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The dog or domestic dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a
domesticated Domestication is a sustained multi-generational relationship in which one group of organisms assumes a significant degree of influence over the reproduction and care of another group to secure a more predictable supply of resources from that sec ...
descendant of the
wolf The wolf (''Canis lupus''), also known as the gray wolf or grey wolf, is a large canine Canine may refer to: Zoology * dog-like mammals (i.e. members of the canid subfamily Caninae) ** ''Canis'', a genus including dogs, wolves, coyotes, an ...

wolf
which is characterized by an upturning tail. The dog derived from an ancient, extinct wolf, and the modern grey wolf is the dog's nearest living relative. The dog was the first species to be domesticated, by
hunter–gatherers A hunter-gatherer is a human Humans (''Homo sapiens'') are the most populous and widespread species of primates, characterized by bipedality, opposable thumbs, hairlessness, and intelligence allowing the use of culture, language and tools. T ...
over 15,000 years ago, before the development of agriculture. Due to their long association with humans, dogs have expanded to a large number of domestic individuals and gained the ability to thrive on a
starch Starch or amylum is a consisting of numerous units joined by s. This is produced by most green s for energy storage. Worldwide, it is the most common carbohydrate in human diets, and is contained in large amounts in s like , es, (corn), , ...
-rich diet that would be inadequate for other
canids Canidae (; from Latin, ''canis'', "dog") is a biological family Family ( la, familia, plural ') is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy; it is classified between order (biology), order and genus. A famil ...
. Over the millennia, dogs became uniquely adapted to human behavior, and the human-canine bond has been a topic of frequent study. The dog has been selectively bred over millennia for various behaviors, sensory capabilities, and physical attributes.
Dog breed A dog breed is a particular strain of dog that was purposefully bred by humans to perform specific tasks, such as herding, hunting, and guarding. Dogs are the most variable mammal on earth, with artificial selection producing around 450 globally ...
s vary widely in shape, size, and color. They perform many roles for humans, such as
hunting Hunting is the practice of seeking, pursuing and capturing or killing wildlife or feral animals. The most common reasons for humans to hunt are to harvest useful animal products (meat, fur/hide (skin), hide, bone/tusks, horn (anatomy), horn/an ...
,
herding Herding is the act of bringing individual animals together into a group (herd), maintaining the group, and moving the group from place to place—or any combination of those. Herding can refer either to the process of animals forming herds in ...
, pulling loads,
protection File:CDCA auto repair notice.jpg, Consumer protection laws often mandate the posting of informative notices, such as this one which appears in all Auto mechanic, automotive repair shops in California. Protection is any measure taken to guard ...
, assisting police and the
military A military, also known collectively as armed forces, is a heavily armed, highly organized force primarily intended for warfare War is an intense armed conflict between State (polity), states, governments, Society, societies, or pa ...
,
companionship The concept of interpersonal relationship involves social associations, connections, or affiliations between two or more people. Interpersonal relationships vary in their degree of intimacy or self-disclosure, but also in their duration, in th ...

companionship
,
therapy A therapy or medical treatment (often abbreviated tx, Tx, or Tx) is the attempted remediation of a health Health, according to the , is "a state of complete physical, and social and not merely the absence of and ".. (2006)''Constitution ...

therapy
, and
aiding disabled people In international relations, aid (also known as international aid, overseas aid, foreign aid, economic aid or foreign assistance) is – from the perspective of governments – a voluntary transfer of resources from one country to another. Aid ...

aiding disabled people
. This influence on human society has given them the
sobriquet A sobriquet ( ), or soubriquet, is a nickname A nickname (also moniker) is a substitute for the proper name of a familiar person, place or thing. Commonly used to express affection, a form of endearment, and sometimes amusement, it can also be u ...
of "
man's best friend "Man's best friend" is a common phrase used to describe domestic dog The domestic dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated form of wolf. The dog descended from an ancient, extinct wolf, with the modern g ...

man's best friend
."


Taxonomy

In 1758, the Swedish botanist and zoologist
Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his Nobility#Ennoblement, ennoblement as Carl von Linné#Blunt, Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomi ...

Carl Linnaeus
published in his ''
Systema Naturae ' (originally in Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman Republic ...
,'' the two-word naming of species (
binomial nomenclature In taxonomy Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer to a specific classification scheme. Originally used only ...
). ''
Canis ''Canis'' is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology Biology is the natural science that studies life and living organisms, including their an ...

Canis
'' is the
Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" or "to be in relation with") is "an appa ...

Latin
word meaning "dog," and under this
genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining (Circumscription (taxonomy), circumscribing) and classifying gr ...
, he listed the domestic dog, the
grey wolf The wolf (''Canis lupus''), also known as the gray wolf or grey wolf, is a large canine Canine may refer to: Zoology * dog-like mammals (i.e. members of the canid subfamily Caninae) ** ''Canis'', a genus including dogs, wolves, coyotes, an ...

grey wolf
, and the
golden jackal The golden jackal (''Canis aureus'') is a Evolution of the wolf#Wolf-like canids, wolf-like canid that is native to Southeast Europe, Southwest Asia, South Asia, and regions of Southeast Asia. Compared with the Arabian wolf (''Canis lupus arab ...

golden jackal
. He classified the domestic dog as ''Canis familiaris'' and, on the next page, classified the grey wolf as ''Canis lupus''. Linnaeus considered the dog to be a separate species from the wolf because of its upturning tail (''cauda recurvata''), which is not found in any other
canid Canidae (; from Latin, ''canis'', "dog") is a biological family Family ( la, familia, plural ') is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy; it is classified between order (biology), order and genus. A famil ...
. In 1999, a study of
mitochondrial DNA Mitochondrial DNA (mtDNA or mDNA) is the DNA Deoxyribonucleic acid (; DNA) is a molecule File:Pentacene on Ni(111) STM.jpg, A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five car ...

mitochondrial DNA
(mtDNA) indicated that the domestic dog may have originated from the grey wolf, with the
dingo The dingo (''Canis familiaris'', ''Canis familiaris dingo'', ''Canis dingo'', or ''Canis lupus dingo'') is an ancient (Basal (phylogenetics), basal) lineage of dog found in Australia (continent), Australia. Its taxonomic classification is deba ...

dingo
and
New Guinea singing dog The New Guinea singing dog or New Guinea Highland dog is an ancient ( basal) lineage of dog found in the New Guinea Highlands on the island of New Guinea. Once considered to be a separate species in its own right, under the name ''Canis hallstrom ...
breeds having developed at a time when human communities were more isolated from each other. In the third edition of ''
Mammal Species of the World ''Mammal Species of the World: A Taxonomic and Geographic Reference'' is a standard reference work in mammalogy In zoology, mammalogy is the study of mammals – a Class (biology), class of vertebrates with characteristics such as Homeothermy, ho ...
'' published in 2005, the
mammalogist In zoology Zoology ()The pronunciation of zoology as is typically regarded as nonstandard, though it is not uncommon. is the branch of biology that studies the animal kingdom, including the anatomy, structure, embryology, evolution, Biological ...
W. Christopher Wozencraft listed under the wolf ''Canis lupus'' its wild subspecies and proposed two additional subspecies, which formed the domestic dog clade: ''familiaris'', as named by Linneaus in 1758 and, ''dingo'' named by Meyer in 1793. Wozencraft included ''hallstromi'' (the New Guinea singing dog) as another name (
junior synonym The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently. In botanical nomenclature Botanical nomenclature is the formal, scientific naming of plants. It is related to, but distinct from Alpha taxonomy, taxono ...
) for the dingo. Wozencraft referred to the mtDNA study as one of the guides informing his decision. Mammalogists have noted the inclusion of ''familiaris'' and ''dingo'' together under the "domestic dog" clade with some debating it. In 2019, a workshop hosted by the
IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization An international organization (also known as an international institut ...
/Species Survival Commission's Canid Specialist Group considered the dingo and the New Guinea singing dog to be
feral in St. Kilda, Scotland, St Kilda, Scotland A feral animal or plant (from la, fera, 'a wild beast') is one that lives in the wild but is descended from Domestication, domesticated specimens. As with an introduced species, the introduction of ...

feral
''Canis familiaris'' and therefore did not assess them for the
IUCN Red List of Threatened Species The International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization An internationa ...
.


