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Domestic dog
Temporal range: 0.033–0Ma
Pleistocene – Recent
Nine different dog breeds
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Canidae
Genus: Canis
Species: C. lupus
Subspecies: C. l. familiaris
Trinomial name
Canis lupus familiaris[1]

The domestic dog (Canis lupus familiaris) is a canid that is known as man's best friend. The dog was the first domesticated animal[2][3] and has been widely kept as a working, hunting, and pet companion. According to recent coarse estimates, there are currently between 700 million and one billion dogs, making them the most abundant predators in the world.[4][5]


  • Etymology and related terminology 1
  • Taxonomy 2
  • Origin and evolution 3
  • Roles with humans 4
    • Early roles 4.1
    • As pets 4.2
    • Work 4.3
    • Sports and shows 4.4
    • As a food source 4.5
    • Health risks to humans 4.6
    • Health benefits for humans 4.7
    • Medical detection dogs 4.8
    • Shelters 4.9
  • Biology 5
    • Senses 5.1
      • Vision 5.1.1
      • Hearing 5.1.2
      • Smell 5.1.3
    • Physical characteristics 5.2
      • Coat 5.2.1
      • Tail 5.2.2
    • Types and breeds 5.3
    • Health 5.4
      • Mortality 5.4.1
      • Predation 5.4.2
    • Diet 5.5
      • Foods toxic to dogs 5.5.1
    • Reproduction 5.6
      • Neutering 5.6.1
    • Communication 5.7
  • Intelligence and behavior 6
    • Intelligence 6.1
    • Behavior 6.2
    • Dog growl 6.3
  • Differences from wolves 7
    • Physical characteristics 7.1
    • Behavioral differences 7.2
    • Trainability 7.3
  • Cultural depictions 8
    • Mythology 8.1
    • Gallery of dogs in art 8.2
  • See also 9
  • References 10
  • Bibliography 11
  • Further reading 12
  • External links 13

Etymology and related terminology

The term "domestic dog" is generally used for both of the domesticated and feral varieties. The English word dog comes from Middle English dogge, from Old English docga, a "powerful dog breed".[6] The term may possibly derive from Proto-Germanic *dukkōn, represented in Old English finger-docce ("finger-muscle").[7] The word also shows the familiar petname diminutive -ga also seen in frogga "frog", picga "pig", stagga "stag", wicga "beetle, worm", among others.[8] The term dog may ultimately derive from the earliest layer of Proto-Indo-European vocabulary, reflecting the role of the dog as the earliest domesticated animal.[9]

In 14th-century England, hound (from Old English: hund) was the general word for all domestic canines, and dog referred to a subtype of hound, a group including the mastiff. It is believed this "dog" type was so common, it eventually became the prototype of the category "hound".[10] By the 16th century, dog had become the general word, and hound had begun to refer only to types used for hunting.[11] Hound, cognate to German Hund, Dutch hond, common Scandinavian hund, and Icelandic hundur, is ultimately derived from the Proto-Indo-European *kwon- "dog", found in Sanskrit kukuur (कुक्कुर),[12] Welsh ci (plural cwn), Latin canis, Greek kýōn, and Lithuanian šuõ.[13]

In breeding circles, a male canine is referred to as a dog, while a female is called a bitch[14] (Middle English bicche, from Old English bicce, ultimately from Old Norse bikkja). A group of offspring is a litter. The father of a litter is called the sire, and the mother is called the dam. Offspring are, in general, called pups or puppies, from French poupée, until they are about a year old. The process of birth is whelping, from the Old English word hwelp (cf. German Welpe, Dutch welp, Swedish valpa, Icelandic hvelpur).[15] The term "whelp" can also be used to refer to the young of any canid, or as a (somewhat archaic) alternative to "puppy".

For other uses of the term dog see Dog.


In 1753, the father of modern biological taxonomy, Carl Linnaeus, listed among the types of quadrupeds familiar to him, the Latin word for dog, canis. Among the species within this genus, Linnaeus listed the fox, as Canis vulpes, wolves (Canis lupus), and the domestic dog, (Canis canis). In later editions, Linnaeus dropped Canis canis and greatly expanded his list of the Canis genus of quadrupeds, and by 1758 included alongside the foxes, wolves, and jackals and many more terms that are now listed as synonyms for domestic dog, including aegyptius (hairless dog), aquaticus, (water dog), and mustelinus (literally "badger dog"). Among these were two that later experts have been widely used for domestic dogs as a species: Canis domesticus and, most predominantly, Canis familiaris, the "common" or "familiar" dog.[16]

By 1993 with advancements in molecular biology, the mitochondrial DNA mtDNA analysis of extant (i.e. living today) Canidea species indicated that "The domestic dog is an extremely close relative of the gray wolf, differing from it by at most 0.2% of mtDNA sequence.... In comparison, the gray wolf differs from its closest wild relative, the coyote, by about 4% of mitochondrial DNA sequence."[17] In the same year, the domestic dog Canis familiaris was reclassified as Canis lupus familiaris, a subspecies of the gray wolf Canis lupus in Mammal Species of the World.[18] In 1995, research indicated that the wolf may have been the ancestor of the dog.[19] By 1999, further genetic analysis indicated that the domestic dog may have emerged from multiple wolf populations.[20][21] Based on these latest two pieces of research and the reference reclassification, canis lupis familiaris is the name for the taxon listed by ITIS.[22] However, canis familiaris is also accepted due to a nomenclature debate regarding the naming of wild and domestic sub-species.[23]

Origin and evolution

For the origin, domestication, DNA evidence and archeological evidence for the dog, see Origin of the domestic dog

The dog began from a single domestication of a now-extinct wolf-like canid in Western Europe 11 to 16 thousand years ago. This period predates the rise of agriculture and implies that the earliest dogs arose along with hunter-gatherers and not agriculturists.[24] Conceivably, proto-dogs might have taken advantage of carcasses left on site by early hunters, assisted in the capture of prey, or provided defense from large competing predators at kills. Furthermore, several ancient dogs may represent failed domestication events, such as the 36,000 year old Goyet specimen of Belgium and the 33,000 year old Altai Mountains specimen from Russia, as they have no descendents today.[25][26] This era towards the end of the last ice age is known as the Magdalenian period dating from around 17,000 to 12,000 years ago,[27] and refers to one of the later cultures of the Upper Paleolithic in western Europe at that time.

"We know also that there were distinct wolf populations existing ten of thousands of years ago. One such wolf, which we call the megafaunal wolf, preyed on large game such as horses, bison and perhaps very young mammoths. Isotope data show that they ate these species, and the dog may have been derived from a wolf similar to these ancient wolves in the late Pleistocene of Europe." [28]

Roles with humans

Domestic dogs inherited complex behaviors, such as bite inhibition, from their wolf ancestors, which would have been pack hunters with complex body language. These sophisticated forms of social cognition and communication may account for their trainability, playfulness, and ability to fit into human households and social situations, and these attributes have given dogs a relationship with humans that has enabled them to become one of the most successful species on the planet today.[29]:pages95-136

The dogs' value to early human hunter-gatherers led to them quickly becoming ubiquitous across world cultures. Dogs perform many roles for people, such as hunting, herding, pulling loads, protection, assisting police and military, companionship, and, more recently, aiding handicapped individuals. This impact on human society has given them the nickname "man's best friend" in the Western world. In some cultures, however, dogs are also a source of meat.[30][31]

Early roles

Wolves, and their dog descendants, would have derived significant benefits from living in human camps—more safety, more reliable food, lesser caloric needs, and more chance to breed.[32] They would have benefited from humans' upright gait that gives them larger range over which to see potential predators and prey, as well as color vision that, at least by day, gives humans better visual discrimination.[32] Camp dogs would also have benefitted from human tool use, as in bringing down larger prey and controlling fire for a range of purposes.[32]

Humans would also have derived enormous benefit from the dogs associated with their camps.[33] For instance, dogs would have improved sanitation by cleaning up food scraps.[33] Dogs may have provided warmth, as referred to in the Australian Aboriginal expression "three dog night" (an exceptionally cold night), and they would have alerted the camp to the presence of predators or strangers, using their acute hearing to provide an early warning.[33]

Anthropologists believe the most significant benefit would have been the use of dogs' sensitive sense of smell to assist with the hunt.[33] The relationship between the presence of a dog and success in the hunt is often mentioned as a primary reason for the domestication of the wolf, and a 2004 study of hunter groups with and without a dog gives quantitative support to the hypothesis that the benefits of cooperative hunting was an important factor in wolf domestication.[34]

The cohabitation of dogs and humans would have greatly improved the chances of survival for early human groups, and the domestication of dogs may have been one of the key forces that led to human success.[35]

Emigrants from Siberia likely crossed the Bering Strait with dogs in their company, and some experts[36] suggest the use of sled dogs may have been critical to the success of the waves that entered North America roughly 12,000 years ago,[36] although the earliest archaeological evidence of dog-like canids in North America dates from about 9,400 years ago.[37][29]:104 Dogs were an important part of life for the Athabascan population in North America, and were their only domesticated animal. Dogs also carried much of the load in the migration of the Apache and Navajo tribes 1,400 years ago. Use of dogs as pack animals in these cultures often persisted after the introduction of the horse to North America.[38]

As pets

Couple sitting on the lawn with a pet British Bulldog
A British Bulldog shares a day at the park.

A young male border terrier with a raccoon toy.

