Encyclopedia
The
dog is a mammal in the order
Carnivora. Dogs were
domesticated from
wolves as recently as 15,000 years ago, or perhaps as early as 100,000 years ago based upon recent genetic
fossil and
DNA evidence . New evidence suggests that dogs were first domesticated in East Asia, possibly China , and the first peoples to enter North America took dogs with them from Asia. Genetic research has identified 14 ancient dog breeds, with the oldest being the
Chow Chow,
Shar Pei,
Akita Inu,
Shiba Inu and
Basenji. Because many of the 14 breeds are associated with China and Japan, the theory that the dog originated in Asia seems to be likely. Conversely, some cultures consider dogs to be
unclean. In some cultures, certain types of dogs are used as
food.
Terminology
The
English word , in common usage, refers to the domestic pet dog,
Canis lupus familiaris. The species was originally classified as
Canis familiaris by Linnaeus in 1758. In 1993, dogs were reclassified as a subspecies of the gray wolf,
Canis lupus, by the
Smithsonian Institution and the American Society of Mammalogists. "Dog" is sometimes used to refer collectively to any mammal belonging to the family
Canidae , such as wolves, foxes, and coyotes. Some members of the family have "dog" in their common names, such as the
African Wild Dog. The constellations
Canes Venatici,
Canis Major and Canis Minor are named from the
Latin word for "dog," for their perceived resemblance to dogs.
An alternative designation has also been presented, which is to name dog either
Canis lupus f. familiaris or
Canis familiaris L.. This terminology has been considered accurate by geologists and zooarcheologists for a while, since dogs would not be a subspecies of wolf if the above designation should be considered correct, but 450 subspieces of wolf. The designation was presented by a group of scientists in the article "The naming of Wild Animals and their Domestic Deriatives" in the Journal of Archeological Science # 31 in 2004.
The English word
dog derives from the Old English , a "powerful breed of canine". The French
dogue and Spanish
dogo as in
dogo Argentino are borrowings from English. The English word
hound is a cognate of the German
Hund and Dutch
hond, which applies to all breeds.
Hound itself, like Latin
canis and Greek ???? , derive ultimately from the Proto-Indo-European *kuon-.
In breeding circles, a male canine is referred to as a
dog, while a female canine is called a
bitch. Offspring are generally called
pups or
puppies until they are about a year old. A group of offspring is a
litter. The process of birth is
whelping. Many
terms are used for dogs that are not purebred.
Intelligence
Among dog lovers, dogs are generally valued for their intelligence, and both anecdotal evidence and
scientific research suggest that dogs have a reasonably high intelligence. This intelligence is expressed differently with different breeds and individuals, however. For example,
Border Collies are noted for their ability to learn commands, while other breeds may not be so motivated towards obedience, but instead show their cleverness in devising ways to steal food or escape from a yard. Dogs are descended from wolves, and are also pack animals, making them easier than other animals to train because dogs' instincts are to obey. But most dogs rarely have to deal with complex tasks and are unlikely to learn relatively complicated activities unaided. Some dogs are specially trained to recognize and avoid dangerous situations.
Physical characteristics
Modern
dog breeds show more variation in size, appearance, and behavior than any other domestic animal. Within the range of extremes, dogs generally share attributes with their wild ancestors, the
wolves. Dogs are
predators and
scavengers, possessing sharp teeth and strong jaws for attacking, holding, and tearing their food. Although selective breeding has changed the appearance of many breeds, all dogs retain basic traits from their distant ancestors. Like many other predatory mammals, the dog has powerful muscles, fused wristbones, a
cardiovascular system that supports both sprinting and endurance, and teeth for catching and tearing. Compared to the bone structure of the human foot, dogs technically walk on their toes.