Evolution

The
Cretaceous–Paleogene extinction event The Cretaceous–Paleogene (K–Pg) extinction event (also known as the Cretaceous–Tertiary extinction) was a sudden of three-quarters of the and on , approximately 66 million years ago. With the exception of some species such as ...
occurred 65 million years ago and brought an end to the dinosaurs and the appearance of the first carnivorans. The name ''carnivoran'' is given to a member of the order
Carnivora Carnivora is an order of placental Placentalia is one of the three extant subdivisions of the class of animals Mammalia Mammals (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch ...
. Carnivorans possess a common arrangement of teeth called
carnassials Carnassials are paired upper and lower teeth modified in such a way as to allow enlarged and often self-sharpening edges to pass by each other in a shearing manner. This adaptation is found in the Order Carnivora Carnivora is an order of plac ...

carnassials
, in which the first lower molar and the last upper
premolar The premolars, also called premolar teeth A tooth (plural teeth) is a hard, calcification, calcified structure found in the jaws (or mouths) of many vertebrates and used to Mastication, break down food. Some animals, particularly carnivores, al ...
possess blade-like enamel
crowns '' File:서봉총 금관 금제드리개.jpg, The Seobongchong Golden Crown of Ancient Silla, which is 339th National Treasure of South Korea. It is basically following the standard type of Silla's Crown. It was excavated by Swedish Crown Prin ...
that act similar to a pair of shears for cutting meat. This dental arrangement has been modified by adaptation over the past 60 million years for diets composed of meat, for crushing vegetation, or for the loss of the carnassial function altogether as in seals, sea lions, and walruses. Today, not all carnivorans are
carnivores A carnivore , meaning "meat Meat is animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organ ...
, such as the insect-eating
Aardwolf The aardwolf (''Proteles cristata'') is an insectivorous A robber fly eating a hoverfly The giant anteater, a large insectivorous mammal An insectivore is a Carnivore, carnivorous plant or animal that eats insects. An alternative term ...

Aardwolf
. The carnivoran ancestors of the dog-like
caniforms Caniformia is a within the order consisting of "dog-like" carnivorans. They include dogs, bears, wolves, foxes, raccoons, badgers, and mustelids. The (, es and ) are also assigned to this group. The center of diversification for the Caniformia ...
and the cat-like
feliforms Feliformia is a suborder within the order Carnivora consisting of "cat-like" carnivorans, including Felidae, cats (large and small), hyenas, mongooses, viverrids, and related taxa. Feliformia stands in contrast to the other suborder of Carnivora, ...
began their separate evolutionary paths just after the end of the dinosaurs. The first members of the dog family
Canidae Canidae (; from Latin, ''canis'', "dog") is a of dog-like ns. A member of this family is called a canid (). There are three found within the canid family, which are the extinct and , and the extant . The Caninae are known as canines, and in ...
appeared 40 million years ago, of which only its subfamily the
Caninae The Caninae, known as canines, are one of three subfamily, subfamilies found within the Canidae, canid family. The other two canid subfamilies are the extinct Borophaginae and Hesperocyoninae. The Caninae includes all living canids and their most ...
survives today in the form of the wolf-like and fox-like canines. Within the Caninae, the first members of genus ''
Canis ''Canis'' is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology Biology is the natural science that studies life and living organisms, including their an ...

Canis
'' appeared six million years ago, the ancestors of modern domestic dogs, wolves,
coyotes The coyote (''Canis latrans'') is a species of canis, canine native to North America. It is smaller than its close relative, the wolf, and slightly smaller than the closely related eastern wolf and red wolf. It fills much of the same ecological ...

coyotes
, and golden jackals.


Domestication

The earliest remains generally accepted to be those of a domesticated dog were discovered in Bonn-Oberkassel, Germany. Contextual, isotopic, genetic, and morphological evidence shows that this dog was not a local wolf. The dog was dated to 14,223 years ago and was found buried along with a man and a woman, all three having been sprayed with red
hematite Hematite (), also spelled as haematite, is a common iron oxide Iron oxides are chemical compounds composed of iron and oxygen Oxygen is the chemical element with the chemical symbol, symbol O and atomic number 8. It is a member o ...

hematite
powder and buried under large, thick basalt blocks. The dog had died of
canine distemper Canine distemper (sometimes termed footpad disease) is a viral disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not due to any immediate ...

canine distemper
. Earlier remains dating back to 30,000 years ago have been described as
Paleolithic dog The Paleolithic dog was a Late Pleistocene The Late Pleistocene is an unofficial age in the international geologic timescale in chronostratigraphy, also known as Upper Pleistocene from a stratigraphic perspective. It is intended to be the f ...
s but their status as dogs or wolves remains debated because considerable morphological diversity existed among wolves during the
Late Pleistocene The Late Pleistocene is an unofficial Age (geology), age in the international geologic timescale in chronostratigraphy, also known as Upper Pleistocene from a Stratigraphy, stratigraphic perspective. It is intended to be the fourth division of ...
. This timing indicates that the dog was the first species to be domesticated in the time of
hunter–gatherers A hunter-gatherer is a human Humans (''Homo sapiens'') are the most populous and widespread species of primates, characterized by bipedality, opposable thumbs, hairlessness, and intelligence allowing the use of culture, language and tools. T ...
, which predates agriculture.
DNA sequences A nucleic acid sequence is a succession of bases signified by a series of a set of five different letters that indicate the order of nucleotides Nucleotides are organic molecules , CH4; is among the simplest organic compounds. In chemistry, ...
show that all ancient and modern dogs share a common ancestry and descended from an ancient, extinct wolf population which was distinct from the lineage. Most dogs form a sister group to the remains of a Late Pleistocene wolf found in the Kessleroch cave near
Thayngen Thayngen () is a village and a municipality A municipality is usually a single administrative division having Municipal corporation, corporate status and powers of self-government or jurisdiction as granted by national and regional laws to whi ...
in the canton of
Schaffhausen Schaffhausen (; gsw, Schafuuse; french: Schaffhouse; it, Sciaffusa; rm, Schaffusa; en, Shaffhouse) is a town with historic roots, a municipality A municipality is usually a single administrative division Administrative division ...

Schaffhausen
,
Switzerland , french: Suisse(sse), it, svizzero/svizzera or , rm, Svizzer/Svizra , government_type = Federalism, Federal semi-direct democracy under an assembly-independent Directorial system, directorial republic , leader_title1 = Fe ...

Switzerland
, which dates to 14,500 years ago. The
most recent common ancestor In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanis ...
of both is estimated to be from 32,100 years ago. This indicates that an extinct Late Pleistocene wolf may have been the ancestor of the dog, with the modern wolf being the dog's nearest living relative. The dog is a classic example of a domestic animal that likely travelled a
commensal Commensalism is a long-term biological interaction In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their phy ...

commensal
pathway into domestication. The questions of when and where dogs were first domesticated have taxed geneticists and archaeologists for decades. Genetic studies suggest a domestication process commencing over 25,000 years ago, in one or several wolf populations in either Europe, the high Arctic, or eastern Asia. In 2021, a
literature review A literature review is an overview of the previously published works on a specific topic. The term can refer to a full scholarly paper or a section of a scholarly work such as a book, or an article. Either way, a literature review is supposed t ...
of the current evidence
infer Inferences are steps in reasoning, moving from premises to logical consequences; etymologically, the word ''wikt:infer, infer'' means to "carry forward". Inference is theoretically traditionally divided into deductive reasoning, deduction and ind ...

infer
s that the dog was domesticated in
Siberia Siberia (; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part of R ...