"The most widespread form of interspecies bonding occurs between humans and dogs"[33] and the keeping of dogs as companions, particularly by elites, has a long history.[39] (As a possible example, at the Natufian culture site of Ain Mallaha in Israel, dated to 12,000 BC, the remains of an elderly human and a four-to-five-month-old puppy were found buried together).[19] However, pet dog populations grew significantly after World War II as suburbanization increased.[39] In the 1950s and 1960s, dogs were kept outside more often than they tend to be today[40] (using the expression "in the doghouse" to describe exclusion from the group signifies the distance between the doghouse and the home) and were still primarily functional, acting as a guard, children's playmate, or walking companion. From the 1980s, there have been changes in the role of the pet dog, such as the increased role of dogs in the emotional support of their human guardians.[41] People and dogs have become increasingly integrated and implicated in each other's lives,[42] to the point where pet dogs actively shape the way a family and home are experienced.[43]

There have been two major trends in the changing status of pet dogs. The first has been the 'commodification' of the dog, shaping it to conform to human expectations of personality and behaviour.[43] The second has been the broadening of the concept of the family and the home to include dogs-as-dogs within everyday routines and practices.[43]

There are a vast range of commodity forms available to transform a pet dog into an ideal companion.[44] The list of goods, services and places available is enormous: from dog perfumes, couture, furniture and housing, to dog groomers, therapists, trainers and caretakers, dog cafes, spas, parks and beaches, and dog hotels, airlines and cemeteries.[44] While dog behaviors such as barking, jumping up, digging, rolling in dung, fighting, and urine marking became increasingly incompatible with the new role of a pet dog.[45] Dog training books, classes and television programs proliferated as the process of commodifying the pet dog continued.[46]

An Australian Cattle Dog in reindeer antlers sits on Santa's lap
A pet dog taking part in Christmas traditions

The majority of contemporary people with dogs describe their pet as part of the family,[43] although some ambivalence about the relationship is evident in the popular reconceptualization of the dog–human family as a pack.[43] A dominance model of dog–human relationships has been promoted by some dog trainers, such as on the television program Dog Whisperer. However it has been disputed that "trying to achieve status" is characteristic of dog–human interactions.[47] Pet dogs play an active role in family life; for example, a study of conversations in dog–human families showed how family members use the dog as a resource, talking to the dog, or talking through the dog, to mediate their interactions with each other.[48]

Another study of dogs' roles in families showed many dogs have set tasks or routines undertaken as family members, the most common of which was helping with the washing-up by licking the plates in the dishwasher, and bringing in the newspaper from the lawn.[43] Increasingly, human family members are engaging in activities centered on the perceived needs and interests of the dog, or in which the dog is an integral partner, such as Dog Dancing and Doga.[44]

According to statistics published by the American Pet Products Manufacturers Association in the National Pet Owner Survey in 2009–2010, it is estimated there are 77.5 million people with pet dogs in the United States.[49] The same survey shows nearly 40% of American households own at least one dog, of which 67% own just one dog, 25% two dogs and nearly 9% more than two dogs. There does not seem to be any gender preference among dogs as pets, as the statistical data reveal an equal number of female and male dog pets. Yet, although several programs are undergoing to promote pet adoption, less than a fifth of the owned dogs come from a shelter.

The latest study using Magnetic resonance imaging (MRI) to humans and dogs together proved that dogs have same response to voices and use the same parts of the brain as humans to do so. This gives dogs the ability to recognize emotional human sounds, making them friendly social pets to humans.[50]


Dogs have lived and worked with humans in so many roles that they have earned the unique nickname, "man's best friend",[51] a phrase used in other languages as well. They have been bred for herding livestock,[52] hunting (e.g. pointers and hounds),[53] rodent control,[54] guarding, helping fishermen with nets, detection dogs, and pulling loads, in addition to their roles as companions.[54] In 1957, a husky-terrier mix named Laika became the first animal to orbit the Earth.[55][56]

Book of the Hunt, Gaston III, Count of Foix, 1387–88.

Service dogs such as guide dogs, utility dogs, assistance dogs, hearing dogs, and psychological therapy dogs provide assistance to individuals with physical or mental disabilities.[57][58] Some dogs owned by epileptics have been shown to alert their handler when the handler shows signs of an impending seizure, sometimes well in advance of onset, allowing the guardian to seek safety, medication, or medical care.[59]

Dogs included in human activities in terms of helping out humans are usually called working dogs. Dogs of several breeds are considered working dogs. Some working dog breeds include Akita, Alaskan Malamute, Anatolian Shepherd Dog, Bernese Mountain Dog, Black Russian Terrier, Boxer, Bullmastiff, Doberman Pinscher, Dogue de Bordeaux, German Pinscher, German Shepherd,[60] Giant Schnauzer, Great Dane, Great Pyrenees, Great Swiss Mountain Dog, Komondor, Kuvasz, Mastiff, Neapolitan Mastiff, Newfoundland, Portuguese Water Dog, Rottweiler, Saint Bernard, Samoyed, Siberian Husky, Standard Schnauzer, and Tibetan Mastiff.

Sports and shows

People often enter their dogs in competitions[61] such as breed-conformation shows or sports, including racing, sledding and agility competitions.

In conformation shows, also referred to as breed shows, a judge familiar with the specific dog breed evaluates individual purebred dogs for conformity with their established breed type as described in the breed standard. As the breed standard only deals with the externally observable qualities of the dog (such as appearance, movement, and temperament), separately tested qualities (such as ability or health) are not part of the judging in conformation shows.

As a food source

Gaegogi (dog meat) stew being served in a Korean restaurant

Dog meat is consumed in some East Asian countries, including Korea, China, and Vietnam, a practice that dates back to antiquity.[62] It is estimated that 13–16 million dogs are killed and consumed in Asia every year.[63] The BBC claims that, in 1999, more than 6,000 restaurants served soups made from dog meat in South Korea.[64] In Korea, the primary dog breed raised for meat, the nureongi (누렁이), differs from those breeds raised for pets that Koreans may keep in their homes.[65]

The most popular Korean dog dish is gaejang-guk (also called bosintang), a spicy stew meant to balance the body's heat during the summer months; followers of the custom claim this is done to ensure good health by balancing one's gi, or vital energy of the body. A 19th century version of gaejang-guk explains that the dish is prepared by boiling dog meat with scallions and chili powder. Variations of the dish contain chicken and bamboo shoots. While the dishes are still popular in Korea with a segment of the population, dog is not as widely consumed as beef, chicken, and pork.[65]

A CNN report in China dated March 2010 includes an interview with a dog meat vendor who stated that most of the dogs that are available for selling to restaurants are raised in special farms but that there is always a chance that a sold dog is someone's lost pet, although dog pet breeds are not considered edible.[66]

Other cultures, such as Polynesia and pre-Columbian Mexico, also consumed dog meat in their history. However, Western, South Asian, African, and Middle Eastern cultures, in general, regard consumption of dog meat as taboo. In some places, however, such as in rural areas of Poland, dog fat is believed to have medicinal properties—being good for the lungs for instance.[67] Dog meat is also consumed in some parts of Switzerland.[68]

Health risks to humans

Pet waste station at a government building.

It is estimated that 4.7 million people are bitten by dogs each year.[69] In the 1980s and 1990s the US averaged 17 fatalities per year, while in the 2000s this has increased to 26.[70] 77% of dog bites are from the pet of family or friends, and 50% of attacks occur on the property of the dog's legal owner.[70]

A Colorado study found bites in children were less severe than bites in adults.[71] The incidence of dog bites in the US is 12.9 per 10,000 inhabitants, but for boys aged 5 to 9, the incidence rate is 60.7 per 10,000. Moreover, children have a much higher chance to be bitten in the face or neck.[72] Sharp claws with powerful muscles behind them can lacerate flesh in a scratch that can lead to serious infections.[73]

In the UK between 2003 and 2004, there were 5,868 dog attacks on humans, resulting in 5,770 working days lost in sick leave.[74]

In the United States, cats and dogs are a factor in more than 86,000 falls each year.[75] It has been estimated around 2% of dog-related injuries treated in UK hospitals are domestic accidents. The same study found that while dog involvement in road traffic accidents was difficult to quantify, dog-associated road accidents involving injury more commonly involved two-wheeled vehicles.[76]

Toxocara canis (dog roundworm) eggs in dog feces can cause toxocariasis. In the United States, about 10,000 cases of Toxocara infection are reported in humans each year, and almost 14% of the U.S. population is infected.[77] In Great Britain, 24% of soil samples taken from public parks contained T. canis eggs.[78] Untreated toxocariasis can cause retinal damage and decreased vision.[78] Dog feces can also contain hookworms that cause cutaneous larva migrans in humans.[79][80][81][82]

Health benefits for humans

Small dog laying between the hands
A human cuddles a Doberman puppy.

The scientific evidence is mixed as to whether companionship of a dog can enhance human physical health and psychological wellbeing.[83] Studies suggesting that there are benefits to physical health and psychological wellbeing[84] have been criticised for being poorly controlled,[85] and finding that "[t]he health of elderly people is related to their health habits and social supports but not to their ownership of, or attachment to, a companion animal." Earlier studies have shown that people who keep pet dogs or cats exhibit better mental and physical health than those who do not, making fewer visits to the doctor and being less likely to be on medication than non-guardians.[86]

A 2005 paper states "recent research has failed to support earlier findings that pet ownership is associated with a reduced risk of cardiovascular disease, a reduced use of general practitioner services, or any psychological or physical benefits on health for community dwelling older people. Research has, however, pointed to significantly less absenteeism from school through sickness among children who live with pets."[83] In one study, new guardians reported a highly significant reduction in minor health problems during the first month following pet acquisition, and this effect was sustained in those with dogs through to the end of the study.[87]

In addition, people with pet dogs took considerably more physical exercise than those with cats and those without pets. The group without pets exhibited no statistically significant changes in health or behaviour. The results provide evidence that keeping pets may have positive effects on human health and behaviour, and that for guardians of dogs these effects are relatively long-term.[87] Pet guardianship has also been associated with increased coronary artery disease survival, with human guardians being significantly less likely to die within one year of an acute myocardial infarction than those who did not own dogs.[88]

Gunnar Kaasen and Balto, the lead dog on the last relay team of the 1925 serum run to Nome.