Sight
Dogs were thought to be dichromats and thus, by human standards,
color blind. New research is now being explored that suggests that dogs may actually see some color, but not to the extent that humans do; color may serve as a subliminal signal helping to distinguish overlapping objects from each other, rather than a distinct feature that the dog can directly determine. It has also been suggested that dogs see in varieties of purple/violet and yellow shades. Because the lenses of dogs' eyes are flatter than humans', they cannot see as much detail; on the other hand, their eyes are more sensitive to light and motion than humans' eyes. Some breeds, particularly the best
sighthounds, have a field of vision up to 270° , although broad-headed breeds with their eyes set forward have a much narrower field of vision, as low as 180°. believes it may be an acute auto-immune response to plant-borne viruses in the same manner as
FIP in cats. Whatever the reason, since only small quantities are necessary to induce acute renal failure, dogs should not be fed grapes or raisins, and perhaps sultanas and currants should also be withheld.
Cooked
bones should
never be given to dogs, as the heat changes the chemical and physical properties so that they cannot be chewed properly, splintering into jagged shards, and resist digestion.
Human medications should not be given to a dog as a substitute for their regular medication as some can be especially
toxic, especially
paracetamol/acetaminophen .
Alcoholic beverages pose much of the same hazards to dogs as they do to humans.
Dogs may also find some poisons attractive, including
antifreeze,
snail bait,
insect bait, and
rodent poisons.
Antifreeze may be one of the most insidious of poisons to dogs because of its sweet taste and because a dog may walk upon or lie down upon a spill of it or its residue and then lick it off. Dogs must be kept strictly away from antifreeze and not allowed access to any place that has had a spill of it that has not been completely removed.
Plants such as
caladium,
dieffenbachia and
philodendron will cause throat irritations that will burn the throat going down as well as coming up.
Hops are particularly dangerous and even small quantities can lead to malignant hyperthermia.
Amaryllis,
daffodil,
english ivy, iris, and
tulip cause
gastric irritation and sometimes
central nervous system excitement followed by coma, and, in severe cases, even death.
Ingesting
foxglove,
lily of the valley, larkspur and
oleander can be life threatening because the
cardiovascular system is affected. Equally life threatening is the yew which affects the nervous system. If any of these plants are ingested, get the dog to a veterinarian immediately.
Many household cleaners such as
ammonia,
bleach, disinfectants, drain cleaner, soaps,
detergents, and other cleaners, mothballs and
matches are dangerous to dogs, as are cosmetics such as
deodorants,
hair coloring,
nail polish and remover,
home permanent lotion, and
suntan lotion.
Reproduction
Overpopulation
According to the Humane Society of the United States, 3-4 million dogs and cats are euthanized each year in the United States and many more are confined to cages in shelters because there are many more animals than there are homes. Spaying or neutering dogs helps keep overpopulation down. Local humane societies, SPCA's and other animal protection organizations urge people to spay or neuter their pets and to adopt animals from shelters instead of purchasing them. Several notable public figures have spoken out against animal over population, including
Bob Barker. On his
game show,
The Price is Right, Barker stressed the issue every episode by stating: "Help control the pet population. Have your pets spayed or neutered."
Dog health
Dogs are susceptible to various diseases, ailments, and poisons, some of which affect humans in the same way, others of which are unique to dogs. Dogs, like all mammals, are also susceptible to heat exhaustion when dealing with high levels of humidity and/or extreme temperatures.
Diseases
Infectious diseases commonly associated with dogs include
rabies , canine parvovirus, and canine distemper. Congenital diseases of dogs can include a wide range from hip dysplasia and medial patellar luxation to epilepsy and
pulmonic stenosis. Canines can get just about anything a human can get like hypothyroidism, cancer, dental disease, heart disease, etc.
Parasites
Common external parasites are various species of
fleas,
ticks, and
mites. Internal parasites include
hookworms,
tapeworms,
roundworms, and
heartworms.
Common physical disorders
Some breeds of dogs are also prone to certain genetic ailments, such as
hip dysplasia, luxating patellas,
cleft palate,
blindness, or deafness. Dogs are also susceptible to the same ailments that humans are, including diabetes,
epilepsy,
cancer, and arthritis.
Gastric torsion and
bloat is a dangerous problem in some large-chested breeds.
Lifespan
The typical lifespan of dogs varies considerably by breed. For example, many giant dog breeds average only 7 or 8 years, while some small terrier breeds might live as long as 20 years.The average lifespan for mixed-breed and midsize dogs is about 13 to 14 years. The longest-lived dog with reliable documentation died at 29 in 1939.