Siberia
23,000 years ago by ancient North Siberians, then later dispersed eastward into the Americas and westward across Eurasia.


Breeds

Dogs are the most variable mammal on earth with around 450 globally recognized
dog breeds The dog or domestic dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated Domestication is a sustained multi-generational relationship in which one group of organisms assumes a significant degree of influence over the r ...
. In the
Victorian era In the history of the United Kingdom The history of the United Kingdom began in the early eighteenth century with the Treaty of Union A treaty is a formal, legally binding written agreement between actors in international l ...
, directed human
selection Selection may refer to: In science: * Selection (biology) Natural selection is the differential survival and reproduction of individuals due to differences in phenotype right , Here the relation between genotype and phenotype is ill ...
developed the modern
dog breeds The dog or domestic dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated Domestication is a sustained multi-generational relationship in which one group of organisms assumes a significant degree of influence over the r ...
, which resulted in a vast range of phenotypes. Most breeds were derived from small numbers of founders within the last 200 years, and since then dogs have undergone rapid
phenotypic In genetics Genetics is a branch of biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular inter ...

phenotypic
change and were formed into today's modern breeds due to
artificial selection This Chihuahua (dog), Chihuahua mixed-breed dog, mix and Great Dane shows the wide range of dog breed sizes created using selective breeding. Selective breeding (also called artificial selection) is the process by which humans use animal breed ...
imposed by humans. The skull, body, and limb proportions vary significantly between breeds, with dogs displaying more phenotypic diversity than can be found within the entire order of carnivores. These breeds possess distinct traits related to morphology, which include body size, skull shape, tail phenotype, fur type and colour. Their behavioural traits include guarding, herding, and hunting, retrieving, and scent detection. Their personality traits include hypersocial behavior, boldness, and aggression, which demonstrates the functional and behavioral diversity of dogs. As a result, today dogs are the most abundant carnivore species and are dispersed around the world. The most striking example of this dispersal is that of the numerous modern breeds of European lineage during the
Victorian era In the history of the United Kingdom The history of the United Kingdom began in the early eighteenth century with the Treaty of Union A treaty is a formal, legally binding written agreement between actors in international l ...
.


Biology


Anatomy


Skeleton

All healthy dogs, regardless of their size and type, have an identical
skeletal The skeleton refers to the frames of support of animal bodies. There are several different skeletal types: the exoskeleton An exoskeleton (from Greek έξω, ''éxō'' "outer" and σκελετός, ''skeletós'' "skeleton") is the external sk ...

skeletal
structure with the exception of the number of bones in the tail, although there is significant skeletal variation between dogs of different types. The dog’s skeleton is well adapted for running; the
vertebrae In the vertebrate spinal column The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord (a flexible rod of uniform c ...
on the neck and back have extensions for powerful back muscles to connect to, the long ribs provide plenty of room for the heart and lungs, and the shoulders are unattached to the skeleton allowing great flexibility. Compared to the dog's wolf-like ancestors, selective breeding since domestication has seen the dog’s skeleton greatly enhanced in size for larger types as
mastiff A mastiff is a large and powerful type of dog The domestic dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated form of wolf. The dog descended from an ancient, extinct wolf, with the modern grey wolf being the dog ...

mastiff
s and miniaturised for smaller types such as
terrier Terrier (from the French word ''terrier'' , meaning "burrow") is a Dog type, type of dog originally bred to hunt vermin. A terrier is a dog of any one of many Dog breed, breeds or landraces of the terrier Dog type, type, which are typically small ...

terrier
s;
dwarfism Dwarfism occurs when an organism is exceptionally small. In humans, it is sometimes defined as Short stature, an adult height of less than , regardless of sex; the average adult height among people with dwarfism is , although some individuals ...
has been selectively utilised for some types where short legs are advantageous such as
dachshund The dachshund ( or ; German: "badger Badgers are short-legged omnivore An omnivore () is an animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animal ...

dachshund
s and
corgi The Welsh Corgi ( or Corgi, plural Corgis, or occasionally the etymologically consistent Corgwn; ) is a small type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, coll ...

corgi
s. Most dogs naturally have 26 vertebrae in their tails, but some with naturally short tails have as few as three. The dog's skull has identical components regardless of breed type, but there is significant divergence in terms of skull shape between types. The three basic skull shapes are the elongated dolichocephalic type as seen in
sighthound : characteristic long legs, deep chest, and narrow waist of a sighthound Sighthounds, also called gazehounds, are a Dog type, type of dog, hounds that hunt primarily by sight and speed, rather than by scent and endurance as scent hounds do. Appea ...
s, the intermediate mesocephalic or mesaticephalic type, and the very short and broad brachycephalic type exemplified by mastiff type skulls.


Senses

A dog's senses include vision, hearing, smell, taste, touch, and sensitivity to Earth's magnetic field. Another study has suggested that dogs can see Earth's magnetic field.


Coat

The
coat A coat typically is an outer garment Clothing (also known as clothes, apparel, and attire) are items worn on the body. Typically, clothing is made of fabrics or textile A textile is a flexible material made by creating an inter ...

coat
s of domestic dogs are of two varieties: "double" being familiar with dogs (as well as wolves) originating from colder climates, made up of a coarse
guard hair Fur is a thick growth of hair that covers the skin of many different animals, particularly mammals. It consists of a combination of oily #Guard hair, guard hair on top and thick #Down hair, underfur beneath. The guard hair keeps moisture from re ...
and a soft
down hair Fur is a thick growth of hair Hair is a protein filament In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular bio ...
, or "single," with the topcoat only. Breeds may have an occasional "blaze," stripe, or "star" of white fur on their chest or underside. Premature graying can occur in dogs from as early as one year of age; this is associated with
impulsive behavior In psychology, impulsivity (or impulsiveness) is a tendency to act on a Impulse (psychology), whim, displaying behavior characterized by little or no forethought, reflection, or consideration of the consequences. Impulsive actions are typically "po ...
s, s, fear of noise, and fear of unfamiliar people or animals.


Tail

There are many different shapes for s: straight, straight up, sickle, curled, or corkscrew. As with many canids, one of the primary functions of a dog's tail is to communicate their emotional state, which can be crucial in getting along with others. In some hunting dogs the tail is traditionally docked to avoid injuries.