The health benefits of dogs can result from contact with dogs in general, and not solely from having dogs as pets. For example, when in the presence of a pet dog, people show reductions in cardiovascular, behavioral, and psychological indicators of anxiety.[89] Other health benefits are gained from exposure to immune-stimulating microorganisms, which, according to the hygiene hypothesis, can protect against allergies and autoimmune diseases. The benefits of contact with a dog also include social support, as dogs are able to not only provide companionship and social support themselves, but also to act as facilitators of social interactions between humans.[90] One study indicated that wheelchair users experience more positive social interactions with strangers when they are accompanied by a dog than when they are not.[91]

The practice of using dogs and other animals as a part of therapy dates back to the late 18th century, when animals were introduced into mental institutions to help socialize patients with mental disorders.[92] Animal-assisted intervention research has shown that animal-assisted therapy with a dog can increase social behaviors, such as smiling and laughing, among people with Alzheimer's disease.[93] One study demonstrated that children with ADHD and conduct disorders who participated in an education program with dogs and other animals showed increased attendance, increased knowledge and skill objectives, and decreased antisocial and violent behavior compared to those who were not in an animal-assisted program.[94]

Medical detection dogs

Medical detection dogs are early warning of diseases by sniffing of its nose to human directly or its urine or speciment. Dog can detect oudors in one part per trillion, because dog has brain which can detect oudor 40 times powerful than human has. Dog has 300 million oudor receptors in its nose, while human has only 5 million. Every dog has training specifically for detection one kind of disease from blood glucose level of diabetic to cancer. To train a cancer dog need 6 months. A Labrador Retriever is called Daisy has detect 551 cancer patients with accuracy 93 percent and got Blue Cross (for pets) Medal for her life-saving skills.[95][96]


Every year, between 6 and 8 million dogs and cats enter US animal shelters.[97] The Humane Society of the United States (HSUS) estimates that approximately 3 to 4 million of those dogs and cats are euthanized yearly in the United States.[98] However, the percentage of dogs in US animal shelters that are eventually adopted and removed from the shelters by their new legal owners has increased since the mid-1990s from around 25% to a 2012 average of 40% among reporting shelters[99] (and many shelters reporting 60–75%).[100]


Lateral view of a dog's bone structure.

Domestic dogs have been selectively bred for millennia for various behaviors, sensory capabilities, and physical attributes.[54] Modern dog breeds show more variation in size, appearance, and behavior than any other domestic animal. Nevertheless, their morphology is based on that of their wild wolf ancestors.[54] Dogs are predators and scavengers, and like many other predatory mammals, the dog has powerful muscles, fused wrist bones, a cardiovascular system that supports both sprinting and endurance, and teeth for catching and tearing.

Dogs are highly variable in height and weight. The smallest known adult dog was a Yorkshire Terrier, that stood only 6.3 cm (2.5 in) at the shoulder, 9.5 cm (3.7 in) in length along the head-and-body, and weighed only 113 grams (4.0 oz). The largest known dog was an English Mastiff which weighed 155.6 kg (343 lb) and was 250 cm (98 in) from the snout to the tail.[101] The tallest dog is a Great Dane that stands 106.7 cm (42.0 in) at the shoulder.[102]



Dog's visual colour perception compared with humans.

Like most mammals, dogs are dichromats and have color vision equivalent to red–green color blindness in humans (deuteranopia).[103][104][105][106] So, dogs can see blue and yellow, but have difficulty differentiating red and green because they only have two spectral types of cone photoreceptor, while normal humans have three. And dogs use color instead of brightness to differentiate light or dark blue/yellow.[107][108][109][110] Dogs are less sensitive to differences in grey shades than humans and also can detect brightness at about half the accuracy of humans.[111]

The dog's visual system has evolved to aid proficient hunting.[103] While a dog's visual acuity is poor (that of a poodle's has been estimated to translate to a Snellen rating of 20/75[103]), their visual discrimination for moving objects is very high; dogs have been shown to be able to discriminate between humans (e.g., identifying their human guardian) at a range of between 800 and 900 m, however this range decreases to 500–600 m if the object is stationary.[103]

Dogs have a temporal resolution of between 60 and 70 Hz, which explains why many dogs struggle to watch television, as most such modern screens are optimized for humans at 50–60 Hz.[111] Dogs can detect a change in movement that exists in a single diopter of space within their eye. Humans, by comparison, require a change of between 10 and 20 diopters to detect movement.[112]

As crepuscular hunters, dogs often rely on their vision in low light situations: They have very large pupils, a high density of rods in the fovea, an increased flicker rate, and a tapetum lucidum.[103] The tapetum is a reflective surface behind the retina that reflects light to give the photoreceptors a second chance to catch the photons. There is also a relationship between body size and overall diameter of the eye. A range of 9.5 and 11.6 mm can be found between various breeds of dogs. This 20% variance can be substantial and is associated as an adaptation toward superior night vision.[113]

The eyes of different breeds of dogs have different shapes, dimensions, and retina configurations.[114] Many long-nosed breeds have a "visual streak"—a wide foveal region that runs across the width of the retina and gives them a very wide field of excellent vision. Some long-muzzled breeds, in particular, the sighthounds, have a field of vision up to 270° (compared to 180° for humans). Short-nosed breeds, on the other hand, 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 human's. Some broad-headed breeds with short noses have a field of vision similar to that of humans.[104][105]

Most breeds have good vision, but some show a genetic predisposition for myopia – such as Rottweilers, with which one out of every two has been found to be myopic.[103] Dogs also have a greater divergence of the eye axis than humans, enabling them to rotate their pupils farther in any direction. The divergence of the eye axis of dogs ranges from 12–25° depending on the breed.[112]

Experimentation has proven that dogs can distinguish between complex visual images such as that of a cube or a prism. Dogs also show attraction to static visual images such as the silhouette of a dog on a screen, their own reflections, or videos of dogs; however, their interest declines sharply once they are unable to make social contact with the image.[115]


The physiology of a dog ear.
Transformation of the ears of a huskamute puppy in 6 days

The frequency range of dog hearing is approximately 40 Hz to 60,000 Hz,[116] which means that dogs can detect sounds far beyond the upper limit of the human auditory spectrum.[105][116][117] In addition, dogs have ear mobility, which allows them to rapidly pinpoint the exact location of a sound.[118] Eighteen or more muscles can tilt, rotate, raise, or lower a dog's ear. A dog can identify a sound's location much faster than a human can, as well as hear sounds at four times the distance.[118]


The wet, textured nose of a dog

While the human brain is dominated by a large visual cortex, the dog brain is dominated by an olfactory cortex.[103] The olfactory bulb in dogs is roughly forty times bigger than the olfactory bulb in humans, relative to total brain size, with 125 to 220 million smell-sensitive receptors.[103] The bloodhound exceeds this standard with nearly 300 million receptors.[103]

Consequently, it has been estimated that dogs, in general, have an olfactory sense ranging from one hundred thousand to one million times more sensitive than a human's. In some dog breeds, such as bloodhounds, the olfactory sense may be up to 100 million times greater than a human's.[119] The wet nose, or rhinarium, is essential for determining the direction of the air current containing the smell. Cold receptors in the skin are sensitive to the cooling of the skin by evaporation of the moisture by air currents.[120]

Physical characteristics


A heavy winter coat with countershading in a mixed-breed dog

The coats of domestic dogs are of two varieties: "double" being common with dogs (as well as wolves) originating from colder climates, made up of a coarse guard hair and a soft down hair, or "single", with the topcoat only.

Domestic dogs often display the remnants of countershading, a common natural camouflage pattern. A countershaded animal will have dark coloring on its upper surfaces and light coloring below,[121] which reduces its general visibility. Thus, many breeds will have an occasional "blaze", stripe, or "star" of white fur on their chest or underside.[122]


There are many different shapes for dog tails: straight, straight up, sickle, curled, or cork-screw. As with many canids, one of the primary functions of a dog's tail is to communicate their emotional state, which can be important in getting along with others. In some hunting dogs, however, the tail is traditionally docked to avoid injuries.[123] In some breeds, such as the Braque du Bourbonnais, puppies can be born with a short tail or no tail at all.[124]

Types and breeds

Cavalier King Charles Spaniels demonstrate within-breed variation.

Most breeds of dog are at most a few hundred years old, having been artificially selected for particular morphologies and behaviors by people for specific functional roles. Through this selective breeding, the dog has developed into hundreds of varied breeds, and shows more behavioral and morphological variation than any other land mammal.[125] For example, height measured to the withers ranges from 15.2 centimetres (6.0 in) in the Chihuahua to about 76 cm (30 in) in the Irish Wolfhound; color varies from white through grays (usually called "blue") to black, and browns from light (tan) to dark ("red" or "chocolate") in a wide variation of patterns; coats can be short or long, coarse-haired to wool-like, straight, curly, or smooth.[126] It is common for most breeds to shed this coat.

While all dogs are genetically very similar,[127] natural selection and selective breeding have reinforced certain characteristics in certain populations of dogs, giving rise to dog types and dog breeds. Dog types are broad categories based on function, genetics, or characteristics.[128] Dog breeds 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.

Purebred dogs of one breed are genetically distinguishable from purebred dogs of other breeds,[129] 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.[129] These include the "old world dogs" (e.g., Malamute and Shar Pei), "Mastiff"-type (e.g., English Mastiff), "herding"-type (e.g., Border Collie), and "all others" (also called "modern"- or "hunting"-type).[129][130]


Dogs are susceptible to various diseases, ailments, and poisons, some of which can affect humans. To defend against many common diseases, dogs are often vaccinated.

There are many household plants that are poisonous to dogs, begonia and aloe vera.[131] Poinsettia is often claimed to be toxic but this is untrue. The LD50 for rats was determined to be greater than 25g/kg.[132] This would mean that a 50 pound dog would have to eat 500-600 leaves to have a 50% chance of death.

Some breeds of dogs are prone to certain genetic ailments such as elbow or hip dysplasia, blindness, deafness, pulmonic stenosis, cleft palate, and trick knees. Two serious medical conditions particularly affecting dogs are pyometra, affecting unspayed females of all types and ages, and bloat, which affects the larger breeds or deep-chested dogs. Both of these are acute conditions, and can kill rapidly. Dogs are also susceptible to parasites such as fleas, ticks, and mites, as well as hookworm, tapeworm, roundworm, and heartworm.

Dogs are highly susceptible to theobromine poisoning, typically from ingestion of chocolate. Theobromine is toxic to dogs because, although the dog's metabolism is capable of breaking down the chemical, the process is so slow that even small amounts of chocolate can be fatal, especially dark chocolate.

Dogs are also vulnerable to some of the same health conditions as humans, including diabetes, dental and heart disease, epilepsy, cancer, hypothyroidism, and arthritis.[133]


A mixed-breed terrier. Mixed-breed dogs are generally healthier than pure-breds.

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.[134][135][136][137] Individual dogs may live well beyond the median of their breed.