Although the lifespans of all living species are mostly uncontrollable, one can significantly extend a dog's life by feeding it the right kinds of foods, giving it exercise, visiting the vet frequently, caring for its special needs, and loving it.
Behavior
- For details, see .
Dogs are very social animals, but this varies on how a dog is treated by its owners and other people it may be around It is not uncommon for dogs to attack humans and other animals.
Ancestry and history of domestication
Molecular systematics indicate that the domestic dog descends from one or more populations of wild wolves . As reflected in the nomenclature, dogs are descended from the wolf and are able to interbreed with wolves.
The relationship between human and canine has deep roots.
Wolf remains have been found in association with
hominid remains dating from 400,000 years ago. Converging archaeological and genetic evidence indicate a time of
domestication in the late Upper Paleolithic close to the
Pleistocene/Holocene boundary, between 17,000 and 14,000 years ago.
Fossil bone morphologies and genetic analysis of current and ancient dog and wolf populations have not yet been able to conclusively determine whether all dogs descend from a single domestication event, or whether dogs were domesticated independently in more than one location. Domesticated dogs may have interbred with local populations of wild wolves on several occasions .
The earliest dog fossils, two
crania from
Russia and a mandible from
Germany, date from 13,000 to 17,000 years ago. Their likely ancestor is the large northern Holarctic wolf,
Canis lupus lupus. Remains of smaller dogs from Mesolithic cave deposits in the
Middle East, dated to around 12,000 years ago, have been interpreted as descendants of a lighter Southwest Asian wolf,
Canis lupus arabs.
Rock art and skeletal remains indicate that by 14,000 years ago, dogs were present from
North Africa across
Eurasia to
North America. Dog burials at the Mesolithic cemetery of Svaerdborg in Denmark suggest that in ancient Europe dogs were valued companions.
Genetic analyses have so far yielded divergent results. Vilà, Savolainen, and colleagues concluded that dogs split off from wolves between 75,000 and 135,000 years ago, while a subsequent analysis by Savolainen et al. indicated a "common origin from a single gene pool for all dog populations" between 40,000 and 15,000 years ago in
East Asia. Verginelli et al. , however, suggest both sets of dates must be reevaluated in light of recent findings showing that poorly calibrated molecular clocks have systematically overestimated the age of geologically recent events. On balance, and in agreement with the archaeological evidence, 15,000 years ago is the most likely time for the wolf-dog divergence.
Verginelli examined ancient
DNA evidence from five prehistoric Italian
canids carbon-dated to between 15,000 and 3,000 years old, 341 wolves from several populations worldwide, and 547 purebred dogs. Their results indicate multiple independent origins of dogs and/or of frequent interbreeding between early proto-dogs and wolves throughout a vast geographic range. The detailed history remains unexplored and until further evidence is available, the following section on wolf ancestors must be considered purely speculative.
Wolf ancestors
Although all wolves belong to the species
Canis lupus, there are many subspecies that had developed a distinctive appearance, social structure, and other traits. For example, the
Japanese Wolf and the
Eastern Timber Wolf possess different distinctive coloration, hunting and social structures.
The
Indian Wolf is thought to have contributed to the development of more breeds of dogs than other subspecies. Many of today's wild dogs, such as the
dingo and the
pariah dogs, are descended from this wolf.
The
Indian Wolf is also thought to have bred with descendants of the European wolf to create the Mastiffs and eventually leading to the development of such diverse breeds as the
Pug, the Saint Bernard, and the
Bloodhound. The
Tibetan Mastiff is an example of an ancient breed.
The
European wolf, in turn, may have contributed many of its attributes to the
Spitz dog types, most
terriers, and many of today's
sheepdogs. The Chinese wolf is probably ancestor to the
Pekingese and toy
spaniels, although it is also probable that descendants of the Chinese and European wolves encountered each other over the millennia, contributing to many of the oriental
toy breeds.
The
Eastern Timber Wolf is a direct ancestor to most, if not all, of the North American northern
sled dog types. This interbreeding still occurs with dogs living in the
Arctic region, where the attributes of the wolf that enable survival in a hostile environment are valued by humans. Additionally, unintentional crossbreeding occurs simply because dogs and wolves live in the same environment. The general
reproductive isolation which is required to define dogs and wolves as separate species is purely a result of lack of opportunity, stemming from a general mutual unfamiliarity, suspicion, mistrust, and fear.