Health

Some breeds of dogs are prone to specific genetic ailments such as
elbow The elbow is the visible joint between the upper and lower parts of the arm. It includes prominent landmarks such as the olecranon, the antecubital fossa, elbow pit, the Lateral epicondyle of the humerus, lateral and Medial epicondyle of the hum ...
and
hip dysplasia Hip dysplasia is an abnormality of the hip joint where the socket portion does not fully cover the ball portion, resulting in an increased risk for joint dislocation. Hip dysplasia may occur at birth or develop in early life. Regardless, it does ...
,
blindness Visual impairment, also known as vision impairment or vision loss, is a decreased ability to see to a degree that causes problems not fixable by usual means, such as glasses Glasses, also known as eyeglasses or spectacles, are vision eyew ...
,
deafness Deafness has varying definitions in cultural and medical contexts. In medical contexts, the meaning of deafness is hearing loss Hearing loss is a partial or total inability to hear Hearing, or auditory perception, is the ability ...
, ,
cleft palate A cleft lip contains an opening in the upper lip Lips are a visible body part at the mouth of many animals, including humans. Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech. Hu ...
, and
trick knee A luxating patella, sometimes called a trick knee, is a condition in which the patella, or kneecap, dislocates or moves out of its normal location. Patellar luxation is a common condition in dogs, particularly small and miniature breeds. The condit ...
s. Two severe medical conditions significantly affecting dogs are
pyometra Pyometra or pyometritis is a uterine infection. Though it is most commonly known as a disease of the unaltered female dog, it is also a notable human disease. It is also seen in female cattle Cattle, or cows (female) and bulls (male), are th ...

pyometra
, affecting unspayed females of all breeds and ages, and
Gastric dilatation volvulus Gastric dilatation volvulus (GDV), also known as gastric dilation, twisted stomach, or gastric torsion, is a medical condition that affects dogs in which the stomach The stomach is a muscular, hollow organ in the gastrointestinal tract of ...
(bloat), which affects larger breeds or deep-chested dogs. Both of these are acute conditions and can kill rapidly. Dogs are also susceptible to parasites such as
flea Flea, the common name for the order Order or ORDER or Orders may refer to: * Orderliness Orderliness is associated with other qualities such as cleanliness Cleanliness is both the abstract state of being clean and free from germs, dirt, tr ...
s,
tick Ticks (suborder Ixodida) are parasitic arachnid Arachnida () is a class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of in ...

tick
s,
mite Mites are small arachnid Arachnida () is a Class (biology), class of joint-legged invertebrate animals (arthropods), in the subphylum Chelicerata. Arachnida includes orders containing spiders (the largest order), scorpions, ticks, mites, op ...
s,
hookworm Hookworms are intestinal, blood-feeding, parasitic roundworms that cause types of infection known as helminthiases. Hookworm infection is found in many parts of the world, and is common in areas with poor access to adequate water, sanitation, ...
s,
tapeworm Eucestoda, commonly referred to as tapeworms, are the larger of the two subclasses Subclass may refer to: * Subclass (taxonomy), a taxonomic rank below "class" * Subclass (computer science) * Subclass (set theory) See also * Superclass (disa ...

tapeworm
s,
roundworm The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the valu ...

roundworm
s, and
heartworm ''Dirofilaria immitis'', also known as heartworm or dog heartworm, is a parasitic Parasitism is a Symbiosis, symbiotic biological interactions, relationship between species, where one organism, the parasite, lives on or inside another org ...

heartworm
s, which is a
roundworm The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the valu ...

roundworm
species that lives in the hearts of dogs. Several human foods and household ingestibles are toxic to dogs, including s, causing
theobromine poisoning Theobromine poisoning, also informally called chocolate poisoning, is an overdosage reaction to the xanthine Xanthine ( or ; archaically xanthic acid; systematic name 3,7-dihydropurine-2,6-dione) is a purine Purine is a heterocyclic compound ...
,
onion The onion (''Allium cepa'' L., from Latin ''cepa'' "onion"), also known as the bulb onion or common onion, is a vegetable Vegetables are parts of plants that are consumed by humans or other animals as food. The original meaning is still com ...

onion
s and
garlic Garlic (''Allium sativum'') is a species of bulbous flowering plant in the genus ''Allium''. Its close relatives include the onion, shallot, leek, chive, Allium fistulosum, Welsh onion and Allium chinense, Chinese onion. It is native to Central ...

garlic
, causing
thiosulphate Thiosulfate () (IUPAC-recommended spelling; sometimes thiosulphate in British English) is an Sulfur oxoacid, oxyanion of sulfur. The prefix thio- indicates that the thiosulfate ion is a sulfate ion with one oxygen replaced by sulfur. Thiosulfate h ...
,
sulfoxide A sulfoxide is a containing a sulfinyl (SO) attached to two carbon atoms. It is a polar functional group. Sulfoxides are the oxidized derivatives of . Examples of important sulfoxides are , a precursor to the compound that gives freshly crushed ...

sulfoxide
or
disulfide In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they underg ...
poisoning,
grape A grape is a fruit In botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term ...

grape
s and
raisin A raisin is a dried grape A grape is a fruit In botany, a fruit is the seed-bearing structure in flowering plants (also known as angiosperms) formed from the ovary after flowering. Fruits are the means by which angiosperms disse ...

raisin
s,
macadamia nut ''Macadamia'' is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer t ...

macadamia nut
s, and
xylitol Xylitol is a chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) composed of atoms from more than one chemical element, element held together by chemic ...

xylitol
. The nicotine in tobacco can also be dangerous to dogs. Signs of ingestion can include copious vomiting (e.g., from eating cigar butts) or
diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery defecation, bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration of ...
. Some other symptoms are abdominal pain, loss of coordination, collapse, or death. Dogs are also vulnerable to some of the same health conditions as humans, including
diabetes Diabetes mellitus, commonly known as just diabetes, is a group of metabolic disorders characterized by a hyperglycemia, high blood sugar level over a prolonged period of time. Symptoms often include frequent urination, Polydipsia, increased th ...
,
dental Dental may refer to: * Having to do with teeth * Dentistry, a medical profession dealing with teeth * Dental consonant, in linguistics * Dental Records, an independent UK record label * Dental_hygienist, Dental Hygienist, a person who cleans teeth ...
and
heart disease Cardiovascular disease (CVD) is a class of diseases that involve the heart The heart is a cardiac muscle, muscular Organ (biology), organ in most animals, which pumps blood through the blood vessels of the circulatory system. The pumped b ...
,
epilepsy Epilepsy is a group of non-communicable neurological disorder A neurological disorder is any disorder of the nervous system In Biology, biology, the nervous system is a Complex system, highly complex part of an animal that coordinates i ...

epilepsy
,
cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumor A benign tumor is a mass of cells Cell most often refers to: * Cell (biolo ...

cancer
,
hypothyroidism Hypothyroidism (also called ''underactive thyroid'', ''low thyroid'' or ''hypothyreosis'') is a disorder of the endocrine system in which the thyroid gland The thyroid, or thyroid gland, is an endocrine gland in the neck consisting of two ...

hypothyroidism
, and
arthritis Arthritis is a term often used to mean any disorder that affects joints A joint or articulation (or articular surface) is the connection made between bone A bone is a Stiffness, rigid tissue (anatomy), tissue that constitutes part of th ...
.


Lifespan

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. The median longevity of
mixed-breed dog File:Mongrel_dog.jpg, Spinone Italiano-German Shepherd, German Sheperd mixed-breed dog A mongrel, mutt or mixed-breed dog is a dog that does not belong to one officially recognized Dog breed, breed and is not the result of intentional Dog breed ...

mixed-breed dog
s, taken as an average of all sizes, is one or more years longer than that of purebred dogs when all breeds are averaged. For dogs in England, increased body weight has been found to be negatively correlated with longevity (i.e., the heavier the dog, the shorter its lifespan), and
mixed-breed dog File:Mongrel_dog.jpg, Spinone Italiano-German Shepherd, German Sheperd mixed-breed dog A mongrel, mutt or mixed-breed dog is a dog that does not belong to one officially recognized Dog breed, breed and is not the result of intentional Dog breed ...

mixed-breed dog
s live on average 1.2 years longer than
purebred dog A dog breed is a particular strain or dog type Dog types are broad categories of domestic dog The domestic dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated form of wolf. The dog descended from an ancient, ext ...
s.