The breed with the shortest lifespan (among breeds for which there is a questionnaire survey with a reasonable sample size) is the Dogue de Bordeaux, with a median longevity of about 5.2 years, but several breeds, including Miniature Bull Terriers, Bloodhounds, and Irish Wolfhounds are nearly as short-lived, with median longevities of 6 to 7 years.[137]

The longest-lived breeds, including Toy Poodles, Japanese Spitz, Border Terriers, and Tibetan Spaniels, have median longevities of 14 to 15 years.[137] The median longevity of mixed-breed dogs, taken as an average of all sizes, is one or more years longer than that of purebred dogs when all breeds are averaged.[135][136][137][138] The dog widely reported to be the longest-lived is "Bluey", who died in 1939 and was claimed to be 29.5 years old at the time of his death; however, the Bluey record is anecdotal and unverified.[139] On 5 December 2011, Pusuke, the world's oldest living dog recognized by Guinness Book of World Records, died aged 26 years and 9 months.[140]


Although wild dogs, like wolves, are apex predators, they can be killed in territory disputes with wild animals.[141] Furthermore, in areas where both dogs and other large predators live, dogs can be a major food source for big cats or canines. Reports from Croatia indicate wolves kill dogs more frequently than they kill sheep. Wolves in Russia apparently limit feral dog populations. In Wisconsin, more compensation has been paid for dog losses than livestock.[141] Some wolf pairs have been reported to prey on dogs by having one wolf lure the dog out into heavy brush where the second animal waits in ambush.[142] In some instances, wolves have displayed an uncharacteristic fearlessness of humans and buildings when attacking dogs, to the extent that they have to be beaten off or killed.[143]

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.[144] Tigers in Manchuria, Indochina, Indonesia, and Malaysia are reputed to kill dogs with the same vigor as leopards.[145] Striped Hyenas are major predators of village dogs in Turkmenistan, India, and the Caucasus.[146] Reptiles such as alligators and pythons have been known to kill and eat dogs.


Golden Retriever gnawing a pig's foot

Despite their descent from wolves and classification as Carnivora, dogs are variously described in scholarly and other writings as carnivores[147][148] or omnivores.[54][149][150][151] Unlike obligate carnivores, such as the cat family with its shorter small intestine, dogs can adapt to a wide-ranging diet, and are not dependent on meat-specific protein nor a very high level of protein in order to fulfill their basic dietary requirements. Dogs will healthily digest a variety of foods, including vegetables and grains, and can consume a large proportion of these in their diet.[54] Compared to their wolf ancestors, dogs have adaptations in genes involved in starch digestion that contribute to an increased ability to thrive on a starch-rich diet.[152]

Foods toxic to dogs

A number of common human foods and household ingestibles are toxic to dogs, including chocolate solids (theobromine poisoning), onion and garlic (thiosulphate, sulfoxide or disulfide poisoning),[153] grapes and raisins, macadamia nuts, xylitol,[154] as well as various plants and other potentially ingested materials.[155][156] The nicotine in tobacco can also be dangerous. Dogs can get it by scavenging in garbage or ashtrays; eating cigars and cigarettes. Signs can be vomiting of large amounts (e.g., from eating cigar butts) or diarrhea. Some other signs are abdominal pain, loss of coordination, collapse, or death. To solve, soothe the stomach irritation by giving charcoal tablets. For severe signs, get immediate veterinary attention.[157]


In domestic dogs, sexual maturity begins to happen around age six to twelve months for both males and females,[54][158] although this can be 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 estrus, being mentally and physically receptive to copulation.[54] 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.[54]

2–5 days post conception fertilization occurs, 14–16 days embryo attaches to uterus 22–23 days heart beat is detectable.[159][160]

Dogs bear their litters roughly 58 to 68 days after fertilization,[54][161] with an average of 63 days, although the length of gestation can vary. An average litter consists of about six puppies,[162] though this number may vary widely based on the breed of dog. In general, toy dogs 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.[163]


A feral dog from Sri Lanka nursing her four puppies

Neutering refers to the sterilization of animals, usually by removal of the male's testicles or the female's ovaries and uterus, in order to eliminate the ability to procreate and reduce sex drive. Because of the overpopulation of dogs in some countries, many animal control agencies, such as the American Society for the Prevention of Cruelty to Animals (ASPCA), advise that dogs not intended for further breeding should be neutered, so that they do not have undesired puppies that may have to later be euthanized.[164]

According to the animal protection organizations urge people to neuter their pets and to adopt animals from shelters instead of purchasing them.

Neutering reduces problems caused by

  • Biodiversity Heritage Library bibliography for Canis lupus familiaris
  • Fédération Cynologique Internationale (FCI) – World Canine Organisation
  • Dogs in the Ancient World, an article on the history of dogs
  • View the dog genome on Ensembl

External links

  • De Vito, Dominique (September 1, 2005). World Atlas of Dog Breeds (Print) (6th ed.). Neptune City, NJ Lanham, MD: TFH Publications, Inc. pp. 960 pages.  
  • Wilcox, Bonnie; Walkowicz, Chris (March 1995). Atlas of Dog Breeds of the World (Print) (5th ed.). Neptune City, NJ Lanham, MD: TFH Publications, Inc. Distributed in the U.S. to the Bookstore and library trade by National Book Network. p. 912.  

Further reading

  • Miklósi, Adám (2007). Dog Behaviour, Evolution, and Cognition. Oxford University Press.  