The phenotypic characteristics that distinguish a wolf from a dog are tenuous. Wolves typically have a "brush tail" and erect ears. While some dog breeds possess one of these characteristics, they rarely possess both.
Speed of domestication
Current research indicates that domestication, or the attributes of a domesticated animal, can occur much more quickly than previously believed. Domestication of a wild dog may occur within one or two human generations with deliberate selective breeding. It is also now generally believed that initial domestication was through mutual desire. Wild canines who scavenged around human habitations received more food than their more skittish or fearful counterparts. Canines who attacked people or their children were likely killed or driven away, while those more friendly animals survived. Canines would have been beneficial by chasing away other
vermin or
scavengers. With their sharp senses, they would also be valuable as an alarm against marauding predators. The relationship is theorized to have developed in this way.
Dog meat for human consumption
Main article: Dog meatIn a number of countries around the world, apart from being kept as pets, certain breeds of dogs are slaughtered as a source of meat and specifically raised on farms for that purpose. In countries where dogs are particularly popular as household pets, the use of dogs as a source of food is often considered a taboo and abhorrent cultural practice, although there are exceptions such as
Vietnam where dogs are popular as pets and as meat.
Dog Abuse
Cruelty to dogs refers to treatment which causes unacceptable suffering or harm. What qualifies as unacceptable suffering varies depending on the country and its culture.
Famous dogs
The long shared history of dogs and humans has resulted in many individual dogs achieving fame or notoriety, and many fictional dogs have been created for literature, cinema, and elsewhere.
Dog breeds
There are numerous
dog breeds, with
over 800 being recognized by various kennel clubs worldwide. As all dog breeds have been derived from mixed-breed dog populations, the term "purebred" has meaning only with respect to a certain number of generations. Many dogs, especially outside the United States and Western Europe, belong to no recognized breed.
A few basic have evolved gradually during the domesticated dog's relationship with man over the last 10,000 or more years, but most modern breeds are of relatively recent derivation. Many of these are the product of a deliberate process of
artificial selection. Because of this, some breeds are highly specialized, and there is extraordinary morphological diversity across different breeds. Despite these differences, dogs are able to distinguish dogs from other kinds of animal.
The definition of a dog breed is a matter of some controversy. Depending on the size of the original founding population, closed gene pool breeds can have problems with inbreeding, specifically due to
founder effect. Dog breeders are increasingly aware of the importance of population genetics and of maintaining diverse gene pools. Health testing and new DNA tests can help avoid problems, by providing a replacement for natural selection. Without selection, inbreeding and closed gene pools can increase the risk of severe health or behavioural problems. Some organizations define a breed more loosely, such that an individual may be considered of one breed as long as 75% of its parentage is of that breed. These considerations affect both pets and the show dogs entered in
dog shows. Even prize-winning purebred dogs sometimes possess crippling genetic defects due to founder effect or inbreeding. These problems are not limited to purebred dogs and can affect mixed-breed populations. The behavior and appearance of a dog of a particular breed can be predicted fairly accurately, while mixed-breed dogs show a broader range of innovative appearance and behavior.
In February 2004, the Canine Studies Institute in
Aurora, Ohio, arranged recognized breeds of dogs into ten categories.
Mixed-breed dogs or Mongrels are dogs that do not belong to specific breeds, being mixtures of two or more in variant percentages. Mixed breeds, or dogs with no purebred ancestry, are not inherently "better" or "worse" than purebred dogs as companions, pets,
working dogs, or competitors in
dog sports. Sometimes mixed-breed dogs are deliberately bred, for example, the Cockapoo, a mixture of Cocker Spaniel and Miniature
Poodle. Such deliberate crosses may display
hybrid vigor and other desirable traits, but can also lack one or more of the desired traits of their parents, such as temperament or a particular color or coat. However, without genetic testing of the parents, the crosses can sometimes end up inheriting genetic defects that occur in both parental breeds. Deliberately crossing two or more breeds is also a manner of establishing new breeds.