Reproduction

In domestic dogs,
sexual maturity Sexual maturity is the capability of an organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxono ...

sexual maturity
happens around six months to one year for both males and females, although this can be delayed until up to two years of age for some large breeds, and is the time at which female dogs will have their first
estrous cycle The estrous cycle (, originally ) is the set of recurring physiological changes that are induced by reproductive hormones in most mammal Mammals (from Latin language, Latin , 'breast') are a group of vertebrate animals constituting the ...

estrous cycle
. They will experience subsequent estrous cycles semiannually, during which the body prepares for
pregnancy Pregnancy, also known as gestation, is the time during which one or more offspring In biology, offspring are the young creation of living organisms, produced either by a Asexual reproduction, single organism or, in the case of sexual repr ...

pregnancy
. At the peak of the cycle, females will become estrous, mentally and physically receptive to
copulation Sexual intercourse (or coitus or copulation) is a sexual activity typically involving the insertion and Pelvic thrust, thrusting of the penis into the vagina for Sexual stimulation, sexual pleasure, sexual reproduction, reproduction, or both.S ...
. Because the
ova , abbreviated as OVA and sometimes as OAV (original animation video), are Japanese animated films and series made specially for release in home video Home video is prerecorded media sold or Video rental shop, rented for home viewing. The ter ...

ova
survive and can be fertilized for a week after ovulation, more than one male can sire the same litter. Fertilization typically occurs two to five days after ovulation; 14–16 days after ovulation, the embryo attaches to the uterus and after seven to eight more days, a heartbeat is detectable. Dogs bear their litters roughly 58 to 68 days after
fertilization Fertilisation or fertilization (see American and British English spelling differences#-ise.2C -ize .28-isation.2C -ization.29, spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes ...

fertilization
, with an average of 63 days, although the length of gestation can vary. An average litter consists of about six
puppies A puppy is a Juvenile (organism), juvenile dog. Some puppies can weigh 1–1.5 kg (1-3 lb), while larger ones can weigh up to 7–11 kg (15-23 lb). All healthy puppies grow quickly after birth. A puppy's coat color may cha ...

puppies
.


Neutering

Neutering Neutering, from the Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the R ...
refers to the sterilization of animals, usually by or the female's
ovaries The ovary is an organ found in the female reproductive system 300px, 1. Labia_majora.html"_;"title="Vulva: 2. Labia_majora">Vulva: 2. Labia_majora; 3. Labia_minora; 4. Vulval_vestibule.html" "title="Labia_minora.html ...

ovaries
and
uterus The uterus (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the ...

uterus
, to eliminate the ability to procreate and reduce
sex drive Libido (; colloquial: sex drive) is a person's overall sexual drive or desire for sexual activity. In psychoanalytic theory libido is psychic drive or energy, particularly associated with sexual instinct, but also present in other instinctive ...

sex drive
. Because of dogs' overpopulation in some countries, many animal control agencies, such as the
American Society for the Prevention of Cruelty to Animals The American Society for the Prevention of Cruelty to Animals (ASPCA) is a non-profit organization A nonprofit organization (NPO), also known as a non-business entity, not-for-profit organization, or nonprofit institution, is a legal entity o ...
(ASPCA), advise that dogs not intended for further breeding should be neutered, so that they do not have undesired puppies that may later be euthanized. According to the
Humane Society of the United States#REDIRECT Humane Society of the United States The Humane Society of the United States (HSUS) is an American nonprofit organization that focuses on animal welfare Animal welfare is the well-being of non-human animals. Formal standards of animal ...
, three to four million dogs and cats are euthanized each year. Many more are confined to cages in shelters because there are many more animals than there are homes. Spaying or castrating dogs helps keep overpopulation down. Neutering reduces problems caused by
hypersexuality Hypersexuality is extremely frequent or suddenly increased libido Libido (; colloquial Colloquialism or colloquial language is the style (sociolinguistics), linguistic style used for casual communication. It is the most common functional s ...
, especially in male dogs. Spayed female dogs are less likely to develop cancers affecting the mammary glands, ovaries, and other reproductive organs. However, neutering increases the risk of
urinary incontinence Urinary incontinence (UI), also known as involuntary urination, is any uncontrolled leakage of urine. It is a common and distressing problem, which may have a large impact on quality of life Quality of life (QOL) is defined by the World Healt ...

urinary incontinence
in female dogs and
prostate cancer Prostate cancer is cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumor A benign tumor is a mass of cells Cell most o ...

prostate cancer
in males and
osteosarcoma An osteosarcoma (OS) or osteogenic sarcoma (OGS) (or simply bone cancer) is a cancerous tumor in a bone. Specifically, it is an aggressive malignant neoplasm that arises from primitive transformed cells of mesenchyme, mesenchymal origin (and thus a ...

osteosarcoma
,
hemangiosarcoma Hemangiosarcoma is a rapidly growing, highly invasive variety of cancer that occurs almost exclusively in dogs, and only rarely in cats, horses, mice, or humans (vinyl chloride toxicity). It is a sarcoma arising from the lining of blood vessels; t ...
,
cruciate ligament Cruciate ligaments (also cruciform ligaments) are pairs of ligament A ligament is the Connective tissue#Types, fibrous connective tissue that connects bones to other bones. It is also known as ''articular ligament'', ''articular larua'', ''fibr ...
rupture, obesity, and
diabetes mellitus Diabetes mellitus, commonly known as just diabetes, is a group of metabolic disorders characterized by a hyperglycemia, high blood sugar level over a prolonged period of time. Symptoms often include frequent urination, Polydipsia, increased th ...
in either sex.


Inbreeding depression

A common breeding practice for pet dogs is mating between close relatives (e.g., between half and full siblings).
Inbreeding depression Inbreeding depression is the reduced biological fitness Fitness (often denoted w or ω in population genetics models) is the quantitative representation of natural and sexual selection File:Sexual Selection with Peafowl.gif, 250px, Sexual se ...
is considered to be due mainly to the expression of homozygous deleterious recessive mutations. Outcrossing between unrelated individuals, including dogs of different breeds, results in the beneficial masking of deleterious recessive mutations in progeny. In a study of seven dog breeds (the
Bernese Mountain Dog The Bernese Mountain Dog (german: Berner Sennenhund) is a large dog breed, one of the four breeds of Sennenhund-dog type, type dogs from the Swiss Alps. These dogs have roots in the Roman mastiffs. The name ''Sennenhund'' is derived from the Germa ...

Bernese Mountain Dog
, ,
Cairn Terrier The Cairn Terrier is a terrier breed originating in the Scottish Highlands and recognized as one of Scotland's earliest working dogs. The breed was given the name Cairn because the breed's function was to hunt and chase quarry between the cairns ...

Cairn Terrier
,
Brittany Brittany (; french: link=no, Bretagne ; br, Breizh, or ; Gallo: ''Bertaèyn'' ) is a peninsula A peninsula ( la, paeninsula from ' "almost" and ' "island") is a landform surrounded by water on most of its border while being connected to ...
,
German Shepherd Dog The German Shepherd (german: link=no, Deutscher Schäferhund, ) is a breed of medium to large-sized working dog A working dog is a dog used to perform practical tasks, as opposed to pet or companion dogs. Definitions vary on what a working ...

German Shepherd Dog
, , and
West Highland White Terrier The West Highland White Terrier, commonly known as the Westie, is a from Scotland with a distinctive white harsh coat with a somewhat soft white undercoat. It is a medium-sized , although with longer legs than other Scottish breeds of terri ...

West Highland White Terrier
), it was found that inbreeding decreases litter size and survival. Another analysis of data on 42,855
Dachshund The dachshund ( or ; German: "badger Badgers are short-legged omnivore An omnivore () is an animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animal ...

Dachshund
litters found that as the
inbreeding coefficient Inbreeding is the production of offspring In biology, offspring are the young born of living organism, organisms, produced either by a single organism or, in the case of sexual reproduction, two organisms. Collective offspring may be known as ...
increased, litter size decreased and the percentage of stillborn puppies increased, thus indicating inbreeding depression. In a study of
Boxer Boxing is a combat sport A combat sport, or fighting sport, is a competitive contact sport that usually involves one-on-one combat. In many combat sports, a contestant wins by scoring more points than the opponent or by disabling the opponent ...

