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Fossil range: Late Pleistocene - Recent
Scientific classification
Domain: Eukaryota, Kingdom: Animalia, Phylum: Chordata, Class: Mammalia, Order: Carnivora
Family: Canidae, Genus: Canis, Species: C. lupus, Subspecies: C. l. familiaris, Trinomial name
Canis lupus familiaris
Dogs Portal
The dog (Canis lupus familiaris) is a domestic subspecies of the wolf, a mammal of the Canidae family of the order Carnivora. The term encompasses both feral and pet variants. It is also sometimes used to describe wild canids of other subspecies or species.
Over time, the dog has developed into hundreds of breeds with a great degree of variation. For example, heights at the withers range from just a few inches (such as the Chihuahua) to roughly three feet (such as the Irish Wolfhound); colors vary from white through grays (usually called blue) to black, and browns from light (tan) to dark ("red" or "chocolate") in a tremendous variation of patterns; and coats can be anything from very short to several centimeters long, from coarse hair to something akin to wool, straight or curly, or smooth.
Origins
Main article: Origin of the domestic dog
Some research appears to show that dogs were domesticated from wolves as recently as 15,000 years ago,[1] or perhaps as early as 100,000 years ago based upon recent genetic, fossil and DNA evidence.[2] Other research suggests that dogs have only been domesticated for a much shorter amount of time and were domesticated from populations of wild dogs, which had previously diverged from wolves.[3][4]
New evidence suggests that dogs were first domesticated in East Asia, possibly China,[5] 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.[5]
As humans migrated around the planet a variety of dog forms migrated with them. The agricultural revolution and subsequent urban revolution led to an increase in the dog population and a demand for specialization. These circumstances would provide the opportunity for selective breeding to create specialized working dogs and pets.
Human relationships
Dogs, like humans, are highly social animals and this similarity in their overall behavioral pattern accounts for their trainability, playfulness, and ability to fit into human households and social situations. This similarity has earned dogs a unique position in the realm of interspecies relationships.
The loyalty and devotion that dogs demonstrate as part of their natural instincts as pack animals closely mimics the human idea of love and friendship, leading many dog owners to view their pets as full-fledged family members. Conversely, dogs seem to view their human companions as members of their pack, and make few, if any, distinctions between their owners and fellow dogs. Dogs fill a variety of roles in human society and are often trained as working dogs. For dogs that do not have traditional jobs, a wide range of dog sports provide the opportunity to exhibit their natural skills. In many countries, the most common and perhaps most important role of dogs is as companions.
Dogs have lived with and worked with humans in so many roles that their loyalty has earned them the unique sobriquet "man's best friend".[6] However, some cultures consider dogs to be unclean. In some parts of the world, dogs are raised as livestock to produce dog meat for human consumption. In many places, consumption of dog meat is discouraged by social convention or cultural taboo.
Terminology
The English word dog, 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 (as in "the dog family"), 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.
The English word dog might derive from the Old English docga, 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, though referring to a specific breed in English, means "dog" in general in German and Dutch. Hound itself derives from the Proto-Indo-European *kwon-, which is the direct root of the Greek κυων (kuōn) and the indirect root of the Latin canis through the variant form *kani-.[7]
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
Many dogs can easily be trained to retrieve.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. Being highly adaptable animals themselves, dogs have learned to do a great number of very eclectic jobs as man has required over the generations. Dogs are employed in various roles across the globe, proving invaluable assets in areas such as search-and-rescue; law enforcement (including attack dogs, sniffer dogs and tracking dogs); guards for livestock, people or property; herding; Arctic exploration sled-pullers; guiding the blind and acting as a pair of ears for the deaf; assisting with hunting, and a great many other roles which they may be trained to assume. Dogs are descended from wolves, and are also pack animals, making them easier than other animals to train because dogs' instincts are to obey. Most dogs rarely have to deal with complex tasks and are unlikely to learn relatively complicated activities (such as opening doors) unaided. Some dogs (such as guide dogs for the visually impaired) are specially trained to recognize and avoid dangerous situations.