Neoteny in the rapid evolution of diverse dog breeds
This rapid evolution of dogs from wolves is an example of neoteny or paedomorphism. As with many species, the young wolves are more social and less dominant than adults; therefore, the selection for these characteristics, whether deliberate or inadvertent, is more likely to result in a simple retention of juvenile characteristics into adulthood than to generate a complex of independent new changes in behavior. This paedomorphic selection naturally results in a retention of juvenile physical characteristics as well. Compared to wolves, many adult dog breeds retain such juvenile characteristics as soft fuzzy fur, round torsos, large heads and eyes, ears that hang down rather than stand erect, etc.; characteristics which are shared by most juvenile mammals, and therefore generally elicit some degree of protective and nurturing behavior cross-species from most adult mammals, including humans, who term such characteristics "cute" or "appealing".
The example of canine neoteny goes even further, in that the various breeds are differently neotenized according to the type of behavior that was selected.
- Livestock guardian dogs retain the most juvenile characteristics: they stay close to home with their foster "litter" , rather than going out hunting, they have almost no predatory behavior , they respond to perceived threats with a lot of vocalization and attempts to alert and engage the dominant individuals in their "pack" whenever possible, engaging in actual combat only as a last resort. In addition, they retain very juvenile physical characteristics such as round bodies and heads, soft coats, ears that hang down, and so on, which do not elicit fear responses from the sheep in the way that an appearance similar to that of an adult wolf would. .
- Gun dog breeds used in hunting—that is, pointers, setters, spaniels, and retrievers—have an intermediate degree of paedomorphism; they are at the point where they share in the pack's hunting behavior, but are still in a junior role, not participating in the actual attack. They identify potential prey and freeze into immobility, for instance, but refrain from then stalking the prey as an adult predator would do next; this results in the "pointing" behavior for which such dogs are bred. Similarly, they seize dead or wounded prey and bring it back to the "pack", even though they did not attack it themselves, that is, "retrieving" behavior. Their physical characteristics are closer to that of the mature wild canine than the sheepdog breeds, but they typically do not have erect ears, etc.
- Scenthounds maintain an intermediate body type and behavior pattern that causes them to actually pursue prey by tracking their scent, but tend to refrain from actual individual attacks in favor of vocally summoning the pack leaders to do the job. They often have a characteristic vocalization called a bay. Some examples are the Beagle, Bloodhound, Basset Hound, Coonhound, Dachshund, Fox Hound, Otter Hound, and Harrier.
- Sighthounds, who pursue and attack perceived prey on sight, maintain the mature canine size and some features, such as narrow chest and lean bodies, but have largely lost the erect ears of the wolf and thick double layered coats. Some examples are the Afghan, Borzoi, Saluki, Sloughi, Pharaoh Hound, Azawakh, Whippet, and Greyhound.
- Mastiff-types are large dogs, both tall and massive with barrel-like chests, large bones, and thick skulls. They have traditionally been bred for war, protection, and guardian work.
- Bulldog
| name = Bulldog
...
-types are medium sized dogs bred for combat against both wild and domesticated animals. These dogs have a massive, square skull and large bones with an extremely muscular build and broad shoulders.
- Terriers similarly have adult aggressive behavior, famously coupled with a lack of juvenile submission, and display correspondingly adult physical features such as erect ears, although many breeds have also been selected for size and sometimes dwarfed legs to enable them to pursue prey in their burrows.
The least paedomorphic behavior pattern may be that of the
basenji, bred in
Africa to hunt alongside humans almost on a peer basis; this breed is often described as highly independent, neither needing nor appreciating a great deal of human attention or nurturing, often described as "catlike" in its behavior. It too has the body plan of an adult canine predator.
Of course, dogs in general possess a significant ability to modify their behavior according to experience, including adapting to the behavior of their "pack leaders"—again, humans. This allows them to be trained to behave in a way that is not specifically the most natural to their breed; nevertheless, the accumulated experience of thousands of years shows that some combinations of nature and nurture are quite daunting, for instance, training
whippets to guard flocks of sheep.