Boxer
litters, 22% of puppies died before reaching 7 weeks of age. Stillbirth was the most frequent cause of death, followed by infection. Mortality due to infection increased significantly with increases in inbreeding.


Behavior

Dog behavior is the internally coordinated responses (actions or inactions) of the domestic dog (individuals or groups) to internal and external stimuli. As the oldest domesticated species, dogs' minds inevitably have been shaped by millennia of contact with humans. As a result of this physical and social evolution, dogs have acquired the ability to understand and communicate with humans more than any other species and they are uniquely attuned to human behaviors. Behavioral scientists have uncovered a surprising set of social-cognitive abilities in domestic dogs. These abilities are not possessed by the dog's closest canine relatives or other highly intelligent mammals, such as
great ape The Hominidae (), whose members are known as great apes or hominids (), are a taxonomic Family (biology), family of primates that includes eight Neontology#Extant taxa versus extinct taxa, extant species in four Genus, genera: ''Orangutan, Pongo ...
s, but rather parallel to children's social-cognitive skills. Unlike other domestic species selected for production-related traits, dogs were initially selected for their behaviors. In 2016, a study found that only 11 fixed genes showed variation between wolves and dogs. These gene variations were unlikely to have been the result of natural evolution and indicate selection on both morphology and behavior during dog domestication. These genes have been shown to affect the pathway, with the majority of the genes affecting the fight-or-flight response (i.e., selection for tameness) and emotional processing. Dogs generally show reduced fear and aggression compared with wolves. Some of these genes have been associated with aggression in some dog breeds, indicating their importance in both the initial domestication and later in breed formation. Traits of high sociability and lack of fear in dogs may include genetic modifications related to
Williams-Beuren syndrome Williams syndrome (WS) is a genetic disorder A genetic disorder is a health problem caused by one or more abnormalities in the genome In the fields of molecular biology and genetics, a genome is all genetic information of an organis ...
in humans, which cause
hypersociabilityIn the context of transmedia storytelling, hypersociability is the encouraged involvement of media consumers in a story through ordinary social interaction.Henry Jenkins, ''Convergence Culture: Where Old and New Media Collide'' (New York: New York ...
at the expense of problem-solving ability.


Intelligence

Dog intelligence is the dog's ability to perceive information and retain it as knowledge for applying to solve problems. Studies of two dogs suggest that dogs can learn by inference and have advanced memory skills. A study with
Rico Rico or RICO may refer to: Places in the United States *Rico, Colorado Rico is an incorporated small town in Dolores County, Colorado, Dolores County, Colorado, United States. It was settled in 1879 as a silver mining center in the Pioneer Mining ...
, a
Border Collie The Border Collie is a working and Herding dog, herding dog breed developed in the Anglo-Scottish border region, for herding livestock, especially sheep. Considered highly Dog intelligence, intelligent, extremely energetic, acrobatic and athl ...

Border Collie
, showed that he knew the labels of over 200 different items. He inferred the names of novel things by exclusion learning and correctly retrieved those new items immediately and four weeks after the initial exposure. A study of another Border Collie, "Chaser," documented his learning and memory capabilities. He had learned the names and could associate by verbal command over 1,000 words. Dogs can read and react appropriately to human body language such as gesturing and pointing and human voice commands. One study of canine cognitive abilities found that dogs' capabilities are no more exceptional than those of other animals, such as
horse The horse (''Equus ferus caballus'') is a domesticated Domestication is a sustained multi-generational relationship in which one group of organisms assumes a significant degree of influence over the reproduction and care of another group to ...

horse
s,
chimpanzee The chimpanzee (''Pan troglodytes''), also known simply as chimp, is a species of Hominidae, great ape native to the forest and savannah of tropical Africa. It has four confirmed subspecies and a fifth proposed subspecies. The chimpanzee and t ...
s, or
cat The cat (''Felis catus'') is a domestic Domestic may refer to: In the home * Anything relating to the human home A home, or domicile, is a space used as a permanent or semi-permanent residence for an individual, group or family ...

cat
s. One limited study of 18 household dogs found that they lacked spatial memory, and were more focussed on the "what" of a task rather than the "where". Dogs demonstrate a
theory of mind In psychology Psychology is the scientific Science (from the Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area ar ...
by engaging in deception. An experimental study showed compelling evidence that Australian
dingo The dingo (''Canis familiaris'', ''Canis familiaris dingo'', ''Canis dingo'', or ''Canis lupus dingo'') is an ancient (Basal (phylogenetics), basal) lineage of dog found in Australia (continent), Australia. Its taxonomic classification is deba ...

dingo
s can outperform domestic dogs in non-social problem-solving, indicating that domestic dogs may have lost much of their original problem-solving abilities once they joined up with humans. Another study revealed that after undergoing training to solve a simple manipulation task, dogs faced with an insoluble version of the same problem look at the human, while socialized wolves do not.


Communication

Dog communication is how dogs convey information to other dogs, understand messages from humans and translate the information that dogs are transmitting. Communication behaviors of dogs include eye gaze, facial expression, vocalization, body posture (including movements of bodies and limbs), and gustatory communication (scents, pheromones, and taste). Humans communicate to dogs by using vocalization, hand signals, and body posture.


Ecology


Population

The dog is probably the most widely abundant large
carnivoran Carnivora is an order of placental mammal Mammals (from Latin language, Latin , 'breast') are a group of vertebrate animals constituting the class (biology), class Mammalia (), and characterized by the presence of mammary glands which i ...
living in the human environment. In 2013, the estimated global dog population was between 700 million and 987 million. About 20% of dogs live as pets in developed countries. In the developing world, dogs are more commonly feral or communally owned, with pet dogs uncommon. Most of these dogs live their lives as scavengers and have never been owned by humans, with one study showing their most common response when approached by strangers is to run away (52%) or respond aggressively (11%). Little is known about these dogs, or the dogs in developed countries that are feral, strays, or are in shelters because the great majority of modern research on dog cognition has focused on pet dogs living in human homes.


Competitors and predators

Although dogs are the most abundant and widely distributed terrestrial carnivores, feral and free-ranging dogs' potential to compete with other large carnivores is limited by their strong association with humans. For example, a review of the studies in dogs' competitive effects on
sympatric In biology, two related species In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, ...
carnivores did not mention any research on competition between dogs and wolves. Although wolves are known to kill dogs, they tend to live in pairs or in small packs in areas where they are highly persecuted, giving them a disadvantage facing large dog groups. Wolves kill dogs wherever they are found together. 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. Although the numbers of dogs killed each year are relatively low, it induces a fear of wolves entering villages and farmyards to take dogs and losses of dogs to wolves have led to demands for more liberal wolf hunting regulations.
Coyote The coyote (''Canis latrans'') is a of native to . It is smaller than its close relative, the , and slightly smaller than the closely related and . It fills much of the same as the does in . The coyote is larger and more predatory and was ...

Coyote
s and
big cat The term "big cat" is typically used to refer to any of the five living members of the genus '' Panthera'', namely the lion, tiger, jaguar, leopard, and snow leopard, as well as the non- pantherine cheetah and cougar. Except for the latter thr ...

big cat
s have also been known to attack dogs. In particular,
leopard The leopard (''Panthera pardus'') is one of the five extant in the ', a member of the cat , . It occurs in a wide range in , in some parts of and , , and on the to and . It is listed as on the because leopard populations are threatened ...

leopard
s are known to have a preference for dogs and have been recorded to kill and consume them, no matter what their size.
Siberian tiger The Siberian tiger is a tiger from a specific population of the ''Panthera tigris tigris'' subspecies native to the Russian Far East, Northeast China, and possibly North Korea. It once ranged throughout the Korean Peninsula, north China, and ea ...