  1. ^ "Mammal Species of the World – Browse: Canis lupus familiaris". 2005. Retrieved 12 March 2012. 
  2. ^ Nikolai D. Ovodov, Susan J. Crockford, Yaroslav V. Kuzmin, Thomas F. G. Higham, Gregory W. L. Hodgins, Johannes van der Plicht. (2011). A 33,000-Year-Old Incipient Dog from the Altai Mountains of Siberia: Evidence of the Earliest Domestication Disrupted by the Last Glacial Maximum. Published: 28 July, 2011DOI: 10.1371/journal.pone.0022821. Page 1 online here OCT14
  3. ^ Greger Larson, Elinor K. Karlsson, Angela Perri, Matthew T. Webster, Simon Y. W. Ho, Joris Peters, Peter W. Stahl, Philip J. Piper, Frode Lingaas, Merete Fredholm, Kenine E. Comstock, Jaime F. Modiano, Claude Schelling, Alexander I. Agoulnik, Peter A. Leegwater, Keith Dobney, Jean-Denis Vignes, Carles Vilàt, Leif Anderssond, and Kerstin Lindblad-Toh; Edited by Joachim Burger. (2012). Rethinking dog domestication by integrating genetics, archeology, and biogeography. vol. 109 no. 23 > Greger Larson, 8878–8883, doi: 10.1073/pnas.1203005109. Page 1 online here OCT14
  4. ^ Hughes, Joelene; Macdonald, David W. (2013). "A review of the interactions between free-roaming domestic dogs and wildlife". Biological Conservation 157: 341–351.  
  5. ^ Gompper, Matthew E. (2013). "The dog–human–wildlife interface: assessing the scope of the problem". In Gompper, Matthew E. Free-Ranging Dogs and Wildlife Conservation. Oxfort University Press. pp. 9–54. 
  6. ^ "Domestic PetDog Classified By Linnaeus In 1758 As Canis Familiaris And Canis Familiarus Domesticus". Retrieved 18 June 2008. 
  7. ^ Seebold, Elmar (2002). Kluge. Etymologisches Wörterbuch der deutschen Sprache. Berlin/New York:  
  8. ^ "Dictionary of Etymology",, s.v. dog, retrieved on 27 May 2009.
  9. ^ Mallory, J. R. (1991). In search of the Indo-Europeans: language, archaeology and myth. London: Thames and Hudson.  
  10. ^ Broz, Vlatko (2008). "Diachronic Investigations of False Friends". Contemporary Linguistics (Suvremena lingvistika) 66 (2): 199–222. 
  11. ^ René Dirven; Marjolyn Verspoor (2004). Cognitive exploration of language and linguistics. John Benjamins Publishing Company. pp. 215–216.  
  12. ^ Sanskrit Dictionary for Spoken Sanskrit
  13. ^ "The American Heritage Dictionary of the English Language: Fourth Edition". Archived from the original on 18 October 2006. Retrieved 30 November 2006. 
  14. ^ "Dog".  
  15. ^ Gould, Jean (1978). All about dog breeding for quality and soundness. London, Eng: Pelham.  
  16. ^  
  17. ^ Wayne, Robert K. (1993). "Molecular evolution of the dog family". Trends in Genetics 9 (6): 218–224.  
  18. ^ Wozencraft, W.C. (1993), Wilson and Reeder, ed., Animal Species of the World:A Taxonomic and Geographic Reference, 2nd edition, Washington, D.C.: Smithsonian Institution Press,  
  19. ^ a b Clutton-Brock, Juliet (1995), "Origins of the dog: domestication and early history", in Serpell, James, The domestic dog: its evolution, behaviour and interactions with people, Cambridge: Cambridge University Press,  
  20. ^ Wayne, Robert K.; Ostrander, Elaine A. (1999). "Origin, genetic diversity, and genome structure of the domestic dog". BioEssays 21: 247–257.  
  21. ^ Vilà, C.; Maldonado, J.E.; Wayne, R.K. (1999). "Phylogenetic relationships, evolution, and genetic diversity of the domestic dog". Journal of Heredity 90: 71–77. 
  22. ^ "ITIS Report: Canis lupus familiaris". ITIS Data. Integrated Taxonomic Information System from 3rd Edition of the Mammal Species of the World (Wozencraft in Wilson & Reeder, 2005). Retrieved 21 October 2014. 
  23. ^ Gentry, Anthea; Clutton-Brock, Juliet; Groves, Colin P. (2004). "The naming of wild animal species and their domestic derivatives". Journal of Archaeological Science 31 (5): 645–651.  
  24. ^ Freedman, Adam H.; Gronau, Ilan; Schweizer, Rena M.; Ortega-Del Vecchyo, Diego; Han, Eunjung; Silva, Pedro M.; Galaverni, Marco; Fan, Zhenxin; Marx, Peter; Lorente-Galdos, Belen; Beale, Holly; Ramirez, Oscar; Hormozdiari, Farhad; Alkan, Can; Vilà, Carles; Squire, Kevin; Geffen, Eli; Kusak, Josip; Boyko, Adam R.; Parker, Heidi G.; Lee, Clarence; Tadigotla, Vasisht; Siepel, Adam; Bustamante, Carlos D.; Harkins, Timothy T.; Nelson, Stanley F.; Ostrander, Elaine A.; Marques-Bonet, Tomas; Wayne, Robert K.; Novembre, John (16 January 2014). "Genome Sequencing Highlights Genes Under Selection and the Dynamic Early History of Dogs". PLOS Genetics (PLOS Org) 10 (1): e1004016.  
  25. ^ O. Thalmann, B. Shapiro, P. Cui, V. J. Schuenemann, S. K. Sawyer, D. L. Greenfield, M. B. Germonpré, M. V. Sablin, F. López-Giráldez, X. Domingo-Roura, H. Napierala, H-P. Uerpmann, D. M. Loponte, A. A. Acosta, L. Giemsch, R. W. Schmitz, B. Worthington, J. E. Buikstra, A. Druzhkova, A. S. Graphodatsky, N. D. Ovodov, N. Wahlberg, A. H. Freedman, R. M. Schweizer, K.-P. Koepfli, J. A. Leonard, M. Meyer, J. Krause, S. Pääbo, R. E. Green, R. K. Wayne - Complete Mitochondrial Genomes of Ancient Canids Suggest a European Origin of Domestic Dogs - Science 15 November 2013: Vol. 342 no. 6160 pp. 871-874 DOI: 10.1126/science.1243650 Full Text available here
  26. ^ Man's best friend originated in Europe
  27. ^ Dates given vary somewhat: [1], [2], Britannica.
  28. ^ Dogs likely originated in Europe more than 18,000 years ago, UCLA biologists report
  29. ^ a b Miklósi, Adám (2007). Dog Behaviour, Evolution, and Cognition. Oxford University Press.  
  30. ^ Wingfield-Hayes, Rupert (29 June 2002). "China's taste for the exotic". BBC News. 
  31. ^ "Vietnam's dog meat tradition". BBC News. 31 December 2001. 
  32. ^ a b c Groves, Colin (1999). "The Advantages and Disadvantages of Being Domesticated". Perspectives in Human Biology 4: 1–12.  
  33. ^ a b c d e Tacon, Paul; Pardoe, Colin (2002). "Dogs make us human". Nature Australia 27 (4): 52–61. 
  34. ^ Ruusila, Vesa; Pesonen, Mauri (2004). )"Canis familiaris) hunting: the benefits of a barking dog (Homo sapiens"Interspecific cooperation in human (. Annales Zoologici Fennici 41 (4): 545–9. 
  35. ^ Newby, Jonica (1997). The Pact for Survival. Sydney: ABC Books.  
  36. ^ a b A History of Dogs in the Early Americas, Marion Schwartz, 1998, 260 p., ISBN 978-0-300-07519-9, Yale University Press
  37. ^ "The University of Maine - UMaine News - UMaine Student Finds Oldest Known Domesticated Dog in Americas". 11 January 2011. Retrieved 4 July 2013. 
  38. ^ Derr, Mark (2004). A dogs history of America. North Point Press.  p.12
  39. ^ a b Derr, Mark (1997). Dog's Best Friend. Chicago: University of Chicago Press.  
  40. ^ Franklin, A (2006). "Be[a]ware of the Dog: a post-humanist approach to housing". Housing Theory and Society 23 (3): 137–156.  
  41. ^ Katz, Jon (2003). The New Work of Dogs. New York: Villard Books.  
  42. ^ Haraway, Donna (2003). The Companion Species manifesto: Dogs, People and Significant Otherness. Chicago: Prickly Paradigm Press.  
  43. ^ a b c d e f Power, Emma (2008). "Furry Families: Making a Human-Dog Family through Home". Social and Cultural Geography 9 (5): 535–555.  
  44. ^ a b c Nast, Heidi J. (2006). "Loving ... Whatever: Alienation, Neoliberalism and Pet-Love in the Twenty-First Century". ACME: an International E-Journal for Critical Geographies 5 (2): 300–327.  
  45. ^ "A Brief History of Dog Training". Dog Zone. 3 June 2007. Retrieved 19 February 2010. 
  46. ^ Jackson Schebetta, Lisa (2009). "Mythologies and Commodifications of Dominion in The Dog Whisperer with Cesar Millan". Journal for Critical Animal Studies (Institute for Critical Animal Studies) 7 (1): 107–131.  
  47. ^ Bradshaw, John; Blackwell, Emily J.; Casey, Rachel A. (2009). "Dominance in domestic dogs: useful construct or bad habit?". Journal of Veterinary Behavior (Elsevier) 4 (3): 135–144.  
  48. ^ Tannen, Deborah (2004). "Talking the Dog: Framing Pets as Interactional Resources in Family Discourse". Research on Language and Social Interaction 37 (4): 399–420.  
  49. ^ "U.S. Pet Ownership Statistics". Retrieved 24 June 2010. 
  50. ^ James Edgar (21 February 2014). "Dogs and humans respond to voices in same way". The Daily Telegraph (London). 
  51. ^ "The Story of Old Drum". Cedarcroft Farm Bed & Breakfast — Warrensburg, MO. Retrieved 29 November 2006. 
  52. ^ Williams, Tully (2007). Working Sheep Dogs. Collingwood, Vic.: CSIRO Publishing.  
  53. ^ a b c d Serpell, James (1995). "Origins of the dog: domestication and early history". The Domestic Dog. Cambridge: Cambridge Univ. Press.  
  54. ^ a b c d e f g h i j Dewey, T. and S. Bhagat. 2002. "Canis lupus familiaris", Animal Diversity Web. Retrieved 6 January 2009.
  55. ^ "sputnik". Retrieved 25 September 2013. 
  56. ^ Solovyov, Dmitry; Pearce, Tim (ed.) (11 April 2008). "Russia fetes dog Laika, first earthling in space".  
  57. ^ "Psychiatric Service Dog Society". 1 October 2005. Retrieved 21 December 2010. 
  58. ^ "About Guide Dogs – Assistance Dogs International". Retrieved 21 December 2010. 
  59. ^ Dalziel DJ, Uthman BM, Mcgorray SP, Reep RL (2003). "Seizure-alert dogs: a review and preliminary study". Seizure 12 (2): 115–20.  
  60. ^ "German Shepherd Dog | American Kennel Club". American Kennel Club. Retrieved 28 December 2010. 
  61. ^ "A Beginner's Guide to Dog Shows". American Kennel Club. Retrieved 30 October 2008. 
  62. ^ Simoons, Frederick J. (1994). Eat not this flesh: food avoidances from prehistory to the present (second ed.). University of Wisconsin Press. pp. 208–212.  
  63. ^ "How many dogs and cats are eaten in Asia?". Retrieved 19 December 2012. 
  64. ^ "South Korea's dog day". BBC News. 17 August 1999. Retrieved 19 December 2012. 
  65. ^ a b Pettid, Michael J., Korean Cuisine: An Illustrated History, London: Reaktion Books Ltd., 2008, 25. ISBN 1-86189-348-5