Evaluation of a dog's intelligence
The meaning of "intelligence" in general, not only in reference to dogs, is hard to define. Some tests measure problem-solving abilities and others test the ability to learn in comparison to others of the same age. Defining it for dogs is just as difficult. It is likely that dogs do not have the ability to premeditate an action to solve a problem. Some dogs may, however, have more drive to keep trying various things until they accidentally reach a solution and still others might have more ability to make the association between the "accident" and the result.[citation needed]
For example, the ability to learn quickly could be a sign of intelligence. Conversely it could be interpreted as a sign of blind subservience and a desire to please. In contrast, some dogs who do not learn very quickly may have other talents. An example is breeds that are not particularly interested in pleasing their owners, such as Siberian Huskies. Huskies are often fascinated with the myriad of possibilities for escaping from yards, catching small animals, and often figuring out on their own numerous inventive ways of doing both.
Assistance dogs are also required to be obedient at all times. This means they must learn a tremendous number of commands, understand how to act in a large variety of situations, and recognize threats to their human companion, some of which they might never before have encountered.
Many owners of livestock guardian breeds believe that breeds like the Great Pyrenees or the Kuvasz are not easily trained because their stubborn nature prevents them from seeing the point of such commands as “sit” or “down”. Hounds may also suffer from this type of ranking. In fact several rank in the bottom tier of "The Intelligence of Dogs" list (such as Beagles, Bloodhounds, and Basset Hounds).[citation needed] These dogs are bred to have more of a "pack" mentality with other dogs and less reliance on a master's direct commands. While they may not have the same kind of intelligence as a Border Collie, they were not bred to learn and obey commands quickly, but to think for themselves while trailing game.
Physical characteristics
Some dogs, like this Weimaraner, have their predatory instincts suppressed in order to better assist human hunters.See also: Dog health
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
Amazonian dogs, such as this one from Alto Amazonas, Peru are critical for indigenous peoples' hunting strategies, particularly in the rain forest.Dogs were thought to be dichromats and thus, by human standards, color blind.[8][9] It is now known that dogs can't see the color red very well.
Different breeds of dogs have different eye shapes and dimensions, and they also have different retina configurations.[10] Dogs with long noses have a "visual streak" which runs across the width of the retina and gives them a very wide field of excellent vision, while those with short noses have an "area centralis" -- a central patch with up to three times the density of nerve endings as the visual streak -- giving them detailed sight much more like a human's.
Some breeds, particularly the best sighthounds, have a field of vision up to 270° (compared to 180° for humans), although broad-headed breeds with short noses have a much narrower field of vision, as low as 180°.[8][9]
Hearing
This Collie/Saluki angles her ears to find the source of a sound.Dogs detect sounds as low as the 16 to 20Hz frequency range (compared to 20 to 70 Hz for humans) and above 45 kHz[11] (compared to 13 to 20 kHz for humans),[9] and in addition have a degree of ear mobility that helps them to rapidly pinpoint the exact location of a sound. Eighteen or more muscles can tilt, rotate and raise or lower a dog's ear. Additionally, a dog can identify a sound's location much faster than a human can, as well as hear sounds up to four times the distance that humans are able to. Those with more natural ear shapes, like those of wild canids like the fox, generally hear better than those with the floppier ears of many domesticated species.
Smell
Dogs have nearly 220 million smell-sensitive cells over an area about the size of a pocket handkerchief (compared to 5 million over an area the size of a postage stamp for humans). Some breeds have been selectively bred for excellence in detecting scents, even compared to their canine brethren. What information a dog actually detects when he is scenting is not perfectly understood; although once a matter of debate, it now seems to be well established that dogs can distinguish two different types of scents when trailing, an air scent from some person or thing that has recently passed by, as well as a ground scent that remains detectable for a much longer period. The characteristics and behavior of these two types of scent trail would seem, after some thought, to be quite different, the air scent being intermittent but perhaps less obscured by competing scents, whereas the ground scent would be relatively permanent with respect to careful and repetitive search by the dog, but would seem to be much more contaminated with other scents. In any event, it is established by those who train tracking dogs that it is impossible to teach the dog how to track any better than it does naturally; the object instead is to motivate it properly, and teach it to maintain focus on a single track and ignore any others that might otherwise seem of greater interest to an untrained dog. An intensive search for a scent, for instance searching a ship for contraband, can actually be very fatiguing for a dog, and the dog must be motivated to continue this hard work for a long period of time.