Siberian tiger
s in the
Amur river The Amur (russian: река́ Аму́р, ), or Heilong Jiang (, "Black Dragon A dragon is a large, serpent Serpent or The Serpent may refer to: * Snake Snakes are elongated, limbless, carnivorous reptiles of the suborder Serpen ...

Amur river
region have killed dogs in the middle of villages. This indicates that the dogs were targeted. Amur tigers will not tolerate wolves as competitors within their territories, and the tigers could be considering dogs in the same way. Striped hyenas are known to kill dogs in their range.


Diet

Dogs have been described as omnivores. Compared to wolves, dogs from agricultural societies have Amylase#Evolution, extra copies of amylase and other genes involved in starch digestion that contribute to an increased ability to thrive on a starch-rich diet. Similar to humans, some dog breeds produce amylase in their saliva and are classified as having a high starch diet. However, more like cats and less like other omnivores, dogs can only produce bile acid with taurine and they cannot produce vitamin D, which they obtain from animal flesh. Also, more like cats, dogs require arginine to maintain its nitrogen balance. These nutritional requirements place dogs halfway between carnivores and omnivores.


Range

As a domesticated or semi-domesticated animal, the dog is nearly universal among human societies. Notable exceptions once included: * The Aboriginal Tasmanians, who were separated from Australia before the arrival of
dingo The dingo (''Canis familiaris'', ''Canis familiaris dingo'', ''Canis dingo'', or ''Canis lupus dingo'') is an ancient (Basal (phylogenetics), basal) lineage of dog found in Australia (continent), Australia. Its taxonomic classification is deba ...

dingo
s on that continent * The Andamanese peoples, who were isolated when Sea level rise, rising sea levels covered the land bridge to Myanmar * The Fuegians, who instead domesticated the Fuegian dog, a different canid species * Individual Pacific islands whose maritime settlers did not bring dogs, or where dogs died out after original settlement, notably the Mariana Islands, Palau and most of the Caroline Islands with exceptions such as Fais Island and Nukuoro, the Marshall Islands, the Gilbert Islands, New Caledonia, Vanuatu, Tonga, Marquesas, Mangaia in the Cook Islands, Rapa Iti in French Polynesia, Easter Island, the Chatham Islands and Pitcairn Island (settled by the Mutiny on the Bounty, ''Bounty'' mutineers, who killed off their dogs to escape discovery by passing ships). Dogs were introduced to Antarctica as sled dogs, but were later outlawed by international agreement due to the possible risk of spreading infections.


Roles with humans

Domestic dogs inherited complex behaviors, such as bite inhibition, from their wolf ancestors, which would have been pack hunters with a 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. These attributes have given dogs a relationship with humans that has enabled them to become one of the most successful animals today. 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 Hunting is the practice of seeking, pursuing and capturing or killing wildlife or feral animals. The most common reasons for humans to hunt are to harvest useful animal products (meat, fur/hide (skin), hide, bone/tusks, horn (anatomy), horn/an ...
,
herding Herding is the act of bringing individual animals together into a group (herd), maintaining the group, and moving the group from place to place—or any combination of those. Herding can refer either to the process of animals forming herds in ...
, pulling loads,
protection File:CDCA auto repair notice.jpg, Consumer protection laws often mandate the posting of informative notices, such as this one which appears in all Auto mechanic, automotive repair shops in California. Protection is any measure taken to guard ...
, assisting police and the
military A military, also known collectively as armed forces, is a heavily armed, highly organized force primarily intended for warfare War is an intense armed conflict between State (polity), states, governments, Society, societies, or pa ...
,
companionship The concept of interpersonal relationship involves social associations, connections, or affiliations between two or more people. Interpersonal relationships vary in their degree of intimacy or self-disclosure, but also in their duration, in th ...

companionship
and Assistance dog, aiding disabled individuals. This influence on human society has given them the nickname "
man's best friend "Man's best friend" is a common phrase used to describe domestic dog The domestic dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated form of wolf. The dog descended from an ancient, extinct wolf, with the modern g ...

man's best friend
" in the Western world. In some cultures, however, dogs #As food, are also a source of meat.


Pets

It is estimated that three-quarters of the world's dog population lives in the developing world as feral, village, or community dogs, with pet dogs uncommon. "The most widespread form of interspecies bonding occurs between humans and dogs" and the keeping of dogs as companions, particularly by elites, has a long history. Pet dog populations grew significantly after World War II as suburbanization increased. In the 1950s and 1960s, dogs were kept outside more often than they tend to be today(the expression "in the doghouse" - recorded since 1932 - to describe exclusion from the group implies a 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 pet dog's role, such as the increased role of dogs in the emotional support of their human guardians. People and their dogs have become increasingly integrated and implicated in each other's lives to the point where pet dogs actively shape how a family and home are experienced. There have been two significant trends occurring within the second half of the 20th century in pet dogs' changing status. The first has been Commodification of animals, "commodification," shaping it to conform to social expectations of personality and behavior.The second has been the broadening of the family's concept and the home to include dogs-as-dogs within everyday routines and practices. A vast range of commodity forms aims to transform a pet dog into an ideal companion. 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. Dog training books, classes, and television programs proliferated as the process of commodifying the pet dog continued. The majority of contemporary dog owners describe their pet as part of the family, although some ambivalence about the relationship is evident in the popular reconceptualization of the dog-human family as a pack. Some dog trainers, such as on the television program ''Dog Whisperer'', have promoted a Dominance (ethology), dominance model of dog-human relationships. However, it has been disputed that "trying to achieve status" is characteristic of dog-human interactions. 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. Increasingly, human family-members engage in activities centered on the dog's perceived needs and interests, or in which the dog is an integral partner, such as Musical canine freestyle, dog dancing and Doga (Dog Yoga), dog yoga. According to statistics published by the American Pet Products Manufacturers Association in the National Pet Owner Survey in 2009–2010, an estimated 77.5 million people in the United States have pet dogs. The same source shows that 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 (disambiguation), gender preference among dogs as pets, as the statistical data reveal an equal number of male and female pet dogs. Although several programs promote pet adoption, less than one-fifth of the owned dogs come from Animal shelter, shelters. A study using magnetic resonance imaging (MRI) to compare humans and dogs showed that dogs have the same response to voices and use the same parts of the brain as humans do. This gives dogs the ability to recognize human emotional sounds, making them friendly social pets to humans.


Workers

Dogs have lived and worked with humans in many roles. In addition to dogs' role as companion animals, dogs have been bred for herding livestock (collies, sheepdogs),Dewey, T. and S. Bhagat. 2002.
Canis lupus familiaris
Animal Diversity Web.
hunting (hounds, pointers) and rodent control (terriers). Other types of working dogs include search and rescue dogs, detection dogs trained to detect Illegal drug trade, illicit drugs or chemical weapons; guard dogs; dogs who assist fishermen with the use of nets; and dogs that pull loads. In 1957, the dog Laika became the first animal to be launched into Earth orbit, aboard the Soviet space program, Soviets' ''Sputnik 2''; she died during the flight. Various kinds of service dogs and assistance dogs, including guide dogs, hearing dogs, mobility assistance dogs and psychiatric service dogs, assist individuals with disabilities. Some dogs owned by people with epilepsy 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.


Athletes and models

People often enter their dogs in competitions, such as breed-conformation shows or List of dog sports, 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 dog's externally observable qualities (such as appearance, movement and temperament), separately tested qualities (such as ability or health) are not part of the judging in conformation shows.