  66. ^ "Inside the cat and dog meat market in China". CNN. 9 March 2010. Retrieved 24 June 2010. 
  67. ^ Day, Matthew (7 August 2009). "Polish couple accused of making dog meat delicacy". London: Retrieved 21 December 2010. 
  68. ^ Schwabe, Calvin W. (1979). Unmentionable Cuisine. Charlottesville: University Press of Virginia. p. 173.  
  69. ^ Questions and Answers about Dog Bites
  70. ^ a b "Statistics about dog bites in the USA and elsewhere". Retrieved 18 December 2012. 
  71. ^ Whitcomb, Rachael (1 July 2009). "Study: Chihuahuas bite vets most; Lhaso Apsos inflict worst injuries". DVM Newsmagazine. Retrieved 15 February 2013. 
  72. ^ Weiss, HB; Friedman, DI; Coben, JH (1998). "Incidence of dog bite injuries treated in emergency departments". JAMA 279 (1): 51–3.  
  73. ^ Tierney, DM; Strauss, LP; Sanchez, JL (2006). "Capnocytophaga canimorsus Mycotic Abdominal Aortic Aneurysm: Why the Mailman Is Afraid of Dogs". Journal of Clinical Microbiology 44 (2): 649–51.  
  74. ^ "Mail campaign over dog attacks". BBC News. 11 August 2005. 
  75. ^ "Injury Prevention Bulletin". Northwest Territories Health and Social Services. 25 March 2009. Retrieved 7 January 2010. 
  76. ^ Bewley, BR (1985). "Medical hazards from dogs". British Medical Journal 291 (6498): 760–1.  
  77. ^ Huh, Sun; Lee, Sooung (20 August 2008). "Toxocariasis". Retrieved 15 February 2013. 
  78. ^ a b "Toxocariasis". Kids' Health. The Nemours Foundation. 2010. Retrieved 12 February 2010. 
  79. ^ Johnson, Kate (May 2002). "Parasites in pet feces cause puzzling infections". Pediatric News. Retrieved 11 May 2009. 
  80. ^ Chiodo, Paula; Basualdo, Juan; Ciarmela, Laura; Pezzani, Betina; Apezteguía, María; Minvielle, Marta (2006). "Related factors to human toxocariasis in a rural community of Argentina". Memórias do Instituto Oswaldo Cruz 101 (4): 397–400.  
  81. ^ Talaizadeh, A. H.; Maraghi2, S.; Jelowdar, A.; Peyvasteh, M. (October–December 2007). "Human toxocariasis: A report of 3 cases". Pakistan Journal of Medical Sciences Quarterly 23 (5). Part I. 
  82. ^ "Dog fouling". UK: Woking Borough Council. Retrieved 21 December 2010. 
  83. ^ a b McNicholas, June; Gilbey, Andrew; Rennie, Ann; Ahmedzai, Sam; Dono, Jo-Ann; Ormerod, Elizabeth (2005). "Pet ownership and human health: A brief review of evidence and issues". BMJ 331 (7527): 1252–4.  
  84. ^ Podberscek, A.L. (2006). "Positive and Negative Aspects of Our Relationship with Companion Animals". Veterinary Research Communications 30 (1): 21–27.  
  85. ^ Winefield, Helen R.; Black, Anne; Chur-Hansen, Anna (2008). "Health effects of ownership of and attachment to companion animals in an older population". International Journal of Behavioral Medicine 15 (4): 303–10.  
  86. ^ Headey B. (1999). "Health benefits and health cost savings due to pets: preliminary estimates from an Australian national survey". Social Indicators Research 47 (2): 233–243.  
  87. ^ a b Serpell J (1991). "Beneficial effects of pet ownership on some aspects of human health and behaviour". Journal of the Royal Society of Medicine 84 (12): 717–20.  
  88. ^ Friedmann E, Thomas SA (1995). "Pet ownership, social support, and one-year survival after acute myocardial infarction in the Cardiac Arrhythmia Suppression Trial (CAST)". The American Journal of Cardiology 76 (17): 1213–7.  
  89. ^ Wilson CC (1991). "The pet as an anxiolytic intervention". The Journal of Nervous and Mental Disease 179 (8): 482–9.  
  90. ^ McNicholas, J.; Collis, G. M. (2006). "Animals as social supports: Insights for understanding animal assisted therapy". In Fine, Aubrey H. Handbook on animal-assisted therapy: theoretical foundations and guidelines for practice. Amsterdam: Elsevier/Academic Press. pp. 49–71.  
  91. ^ Eddy J, Hart LA, Boltz RP (1988). "The effects of service dogs on social acknowledgments of people in wheelchairs". The Journal of Psychology 122 (1): 39–45.  
  92. ^ Kruger, K.A. & Serpell, J.A. (2006). Animal-assisted interventions in mental health: Definitions and theoretical foundations, In Fine, A.H. (Ed.), Handbook on animal-assisted therapy: Theoretical foundations and guidelines for practice. San Diego, CA, Academic Press: 21–38. ISBN 0-12-369484-1
  93. ^ Batson, K.; McCabe, B.; Baun, M.M.; Wilson, C. (1998). "The effect of a therapy dog on socialization and psychological indicators of stress in persons diagnosed with Alzheimer's disease". In Turner, Dennis C.; Wilson, Cindy C. Companion animals in human health. Thousand Oaks: Sage Publications. pp. 203–15.  
  94. ^ Katcher, A.H.; Wilkins, G.G. (2006). "The Centaur's Lessons: Therapeutic education through care of animals and nature study". In Fine, Aubrey H. Handbook on animal-assisted therapy: theoretical foundations and guidelines for practice. Amsterdam: Elsevier/Academic Press. pp. 153–77.  
  95. ^ Terry Gasking. "How my dog sniffed out breast cancer and saved my lifeYYY". Retrieved November 22, 2014. 
  96. ^ "Medal for the heroic dog who sniffed out her owner's cancer: Daisy the Labrador has helped find disease in 551 patients". November 21, 2014. 
  97. ^ Animals abandoned as recession hits home. 22 December 2008.
  98. ^ HSUS Pet Overpopulation Estimates The Humane Society of the United States
  99. ^ "ASPCA Pet Statistics". Retrieved 8 August 2012. 
  100. ^ Palika, Liz (4 February 2004). Purebred Rescue Dog Adoption: Rewards and Realities. Howell Book House.  
  101. ^ "World's Largest Dog". Retrieved 7 January 2008. 
  102. ^ "Guinness World Records – Tallest Dog Living". Guinness World Records. 31 August 2004. Archived from the original on 11 July 2011. Retrieved 7 January 2009. 
  103. ^ a b c d e f g h i j k l m n o p q r s t u v Coren, Stanley (2004). How Dogs Think. First Free Press, Simon & Schuster.  
  104. ^ a b A&E Television Networks (1998). Big Dogs, Little Dogs: The companion volume to the A&E special presentation. A Lookout Book. GT Publishing.  
  105. ^ a b c Alderton, David (1984). The Dog. Chartwell Books.  
  106. ^ Jennifer Davis (1998). "Dr. P's Dog Training: Vision in Dogs & People". Retrieved 6 June 2008. 
  107. ^ "Dogs CAN see in colour: Scientists dispel the myth that canines can only see in black and white". Daily Mail (London). 23 July 2013. 
  108. ^ Anna A. Kasparson, Jason Badridze, Vadim V. Maximov (Jul 2013). "Colour cues proved to be more informative for dogs than brightness". Proceedings of the Royal Society B: Biological Sciences 280 (1766).  
  109. ^ Jay Neitz, Timothy Geist, Gerald H. Jacobs (1989). "Color Vision in the Dog". Visual neuroscience 3: 119–125.  
  110. ^ Jay Neitz, Joseph Carroll, Maureen Neitz (Jan 2001). "Color Vision — Almost Reason Enough for Having Eyes". Optics \& Photnics News: 26–33. 
  111. ^ a b Miklósi, p. 140.
  112. ^ a b Mech, David. Wolves, Behavior, Ecology, and Conservation. The University of Chicago Press, 2006, p. 98.
  113. ^ Miklósi, p. 139.
  114. ^ Jonica Newby, Caroline Penry-Davey (25 September 2003). "Catalyst: Dogs' Eyes". Australian Broadcasting Corporation. Retrieved 26 November 2006. 
  115. ^ Miklósi, p. 142.
  116. ^ a b Elert, Glenn; Timothy Condon (2003). "Frequency Range of Dog Hearing". The Physics Factbook. Retrieved 22 October 2008. 
  117. ^ "How well do dogs and other animals hear". Retrieved 7 January 2008. 
  118. ^ a b "Dog Sense of Hearing". Retrieved 22 October 2008. 
  119. ^ "Smell". 6 May 2004. Archived from the original on 1 August 2008. Retrieved 22 October 2008. 
  120. ^ Dijkgraaf S.;Vergelijkende dierfysiologie;Bohn, Scheltema en Holkema, 1978, ISBN 90-313-0322-4
  121. ^ Klappenbach, Laura (2008). "What is Counter Shading?". Retrieved 22 October 2008. 
  122. ^ Cunliffe, Juliette (2004). "Coat Types, Colours and Markings". The Encyclopedia of Dog Breeds. Paragon Publishing. pp. 20–23.  
  123. ^ "The Case for Tail Docking". Council of Docked Breeds. Retrieved 22 October 2008. 
  124. ^ "'"Bourbonnais pointer or 'short tail pointer. Retrieved 19 December 2012. 
  125. ^ Spady TC, Ostrander EA (January 2008). "Canine Behavioral Genetics: Pointing Out the Phenotypes and Herding up the Genes". American Journal of Human Genetics 82 (1): 10–8.  
  126. ^ The Complete dog book: the photograph, history, and official standard of every breed admitted to AKC registration, and the selection, training, breeding, care, and feeding of pure-bred dogs. New York, N.Y: Howell Book House. 1992.  
  127. ^ Savolainen P, Zhang YP, Luo J, Lundeberg J, Leitner T (November 2002). "Genetic evidence for an East Asian origin of domestic dogs". Science 298 (5598): 1610–3.  
  128. ^ The Merriam-Webster Editorial Staff, ed. (1967). Webster's Third New International Dictionary of the English Language, Unabridged. Springfield, MA U.S.A.: G&C Merriam Company. p. 2476. type (4a) the combination of character that fits an individual to a particular use or function (a strong horse of the draft type) 
  129. ^ a b c Parker, Heidi G.; Kim, Lisa V.; Sutter, Nathan B.; Carlson, Scott; Lorentzen, Travis D.; Malek, Tiffany B.; Johnson, Gary S.; DeFrance, Hawkins B.; Ostrander, Elaine A.; Kruglyak, Leonid (2004). "Genetic structure of the purebred domestic dog". Science 304 (5674): 1160–4.  
  130. ^ Ostrander, Elaine A. (September–October 2007). "Genetics and the Shape of Dogs; Studying the new sequence of the canine genome shows how tiny genetic changes can create enormous variation within a single species". American Scientist (online). pp. also see chart page 4. Retrieved 22 September 2008. 
  131. ^ Plants poisonous to dogs -
  132. ^ C. L. Winek, J. Butala, S. P. Shanor, and
    F. W. Fochtman, (1978) Toxicology of Poinsettia. Clinical Toxicology 13( l), pp. 27-45