Breed popularity
Breed popularity varies widely over time and in different parts of the world and different segments of the population. Counting by AKC registration , the
Labrador Retriever has been the United States's most commonly registered breed of dog since 1991. However, even within parts of the United States, popularity varies; for example, in 2005 the most-registered breed in New York City was the
Poodle; the
Yorkshire Terrier was the second-most-registered breed in
Houston but didn't even make the top ten in
Honolulu. However, animal shelters in many parts of the United States report that the most-commonly available dog for adoption is the
American Pit Bull Terrier or pit bull-type mixes, making up as much as 20% of dogs available for adoption, none of which would be registered with the AKC. Two decades ago, in 1983, the AKC's top two registered breeds were the
American Cocker Spaniel and the
Poodle.
In Britain, The Kennel Club reports that the most-registered breed from at least 1999 to 2005 was the Labrador Retriever. It rounds out the top three for 1999 to 2005 with the
German Shepherd Dog, also popular in the States, and the
English Cocker Spaniel, which is no longer even in the top ten in the States.
See also
References
Further reading
- Abrantes, Roger . Dogs Home Alone. Wakan Tanka, 46 pages. ISBN 0-9660484-2-3 .
- A&E Television Networks . Big Dogs, Little Dogs: The companion volume to the A&E special presentation, A Lookout Book, GT Publishing. ISBN 1-57719-353-9 .
- Alderton, David . The Dog, Chartwell Books. ISBN 0-89009-786-0.
- Brewer, Douglas J. Dogs in Antiquity: Anubis to Cerberus: The Origins of the Domestic Dog, Aris & Phillips ISBN 0-85668-704-9
- Coppinger, Raymond and Lorna Coppinger . Dogs: A New Understanding of Canine Origin, Behavior and Evolution, University of Chicago Press ISBN 0-226-11563-1
- Cunliffe, Juliette . The Encyclopedia of Dog Breeds. Parragon Publishing. ISBN 0-7525-8276-3.
- Derr, Mark . Dog's Best Friend: Annals of the Dog-Human Relationship. University of Chicago Press. ISBN 0-226-14280-9
- Donaldson, Jean . The Culture Clash. James & Kenneth Publishers. ISBN 1-888047-05-4 .
- Fogle, Bruce, DVM . The New Encyclopedia of the Dog. Doring Kindersley . ISBN 0-7894-6130-7.
- Grenier, Roger . The Difficulty of Being a Dog. University of Chicago Press. ISBN 0-226-30828-6
- Milani, Myrna M. . The Body Language and Emotion of Dogs: A practical guide to the Physical and Behavioral Displays Owners and Dogs Exchange and How to Use Them to Create a Lasting Bond, William Morrow, 283 pages. ISBN 0-688-12841-6 .
- Pfaffenberger, Clare . New Knowledge of Dog Behavior. Wiley, ISBN 0-87605-704-0 ; Dogwise Publications, 2001, 208 pages, ISBN 1-929242-04-2 .
- Savolainen, P. et al. . Genetic Evidence for an East Asian Origin of Domestic Dogs. Science 298. 5598: 1610–1613.
- Shook, Larry . "Breeders Can Hazardous to Health", The Puppy Report: How to Select a Healthy, Happy Dog, Chapter Two, pp. 13–34. Ballantine, 130 pages, ISBN 0-345-38439-3 ; Globe Pequot, 1992, ISBN 1-55821-140-3 .
- Shook, Larry . The Puppy Report: How to Select a Healthy, Happy Dog, Chapter Four, "Hereditary Problems in Purebred Dogs", pp. 57–72. Ballantine, 130 pages, ISBN 0-345-38439-3 ; Globe Pequot, 1992, ISBN 1-55821-140-3 .
- Thomas, Elizabeth Marshall . The Hidden Life of Dogs , A Peter Davison Book, Houghton Mifflin. ISBN 0-395-66958-8.
- Verginelli, F. et al. . Mitochondrial DNA from Prehistoric Canids Highlights Relationships Between Dogs and South-East European Wolves. Mol. Biol. Evol. 22: 2541–2551.
- Vilà, C. et al. . Science 276:1687–1689.
- Small animal internal medicine, RW Nelson, Couto page 107
External links