Working, utility and assistance dogs
There are several types of working dogs:
Assistance dogs which help the seeing and hearing-impaired. Others are trained to help those with epilepsy and psychiatric disorders, by detecting the onset of the condition so they can seek help. The typical assistance dog is a sociable breed such as a Labrador Retriever.
The detection dog, which is a dog trained to and works at using its senses (almost always the sense of smell) to detect substances such as explosives or illegal drugs.
Guard dogs trained to protect property. These are commonly Doberman Pinschers, German Shepherds and Rottweilers or mixes of these breeds.
Herding dogs trained to protect livestock in the range against predators. Sheepdogs are a common breed.
Hunting dogs that search for and retrieve game. Pointers and retrievers are typical hunting breeds.
Police dogs, typically German Shepherds, are trained to assist law enforcement officers.
Rescue dogs that search for missing humans. The archetypal breeds are the St. Bernard and the Bloodhound, although any dog with a good sense of smell can be trained to perform this task.
Therapy dogs, with friendly and gentle temperaments, trained to provide comfort and affection to hospitalized and institutionalized patients.
The war dog, used by the military to detect mines and enemy soldiers.
Show and sport (competition) dogs
Owners of dogs often enter them in competitions, whether show (breed conformation shows) or sports, including dog racing & dog sledding. The winners garner much prestige and prize money. These dogs are often bred specifically for competition, which may not be entirely beneficial for the breeds due to the magnification of hereditary defects.
Dog agility is a sport in which dogs complete a timed obstacle course.
Dogsled racing is a winter sport where a team of dogs, usually Huskies or Malamutes, pull a sled and driver (called a musher). The Iditarod Trail Sled Dog Race is perhaps the most famous of these races. Dog sledding is an ancient form of transportation and still a very effective way of moving freight across this type of terrain.
Dog racing, almost always Greyhounds, involves dogs racing at betting tracks in a sport not unlike horseracing, reaching speeds of 40 miles per hour. Elsewhere, Dachshunds are often raced, as a humourous sidelight in charity events.
Dog fighting and dog baiting are blood sports involving dogs. They are illegal in most jurisdictions, but are still occasionally performed underground.
The show dog, purebreds entered in conformation dog shows and evaluated by how closely they match the ideal characteristics of the breed. The Westminster Kennel Club Dog Show is one of the most famous of this type of competition.
Diet
At present, there is some debate as to whether domestic dogs should be classified as omnivores or carnivores, by diet. The classification in the Order Carnivora does not necessarily mean that a dog's diet must be restricted to meat; unlike an obligate carnivore, such as the cat family with its shorter small intestine, a dog is dependent on neither meat-specific protein nor a very high level of protein in order to fulfill its basic dietary requirements. Dogs are able to healthily digest a variety of foods including vegetables and grains, and in fact dogs can consume a large proportion of these in their diet. Wild canines not only eat available plants to obtain essential amino acids, but also obtain nutrients from vegetable matter from the stomach and intestinal contents of their herbivorous prey, which they usually consume. Domestic dogs can survive healthily on a reasonable and carefully designed vegetarian diet, particularly if eggs and milk products are included. Some sources suggest that a dog fed on a strict vegetarian diet may develop dilated cardiomyopathy since it lacks L-carnitine,[12] however, maintaining a balanced diet is also a factor since L-carnitine is found naturally in many nuts, seeds, beans, vegetables, fruits and whole grains. In the wild, dogs can survive on a vegetarian diet when animal prey is not available. However it has been noted, both by observation of extremely stressful conditions such as the Iditarod Trail Sled Dog Race and by scientific studies of similar conditions, that high-protein (approximately 40%) diets including meat help prevent damage to muscle tissue. (This research is also true for some other mammals.) This level of protein corresponds to the percentage of protein found in the wild dog's diet when prey is abundant; higher levels of protein seem to confer no added benefit.