  133. ^ Ward, Dr. Ernie. "Diseases shared by humans and pets". Retrieved 2 October 2010. 
  134. ^ "Kennel Club/British Small Animal Veterinary Association Scientific Committee". 2004. Retrieved 5 July 2007. 
  135. ^ a b Proschowsky, H. F., H. Rugbjerg, and A. K. Ersbell (2003). "Mortality of purebred and mixed-breed dogs in Denmark". Preventive Veterinary Medicine 58 (1–2): 63–74.  
  136. ^ a b Michell AR (1999). "Longevity of British breeds of dog and its relationships with sex, size, cardiovascular variables and disease". The Veterinary Record 145 (22): 625–9.  
  137. ^ a b c d Compiled by Cassidy, K. M. "Dog Longevity Web Site, Breed Data page". Retrieved 8 July 2007. 
  138. ^ Patronek GJ, Waters DJ, Glickman LT (1997). "Comparative longevity of pet dogs and humans: implications for gerontology research". The Journals of Gerontology. Series a, Biological Sciences and Medical Sciences 52 (3): B171–8.  
  139. ^ AnAge entry for Canis familiaris AnAge Database. Human Aging Genomic Resources. Retrieved 17 July 2007.
  140. ^ "Pusuke, world's oldest living dog, dies in Japan". 7 December 2011. 
  141. ^ a b Boitani, Luigi; Mech, L. David (2003). Wolves: behavior, ecology, and conservation. Chicago: University of Chicago Press. p. 448.  
  142. ^ Graves, Will (2007). Wolves in Russia: Anxiety throughout the ages. Calgary: Detselig Enterprises. p. 222.  
  143. ^ Kojola, I., Ronkainen, S., Hakala, A., Heikkinen, S., Kokko, S. "Interactions between wolves Canis lupus and dogs C. familiaris in Finland". Nordic Council for Wildlife Research. 
  144. ^ Scott, Jonathan & Scott, Angela (2006). Big Cat Diary: Leopard. London: Collins. p. 108.  
  145. ^ Perry, Richard (1965). The World of the Tiger. p. 260. ASIN: B0007DU2IU. 
  146. ^ (Linnaeus, 1758)"Hyaena (Hyaena) hyaena"Striped Hyaena . IUCN Species Survival Commission Hyaenidae Specialist Group. Archived from the original on 28 September 2007. Retrieved 21 May 2008. 
  147. ^ Marc Bekoff; Dale Jamieson (2006). "Ethics and the Study of Carnivores". Animal passions and beastly virtues. Temple University Press.  
  148. ^ Hazard, Evan B. (1982). "Order Carnivora". The mammals of Minnesota. U of Minnesota Press.  
  149. ^ S. G. Pierzynowski; R. Zabielski (1999). Biology of the pancreas in growing animals. Volume 28 of Developments in animal and veterinary sciences. Elsevier Health Sciences. p. 417.  
  150. ^ National Research Council (U.S.). Ad Hoc Committee on Dog and Cat Nutrition (2006). Nutrient requirements of dogs and cats. National Academies Press. p. 137.  
  151. ^ Smith, Cheryl S. (2008). "Chapter 6, Omnivores Together". Grab Life by the Leash: A Guide to Bringing Up and Bonding with Your Four-Legged Friend. John Wiley and Sons.  
  152. ^ Axelsson, E.; Ratnakumar, A.; Arendt, M. L.; Maqbool, K.; Webster, M. T.; Perloski, M.; Liberg, O.; Arnemo, J. M.; Hedhammar, Å.; Lindblad-Toh, K. (2013). "The genomic signature of dog domestication reveals adaptation to a starch-rich diet". Nature 495 (7441): 360–364.  
  153. ^ Sources vary on which of these are considered the most significant toxic item.
  154. ^ Murphy, L. A.; Coleman, A. E. (2012). "Xylitol Toxicosis in Dogs". Veterinary Clinics of North America: Small Animal Practice 42 (2): 307.  
  155. ^ "Toxic Foods and Plants for Dogs". Retrieved 24 June 2010. 
  156. ^ Drs. Foster & Smith. "Foods to Avoid Feeding Your Dog". Retrieved 24 June 2010. 
  157. ^  
  158. ^ "Sexual Maturity — Spay and Neuter". Archived from the original on 10 June 2009. Retrieved 22 October 2008. 
  159. ^ Concannon, P; Tsutsui, T; Shille, V (2001). "Embryo development, hormonal requirements and maternal responses during canine pregnancy". Journal of reproduction and fertility. Supplement 57: 169–79.  
  160. ^ "Dog Development - Embryology". 16 June 2013. Retrieved 22 September 2013. 
  161. ^ "Gestation in dogs". Retrieved 24 March 2013. 
  162. ^ "HSUS Pet Overpopulation Estimates". The Humane Society of the United States. Retrieved 22 October 2008. 
  163. ^ "French Bulldog Pet Care Guide". Archived from the original on 26 July 2011. Retrieved 7 January 2008. 
  164. ^ "Top 10 reasons to spay/neuter your pet". American Society for Prevention of Cruelty to Animals. Retrieved 16 May 2007. 
  165. ^ Mahlow, Jane C. (1999). "Estimation of the proportions of dogs and cats that are surgically sterilized". Journal of the American Veterinary Medical Association 215 (5): 640–643.  
  166. ^ Heidenberger E, Unshelm J, E (Feb 1990). "Changes in the behavior of dogs after castration". Tierärztliche Praxis (in German) 18 (1): 69–75.  
  167. ^ Morrison, Wallace B. (1998). Cancer in Dogs and Cats (1st ed.). Williams and Wilkins.  
  168. ^ Arnold S (1997). "[Urinary incontinence in castrated bitches. Part 1: Significance, clinical aspects and etiopathogenesis]". Schweizer Archiv Für Tierheilkunde (in German) 139 (6): 271–6.  
  169. ^ Johnston SD, Kamolpatana K, Root-Kustritz MV, Johnston GR, SD (Jul 2000). "Prostatic disorders in the dog". Anim. Reprod. Sci. 60–61: 405–15.  
  170. ^ Root-Kustritz MV (Dec 2007). "Determining the optimal age for gonadectomy of dogs and cats". JAVMA 231 (11): 1665–1675.  
  171. ^ a b c d e Fox, Michael W. (1971). Behaviour of Wolves, Dogs, and Related Canids (1st United States ed.). New York: Harper & Row. pp. 183–206.  
  172. ^ Coren, Stanley (1995). The Intelligence of Dogs: A Guide to the Thoughts, Emotions, and Inner Lives of Our Canine Companions. Bantam Books.  
  173. ^ "How Dogs Learn". National Animal Interest Alliance. Retrieved 4 July 2014. 
  174. ^ Adler, Leonore Loeb and Adler, Helmut E. (2004). "Ontogeny of observational learning in the dog (Canis familiaris)". Developmental Psychobiology 10 (3): 267–271.  
  175. ^ Kubinyi, E., Topal, J., & Miklosi, A. (2003). "Dogs (canis familiaris) learn their owners via observation in a manipulation task". Journal of Comparative Psychology 117 (2): 156.  
  176. ^ McKinley, Sue; Young, Robert J (2003). "The efficacy of the model-rival method when compared to operant conditioning for training domestic dogs to perform a retrieval-selection task". AABS 81 (4): 357.  
  177. ^ a b c Hare, B., Brown, M., Williamson, C., & Tomasello, M. (Nov 2002). "The domestication of social cognition in dogs". Science 298 (5598): 1634–6.  
  178. ^ K Guo, C Hall, S Hall, K Meints, D Mills (2007). "Left gaze bias in human infants, rhesus monkeys, and domestic dogs". Perception. 36 ECVP. Retrieved 24 June 2010. 
  179. ^ Alleyne, Richard (29 October 2008). "Dogs can read emotion in human faces". Daily Telegraph (London). Retrieved 24 June 2010. 
  180. ^ a b c Horowitz, Alexandra (2009). "Attention to attention in domestic dog (Canis familiaris) dyadic play". Journal Animal Cognition (Springer Berlin / Heidelberg) 12 (1): 107–18.  
  181. ^ Zimmer, Carl (22 April 2013). "A Virtual Pack, to Study Canine Minds". New York Times. Retrieved 30 April 2013. 
  182. ^ "Behaviour problems linked to pessimistic dogs". Sydney Morning Herald. 12 October 2010. Retrieved 21 October 2010. 
  183. ^ Sheridan, Kerry Smart US dog learns more than 1,000 words. The Age (8 January 2011)
  184. ^ Miklósi, Adam; Kubinyi E; Topál J; Gácsi M; Virányi Z; Csányi V. (29 April 2003). "A simple reason for a big difference: wolves do not look back at humans, but dogs do". Current Biology;13(9) 13 (9): 763–6.  
  185. ^ Kenth Svartberga, Björn Forkman, K; Forkman, Björn (14 June 2002). "Personality traits in the domestic dog (Canis familiaris)". Applied animal behavior science 79 (2): 133–155.  
  186. ^ Svartberg, K; Tapper, I; Temrin, H; Radesater, T; Thorman, S (February 2005). "Consistency of personality traits in dogs". Animal Behaviour 69 (2): 283–291.  
  187. ^ "40 Winks?" Jennifer S. Holland, National Geographic Vol. 220, No. 1. July 2011.
  188. ^ Do Dogs Dream? by Dr. Nicholas Dodman
  189. ^ Hart, Vlastimil; Petra Nováková, Erich Pascal Malkemper, Sabine Begall, Vladimír Hanzal, Miloš Ježek, Tomáš Kušta, Veronika Němcová, Jana Adámková, Kateřina Benediktová, Jaroslav Červený and Hynek Burda (27 December 2013). "Dogs are sensitive to small variations of the Earth's magnetic field". Frontiers in Zoology.  
  190. ^ Faragó, T; Pongrácz P; Miklósi Á; Huber L; Virányi Z; Range, F (2010). Giurfa, Martin, ed. "Dogs' Expectation about Signalers' Body Size by Virtue of Their Growls". PLoS ONE 5 (12): e15175.  
  191. ^ a b c d e f Coppinger, Ray (2001). Dogs: a Startling New Understanding of Canine Origin, Behavior and Evolution. New York: Scribner.  
  192. ^ a b Pal SK (January 2005). "Parental care in free-ranging dogs, Canis familiaris". Applied Animal Behaviour Science 90 (1): 31–47.  
  193. ^ Günther Bloch: Die Pizza-Hunde. ISBN 978-3-440-10986-1
  194. ^ Eberhard Trumler, Mit dem Hund auf du; Zum Verständnis seines Wesens und Verhaltens; 4. Auflage Januar 1996; R. Piper GmbH & Co. KG, München
  195. ^ a b c d e f g Frank H; Frank MG (1982). "On the effects of domestication on canine social development and behavior". Applied Animal Ethology 8 (6): 507–525.  
  196. ^ "Are wolves and wolfdog hybrids trainable?". Wolf Park. Archived from the original on 15 June 2008. Retrieved 30 October 2008. 
  197. ^ "Wolf Training and Socialisation: Example #1". Wolf Park. Archived from the original on 10 February 2008. Retrieved 30 October 2008. 
  198. ^ a b c d e f g h Sherman, Josepha (August 2008). Storytelling: An Encyclopedia of Mythology and Folklore. Sharpe Reference. pp. 118–121.  
  199. ^ "Indian Myth and Legend: Chapter III. Yama, the First Man, and King of the Dead". Retrieved 4 July 2013. 
  200. ^ Fodor's Essential India: with Delhi, Rajasthan, Mumbai, and Kerala. Random House LLC. 7 May 2013.  



