlike an Obligate Carnivore, such as a member of the Cat family with its shorter small intestine, a Dog is neither dependent on meat-specific protein nor a very high level of protein in order to fulfil its basic dietary requirements. Dogs are able to healthily digest a variety of foods, including vegetables and grains, and can consume a large proportion of these in their diet.

Predators - Domestic Dogs do not have any Predators in the city, but in areas near the forest or where both Dogs and other large predators live, Dogs can be a major food source for big cats or canines. In Croatia Dogs are killed by Wolves more frequently than sheep. Wolves in Russia apparently limit feral Dog populations. Coyotes and Big Cats have also been known to attack Dogs. Leopards in particular are known to have a predilection for Dogs, and have been recorded to kill and consume them regardless of the Dog's size or ferocity. Tigers in Manchuria, Indochina, Indonesia, and Malaysia, are reputed to kill Dogs with the same vigour as leopards. Striped Hyenas are major predators of village Dogs in Turkmenistan, India, and the Caucasus. Reptiles such as Alligators and Pythons have also been known to kill and eat Dogs.

Reproduction

In domestic Dogs, sexual maturity begins to happen around age six to twelve months for both Males and Females, although this is delayed until up to two years old for some large breeds. This is the time at which Female Dogs will have their first estrous cycle. They will experience subsequent estrous cycles biannually, during which the body prepares for pregnancy. At the peak of the cycle, Females will come into oestrus, being mentally and physically receptive to copulation. Because the ova survive and are capable of being fertilized for a week after ovulation, it is possible for a female to mate with more than one male. Therefore Dogs are Polygamous. Dogs bear their litters roughly 56 to 72 days after fertilization, with an average of 63 days, although the length of gestation can vary. An average litter consists of about six puppies, though this number may vary widely based on the breed of Dog. Toy Dogs generally produce from one to four puppies in each litter, while much larger breeds may average as many as twelve. Some Dog breeds have acquired traits through selective breeding that interfere with reproduction. Male French Bulldogs, for instance, are incapable of mounting the Female. For many Dogs of this breed, the Female must be artificially inseminated in order to reproduce.

In Folklore and Culture

Dogs are famous for their Loyalty towards their owners. This quality has been depicted in a movie, titled 'Hachiko: A Dog's Story' released in 2009. The movie is based on Real Life of a Akita Dog named 'Hachiko' owned by 'Professor Hidesaburo Ueno'. The Professor lived in Tokyo and everyday Hachiko would see Ueno off to work from his home and then, at the end of the day, greet him at the nearby Shibuya Train Station. One day in May 1925 would be the end of their daily routine together, for Ueno suffered a fatal stroke during his day at work. He never returned to his faithful friend that day nor any day thereafter. Hachiko was given away to new owners but the loyal dog always ran off in search of his true master. After returning to Ueno's former home several times, Hachiko realized that he did not live there any more. Hachiko then searched for his friend at the train station. There he perpetually returned everyday henceforth, always at the end of the day and at the precise time of Ueno's scheduled arrival. Hachiko waited there in vain every day for 11 years. On March 8 1935, eleven years after it started, Hachiko's vigil came to an end. At almost 12 years old, the Akita succumbed to heart-worm disease.

Dogs find themselves in many of the Greek tales like the 'The Faithful Argus', 'The Dog who always catches its Prey' etc.

In Greek mythology, Canis Major (Great Dog) and Canis Minor (Little Dog) is The Great hunter, Orion's, two hunting Dogs. Canis Major is one of the most striking constellations in the heavens. Look for Sirius, 'The Dog Star', the brightest star in the heavens. Legend has it that Sirius is the diamond in Canis Major's collar.

In ancient Greece one of the most memorable mythological Dogs is Cerberus. Cerberus is the three-headed Dog who guards the gates of Hades. The three heads may represent the past, present and future, or birth, youth and old age. Cerberus allows people to enter Hades but doesn’t allow anyone to leave.

The Egyptians celebrated the rising of the Dog Star as the beginning of the year as it could coincide with the annual flooding and renewing of the Nile.

British mythology depicts the Dog as a faithful and loyal companion. It serves its master well and is prepared to defend that person to the death. King Arthur's faithful companion Cabal, is but one Dog that symbolises the relationship between humans and Dogs that has survived through the centuries.

It is suggested that Dogs can see spirits and apparitions while having the ability to sense that death is near. According to the myth, Dogs start howling when a person is about to die.

Dogs have been famously depicted in English literature, prominent amongst these are - 'The Hound of the Baskervilles', a crime novel by Sir Arthur Conan Doyle featuring the detective Sherlock Holmes and 'White Fang', a novel by American author Jack London.

The most famous Dog Cartoon is Walt Disney's 'Pluto' who is a pet of Mickey Mouse.

One of the most recent Animation movie based on a Dog, is 'Bolt' released in 2008.

Dogs are found throughout many Egyptian tombs. Most of the Dogs bear a resemblance to some of the Sight Hound breeds we still have today, such as the Ibizan Hound and the Saluki and the Greyhound - a breed that was probably known in Egypt in ancient times.

Dog meat is consumed in some East Asian countries, including Korea, China, and Vietnam, a practice that dates back to antiquity. It is estimated that 13–16 million Dogs are killed and consumed in Asia every year. In Korea, the primary Dog breed raised for meat is the Nureong.