Dogs frequently eat grass, which is a harmless activity. Explanations abound, but rationales such as that it neutralizes acid, or that eating grass might make the dog vomit, so dogs eat grass to remove unwanted substances from their stomachs, are at best educated guesses. Dogs do vomit more readily than humans, as part of their typical feeding behavior of gulping down food then regurgitating indigestible bones, fur, etc. This behavior is typical of pack feeding in the wild, where the most important thing is to get as much of the kill as possible before others consume it all. Individual domestic dogs, however, may be very "picky" eaters, in the absence of this evolutionary pressure.
Dangerous substances
Some foods commonly enjoyed by humans are dangerous to dogs, including chocolate (Theobromine poisoning), onions, grapes and raisins,[13] some types of gum, certain sweeteners[14] and Macadamia nuts. It is currently believed that the only dangerous substance in chocolate is cocoa, meaning that forms of chocolate without this compound, such as white chocolate may become re-evaluated for their safety in future.
The acute danger from grapes and raisins has been uncovered only since about 2000, and made public slowly since then. At present the cause is not known. Whatever the reason, since only small quantities are necessary to induce acute renal failure, dogs should not be fed grapes or raisins, and sultanas and currants should likely be withheld as well.
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 (Tylenol). 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.[15]
Amaryllis, daffodil, english ivy, iris, and tulip (especially the bulbs) 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.
Zinc toxicity, mostly in the form of the ingestion of US pennies minted after 1982, is commonly fatal in dogs where it causes a severe hemolytic anemia.[16]
Dogs will occasionally eat their own feces or the feces of other species if available, such as that of cats and horses. This is known as coprophagia, and may be indicative of boredom or hunger, although there is no definitive reason known. Owners of both cats and dogs may find that dogs treat the catbox as a snack bar. Such behavior should be discouraged, as it could lead to Toxoplasmosis.
Reproduction
General
In domestic dogs, sexual maturity (puberty) begins to happen around age 6 to 12 months for both males and females, although this can be delayed until up to two years old for some large breeds. Adolescence for most domestic dogs is around 12 to 15 months, beyond which they are for the most part more adult than puppy. As with other domesticated species, domestication has selectively bred for higher libido and earlier and more frequent breeding cycles in dogs, than in their wild ancestors.
Males
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Females
Females have a twice-yearly fertile period, known as 'seasons', during which her body prepares for pregnancy, and at the peak she will come "into heat", her fertile period, during which time she will be mentally and physically receptive to copulation. A female is able to become pregnant on her first heat; this is not normally considered advisable as she is mentally and physically still young in other ways.
As with most domesticated species, one of the first and strongest effects seen from selective breeding is selection for cooperation with the breeding process as directed by humans. In domestic dogs, one of the behaviors that is noted is the abolition of the pair bond seen in wild canines. The ability of female domestic dog to come into estrus at any time of the year and usually twice a year is also valued. The amount of time between cycles varies greatly among different dogs, but a particular dog's cycle tends to be consistent through her life. This is also called in season or in heat. Conversely, undomesticated canine species experience estrus once a year, typically in late winter.
Most female dogs come into season for the first time between 6 and 12 months, although some larger breeds delay until as late as 2 years. Like most mammals, the age that a bitch first comes into season is mostly a function of her current body weight as a proportion of her body weight when fully mature. The different rates of maturation are responsible for the menarche, not the chronological age. They then experience fertile seasons biannually until old age. Female dogs do not experience menopause, although their cycles will become irregular and fertility becomes unpredictable as the become older. Dogs over around 7 or 8 years are usually considered no longer appropriate for breeding, but can still remain fertile.
Copulation
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When copulating, a male canine initially mounts the female from behind, as with most tetrapods, a position known informally as doggy style. The female will hold her tail to the side and allow this if receptive. If unreceptive she may sit or lie down, snap, move away, or otherwise be uncooperative or not allow mating. The male will often move about as he tries to get a good purchase upon her, and whilst attempting penetration of his penis to the female's vulva. At this point, the penis is not erect, it is slender and held rigid by a small bone inside, known as the baculum.