See also

Ancient Greek rhyton in the shape of a dog's head, made by Brygos, early 5th century BC. Jérôme Carcopino Museum, Department of Archaeology, Aleria
Ancient Greek black-figure pottery depicting the return of a hunter and his dog. Made in Athens between 550–530 BC, found in Rhodes
Riders and dogs. Ancient Greek Attic black-figure hydria, ca. 510–500 BC, from Vulci. Louvre Museum, Paris. 
William McElcheran's Cross Section-dogs Dundas (TTC) Toronto 
Detail of The Imperial Prince and his dog Nero by Jean-Baptiste Carpeaux 1865 Marble. Photographed at the Musée d'Orsay
A woodcut illustration from The history of four-footed beasts and serpents by Edward Topsell, 1658 

Gallery of dogs in art

In Judaism and Islam, dogs are viewed as unclean scavengers.[198] In Christianity, dogs represent faithfulness.[198] In Asian countries such as China, Korea, and Japan, dogs are viewed as kind protectors.[198] The role of the dog in Chinese mythology includes a position as one of the twelve animals which cyclically represent years (the zodiacal dog).

In Hindu mythology, Yama, the god of death owns two watch dogs who have four eyes. They are said to watch over the gates of Naraka.[199] Hunter god Muthappan from North Malabar region of Kerala has hunting Dog as his mount. Dogs are found in and out of the Muthappan Temple and offerings at the shrine take the form of bronze dog figurines.[200]

In Greek mythology, Cerberus is a three-headed watchdog who guards the gates of Hades.[198] In Norse mythology, a bloody, four-eyed dog called Garmr guards Helheim.[198] In Persian mythology, two four-eyed dogs guard the Chinvat Bridge.[198] In Philippine mythology, Kimat who is the pet of Tadaklan, god of thunder, is responsible for lightning. In Welsh mythology, Annwn is guarded by Cŵn Annwn.[198]

In mythology, dogs often serve as pets or as watchdogs.[198]

Tesem, an old Egyptian sighthound-like dog.


Cultural depictions

Dogs display much greater tractability than tame wolves, and are, in general, much more responsive to coercive techniques involving fear, aversive stimuli, and force than wolves, which are most responsive toward positive conditioning and rewards.[196] Unlike tame wolves, dogs tend to respond more to voice than hand signals.[197]


In 1982, a study to observe the differences between dogs and wolves raised in similar conditions took place.[195] The dog puppies preferred larger amounts of sleep at the beginning of their lives, while the wolf puppies were much more active.[195] The dog puppies also preferred the company of humans, rather than their canine foster mother, though the wolf puppies were the exact opposite, spending more time with their foster mother.[195] The dogs also showed a greater interest in the food given to them and paid little attention to their surroundings, while the wolf puppies found their surroundings to be much more intriguing than their food or food bowl.[195] The wolf puppies were observed taking part in agonistic play at a younger age, while the dog puppies did not display dominant/submissive roles until they were much older.[195] The wolf puppies were rarely seen as being aggressive to each other or towards the other canines.[195] On the other hand, the dog puppies were much more aggressive to each other and other canines, often seen full-on attacking their foster mother or one another. [195]

However, this difference was not observed in all domestic dogs. Regurgitating of food by the females for the young as well as care for the young by the males has been observed in domestic dogs, dingos as well as in other feral or semi-feral dogs. Regurgitating of food by the females and direct choosing of only one mate has been observed even in those semi-feral dogs of direct domestic dog ancestry. Also regurgitating of food by males has been observed in free-ranging domestic dogs.[192][194]

Domestic dogs can be monogamous.[192] Breeding in feral packs can be, but does not have to be restricted to a dominant alpha pair (such things also occur in wolf packs).[193] Male dogs are unusual among canids by the fact that they mostly seem to play no role in raising their puppies, and do not kill the young of other females to increase their own reproductive success.[53]:267 Some sources say that dogs differ from wolves and most other large canid species by the fact that they do not regurgitate food for their young, nor the young of other dogs in the same territory.[191]

Feral dogs are primarily scavengers, with studies showing that unlike their wild cousins, they are poor ungulate hunters, having little impact on wildlife populations where they are sympatric. However, feral dogs have been reported to be effective hunters of reptiles in the Galápagos Islands,[53]:267 and free ranging pet dogs are more prone to predatory behavior toward wild animals.

Dogs tend to be poorer than wolves at observational learning, being more responsive to instrumental conditioning.[191] Feral dogs show little of the complex social structure or dominance hierarchy present in wolf packs. For example, unlike wolves, the dominant alpha pairs of a feral dog pack do not force the other members to wait for their turn on a meal when scavenging off a dead ungulate as the whole family is free to join in. For dogs, other members of their kind are of no help in locating food items, and are more like competitors.[191]

Behavioral differences

Compared to equally sized wolves, dogs tend to have 20% smaller skulls, 30% smaller brains,[53]:35 as well as proportionately smaller teeth than other canid species.[191] Dogs require fewer calories to function than wolves. It is thought by certain experts that the dog's limp ears are a result of atrophy of the jaw muscles.[191] The skin of domestic dogs tends to be thicker than that of wolves, with some Inuit tribes favoring the former for use as clothing due to its greater resistance to wear and tear in harsh weather.[191]

Physical characteristics

Some dogs, like this Tamaskan Dog, look very much like wolves.

Differences from wolves

A new study in Budapest, Hungary, has found that dogs are able to tell how big another dog is just by listening to its growl. A specific growl is used by dogs to protect their food. The research also shows that dogs do not lie about their size, and this is the first time research has shown animals can determine another's size by the sound it makes. The test, using images of many kinds of dogs, showed a small and big dog and played a growl. The result showed that 20 of the 24 test dogs looked at the image of the appropriately sized dog first and looked at it longest.[190]

Dog growl

Dogs prefer, when they are off the leash and Earth's magnetic field is calm, to urinate and defecate with their bodies aligned on a north-south axis.[189]

The average sleep time of a dog is said to be 10.1 hours per day.[187] Like humans, dogs have two main types of sleep: Slow-wave sleep, then Rapid eye movement sleep, the state in which dreams occur.[188]

The existence and nature of personality traits in dogs have been studied (15329 dogs of 164 different breeds) and five consistent and stable "narrow traits" identified, described as playfulness, curiosity/fearlessness, chase-proneness, sociability and aggressiveness. A further higher order axis for shyness–boldness was also identified.[185][186]

Properly socialized dogs can interact with unfamiliar dogs of any size and shape and understand how to communicate.

Given that dogs abilities to use human social cues originated during the process of domestication, it is likely that individual dogs that were able to use social cues to predict the behavior of humans more flexibly than could their last common wolf ancestor were at a selective advantage.[177]

After undergoing training to solve a simple manipulation task, dogs that are faced with an insoluble version of the same problem look/gaze at the human, while socialized wolves do not.[184]

Although dogs have been the subject of a great deal of behaviorist psychology (e.g. Pavlov's dog), they do not enter the world with a psychological "blank slate".[103] Rather, dog behavior is affected by genetic factors as well as environmental factors.[103] Domestic dogs exhibit a number of behaviors and predispositions that were inherited from wolves.[103]


A Rico, another border collie who could remember at least 200 objects.[183]

A study found a third of dogs suffered from anxiety when separated from others.[182]

Coren has also argued that dogs demonstrate a sophisticated theory of mind by engaging in deception, which he supports with a number of anecdotes, including one example wherein a dog hid a stolen treat by sitting on it until the rightful owner of the treat left the room.[103] Although this could have been accidental, Coren suggests that the thief understood that the treat's owner would be unable to find the treat if it were out of view. Together, the empirical data and anecdotal evidence points to dogs possessing at least a limited form of theory of mind.[103][180] Similar research has been performed by Brian Hare of Duke University, who has shown that dogs outperform both great apes as well as wolves raised by humans in reading human communicative signals.[177](pp1634-6)[181]

Stanley Coren, an expert on dog psychology, states that these results demonstrated the social cognition of dogs can exceed that of even our closest genetic relatives, and that this capacity is a recent genetic acquisition that distinguishes the dog from its ancestor, the wolf.[103] Studies have also investigated whether dogs engaged in partnered play change their behavior depending on the attention-state of their partner.[180] Those studies showed that play signals were only sent when the dog was holding the attention of its partner. If the partner was distracted, the dog instead engaged in attention-getting behavior before sending a play signal.[180]

Psychology research has shown that humans' gaze instinctively moves to the left in order to watch the right side of a person's face, which is related to use of right hemisphere brain for facial recognition, including human facial emotions. Research at the University of Lincoln (2008) shows that dogs share this instinct when meeting a human being, and only when meeting a human being (i.e., not other animals or other dogs). As such they are the only non-primate species known to do so.[178][179]

Dogs also demonstrate sophisticated social cognition by associating behavioral cues with abstract meanings.[103] One such class of social cognition involves the understanding that others are conscious agents. Research has shown that dogs are capable of interpreting subtle social cues, and appear to recognize when a human or dog's attention is focused on them. To test this, researchers devised a task in which a reward was hidden underneath one of two buckets. The experimenter then attempted to communicate with the dog to indicate the location of the reward by using a wide range of signals: tapping the bucket, pointing to the bucket, nodding to the bucket, or simply looking at the bucket.[177](pp1634-6) The results showed that domestic dogs were better than chimpanzees, wolves, and human infants at this task, and even young puppies with limited exposure to humans performed well.[103]

Sergeant Stubby wearing his uniform and medals. Stubby participated in four offensives and 17 battles.

Dogs can also learn by mimicking human behaviors. 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% in a control group that did not watch the human manipulate the lever.[175] 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.[176]

Puppies learn behaviors quickly by following examples set by experienced dogs.[103] 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 that 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 left to solve the problem on their own.[103][174]

Dogs go through a series of stages of cognitive development. As with humans, the understanding that objects not being actively perceived still remain in existence (called object permanence) is not present at birth. It develops as the young dog learns to interact intentionally with objects around it, at roughly 8 weeks of age.[103]

The domestic dog has a predisposition to exhibit a social intelligence that is uncommon in the animal world.[103] Dogs are capable of learning in a number of ways, such as through simple reinforcement (e.g., classical or operant conditioning) and by observation.[173][103]

The Border Collie is considered to be one of the most intelligent breeds.[172]


Intelligence and behavior

Barking appears to have little more communication functions than excitement, fighting, the presence of a human, or simply because other dogs are barking.[171] Subtler signs such as discreet bodily and facial movements, body odors, whines, yelps, and growls are the main sources of actual communication.[171] The majority of these subtle communication techniques are employed at a close proximity to another, but for long-range communication only barking and howling are employed.[171]

By the age of four weeks, the dog has developed the majority of its vocalizations.[171] The dog is the most vocal canid and is unique in its tendency to bark in a myriad of situations.[171]


[170] as well as osteosarcoma, hemangiosarcoma, cruciate ligament rupture, obesity, and diabetes mellitus in either sex.[169] in males,prostate cancer and [168] in female dogs,urinary incontinence However, neutering increases the risk of [167]

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