Food

Dog meat is consumed in some East Asian countries, including Korea, China Vietnam and the Philippines, which dates back to antiquity. Based on limited data, it is estimated that 13–16 million dogs are killed and consumed in Asia every year. In China, debates have ensued over banning the consumption of dog meat. Following the Sui and Tang dynasties of the first millennium, however, people living on northern China's plains began to eschew eating dogs, which is likely due to Buddhism and Islam's spread, two religions that forbade the consumption of certain animals, including the dog. As members of the upper classes shunned dog meat, it gradually became a social taboo to eat it, even though the general population continued to consume it for centuries afterward. Dog meat is also consumed in some parts of Switzerland. Other cultures, such as Polynesia and pre-Columbian Mexico, also consumed dog meat in their history. Dog fat is also reportedly believed to be beneficial for the lungs in some parts of Poland and Central Asia. Proponents of eating dog meat have argued that placing a distinction between livestock and dogs is Western hypocrisy and that there is no difference in eating different animals' meat. In Korea, the primary dog breed raised for meat, the ''Nureongi'', differs from those breeds raised for pets that Koreans may keep in their homes.Pettid, Michael J., ''Korean Cuisine: An Illustrated History'', London: Reaktion Books Ltd., 2008, 25. The most popular Korean dog dish is 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 Qi, ''gi'', or the body's vital energy. A 19th-century version of bosintang 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 prevalent in Korea with a segment of the population, dog is not as widely consumed as beef, pork and chicken.


Health risks

In 2018, the WHO reported that 59,000 people died globally from rabies, with 59.6% in Asia and 36.4% in Africa. Rabies is a disease for which dogs are the most important vector. Significant dog bites affect tens of millions of people globally each year. Children in mid-to-late childhood are the largest percentage bitten by dogs, with a greater risk of injury to the head and neck. They are more likely to need medical treatment and have the highest death rate. Sharp claws with powerful muscles behind them can lacerate flesh in a scratch that can lead to serious infections. In the Dogs in the United States, U.S.,
cat The cat (''Felis catus'') is a domestic Domestic may refer to: In the home * Anything relating to the human home A home, or domicile, is a space used as a permanent or semi-permanent residence for an individual, group or family ...

cat
s and dogs are a factor in more than 86,000 falls each year. It has been estimated that around 2% of dog-related injuries treated in U.K. 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. ''Toxocara canis'' (dog
roundworm The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the valu ...

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. Untreated toxocariasis can cause retinal damage and decreased vision. Dog feces can also contain
hookworm Hookworms are intestinal, blood-feeding, parasitic roundworms that cause types of infection known as helminthiases. Hookworm infection is found in many parts of the world, and is common in areas with poor access to adequate water, sanitation, ...
s that cause cutaneous larva migrans in humans.


Health benefits

Dogs suffer from the same common disorders as humans; these include cancer, diabetes, heart disease and neurologic disorders. Their pathology is similar to humans, as is their response to treatment and their outcomes. Researchers are identifying the genes associated with dog diseases similar to human disorders, but lack mouse models to find cures for both dogs and humans. The genes involved in canine obsessive-compulsive disorders led to the detection of four genes in humans' related pathways. The scientific evidence is mixed as to whether a dog's companionship can enhance human physical health and psychological well-being. Studies suggesting that there are benefits to physical health and psychological well-being have been criticized for being poorly controlled. It found that "the 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. 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." In one study, new guardians reported a highly significant reduction in minor health problems during the first month following pet acquisition. This effect was sustained in those with dogs through to the end of the study. People with pet dogs took considerably more physical exercise than those with cats and those without pets. The results provide evidence that keeping pets may have positive effects on human health and behavior and that for guardians of dogs, these effects are relatively long-term. Pet guardianship has also been associated with increased coronary artery disease survival. Human guardians are significantly less likely to die within one year of an acute myocardial infarction than those who did not own dogs. The health benefits of dogs can result from contact with dogs in general, not solely from having dogs as pets. For example, when in a pet dog's presence, people show reductions in cardiovascular, behavioral and psychological indicators of anxiety. Other health benefits are gained from exposure to immune-stimulating microorganisms, which can protect against allergies and autoimmune diseases according to the hygiene hypothesis. The benefits of contact with a dog also include social support, as dogs cannot only provide companionship and social support themselves but also act as facilitators of social interactions between humans. One study indicated that wheelchair users experience more positive social interactions with strangers when accompanied by a dog than when they are not. In 2015, a study found that pet owners were significantly more likely to get to know people in their neighborhood than non-pet owners. 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. 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. 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 with those not in an animal-assisted program.


Cultural importance

Dogs were depicted to symbolize Guide, guidance, protection, loyalty, fidelity, faithfulness, alertness, and love. In ancient Mesopotamia, from the Babylonia, Old Babylonian period until the Neo-Babylonian Empire, Neo-Babylonian, dogs were the symbol of Nintinugga, Ninisina, the goddess of healing and medicine, and her worshippers frequently dedicated small models of seated dogs to her. In the Neo-Assyrian Empire, Neo-Assyrian and Neo-Babylonian periods, dogs were used as emblems of magical protection. In China, Korea and Japan, dogs are viewed as kind protectors. In mythology, dogs often serve as pets or as watchdogs. Stories of dogs guarding the gates of the underworld recur throughout Indo-European mythologies and may originate from Proto-Indo-European religion. In Greek mythology, Cerberus is a three-headed, dragon-tailed watchdog who guards the gates of Hades. In Norse mythology, a bloody, four-eyed dog called Garmr guards Helheim. In Persian mythology, two four-eyed dogs guard the Chinvat Bridge. In Welsh mythology, Annwn is guarded by Cŵn Annwn. In Hindu mythology, Yama, the god of death, owns two watchdogs who have four eyes. They are said to watch over the gates of Naraka. In Christianity, dogs represent faithfulness. Within the Roman Catholic denomination specifically, the iconography of Saint Dominic includes a dog, after the hallow's mother dreamt of a dog springing from her womb and becoming pregnant shortly after that. As such, the Dominican Order (Ecclesiastical Latin: ''Domini canis'') means "dog of the Lord" or "hound of the Lord" (Ecclesiastical Latin: ''Domini canis''). In Christian folklore, a church grim often takes the form of a black dog to guard Christian churches and their churchyards from sacrilege. Jewish law does not prohibit keeping dogs and other pets. Jewish law requires Jews to feed dogs (and other animals that they own) before themselves and make arrangements for feeding them before obtaining them. The view on dogs in Islam is mixed, with some schools of thought viewing it as unclean, although Khaled Abou El Fadl states that this view is based on "pre-Islamic Arab mythology" and "a tradition to be falsely attributed to the Prophet." Therefore, Sunni Malaki and Hanafi jurists permit the trade of and keeping of dogs as pets.


Terminology

* ''Dog'' – the species (or subspecies) as a whole, also any male member of the same. * ''Bitch'' – any female member of the species (or subspecies). * ''Puppy'' or ''pup'' – a young member of the species (or subspecies) under 12 months old. * ''Sire'' – the male parent of a litter. * ''Dam'' – the female parent of a litter. * ''Litter (animal), Litter'' – all of the puppies resulting from a single whelping. * ''Whelping'' – the act of a bitch giving birth. * ''Whelps'' – puppies still dependent upon their dam.


See also

* Lists of dogs * Dog–cat relationship * Dognapping * Cynanthropy * Domesticated silver fox * Miller's Anatomy of the Dog * Portal:Dogs, Dogs portal * Portal:Mammals, Mammals portal


References


Bibliography

* * * * * * * * *


External links


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 th
dog genome
on Ensembl {{Authority control Dogs Wolves Scavengers Cosmopolitan species Animal models Extant Late Pleistocene first appearances Mammals described in 1758 Taxa named by Carl Linnaeus