When the male achieves penetration, he will often hold tighter and thrust faster, and it is at this point when he is mating that the male's penis expands. Canine reproduction is different from human sexual intercourse, because human males become erect first, and then enter the female; canine males enter first, then swell and become erect.
The male dog has a bulbus glandis, a spherical area of erectile tissue at the base of the penis, which traps the penis inside the female's vagina during copulation as it becomes engorged with blood. [1]
Once the penis is locked into the vagina by the bulbus glandis, the male will usually lift a leg and swing it over the female's back while turning around. The two stand with their hind ends touching and the penis locked inside the vagina while ejaculation occurs, decreasing leakage of semen from the vagina. After some time, typically 5 - 20 minutes (but sometimes longer), the bulbus glandis disengorges, allowing the mates to separate. Virgin dogs can become quite distressed at finding themselves unable to separate during their first copulation, and may try to pull away or run. Dog breeders' websites often suggest it is appropriate for those involved to help calm and settle the mating dogs once this stage is reached, if they show anxiety, through until eventual separation.
Note that similar canine mounting behavior (sometimes with pelvic thrusting) is also used by dominant canines of both sexes. Dominance mounting, with or without thrusting, should not be confused with copulatory mounting, in which the thrusting is short term until a "tie" is achieved.
Gestation and litters
A Catahoula Leopard mother nursing her litter of puppies.Dogs bear their litters roughly 9 weeks after fertilization, although the length of gestation can vary from 56 to 72 days. A general rule of thumb is that a mammal will produce half as many offspring as the number of teats on the mother. This rule is altered in domesticated animals since larger litters are often favored for economic reasons and in dogs, particularly, the great range of sizes and shapes plays a role in how many healthy puppies a female can carry. An average litter consists of about six puppies, though this number may vary widely based on the breed of dog. Toy dogs generally produce from one to four puppies in each litter, while much larger breeds may average as many as 12 pups in each litter. The number of puppies also varies with the mother's age and health, the father's sperm count, the timing of the breeding, and many other factors.
Some breeds have been developed to emphasize certain physical traits beyond the point at which they can safely bear litters on their own. For example, the Bulldog often requires artificial insemination and almost always requires cesarean section for giving birth. Since a mother can provide nutrients and care to only a limited number of offspring, humans must assist in the care and feeding when the litter exceeds approximately eight puppies.
Spaying and neutering
For more details on this topic, see Spaying and neutering.
The neutrality of this section is disputed.
Please see the discussion on the talk page.
Spaying (females only) and neutering (both genders but more usually males) refers to the sterilization of animals, usually by removal of the male's testicles or the female's ovaries and uterus, in order to eliminate the ability to procreate, and reduce sex drive. Neutering has also been known to reduce aggression in male dogs, but can occasionally increase aggression in female dogs.
Animal control agencies in the United States and the ASPCA advise that dogs not intended for further breeding should be spayed or neutered so that they do not have undesired puppies. In the less developed countries of Europe, spaying or neutering of dogs is less common, and owners are usually instead advised to keep their dogs on leash and under supervision to avoid unwanted matings; drugs are used to prevent pregnancy and abort unwanted litters.[citation needed]
Because of the overpopulation of dogs in some countries, puppies born to strays or as the result of accidental breedings often end up being killed in animal shelters. Spaying and neutering can also decrease the risk of hormone-driven diseases such as mammary cancer, as well as undesired hormone-driven behaviors. The hormonal changes involved with sterilization are likely to somewhat change the animal's personality, however, and some object to spaying and neutering as the sterilization could be carried out without the excision of organs.
Contrary to myth, it is not required for a female dog to either experience a heat cycle or have puppies before spaying, and likewise, a male dog does not need the experience of mating before neutering. Female dogs spayed before their first heat have a vastly lower incidence of mammary tumors than dogs which are spayed after their first heat or pregnancy (1% verses 22%). A female dog can become pregnant on her first heat cycle (which can take place as early as six months), and should be kept away from intact male dogs, including littermates, over the age of 4 months[citation needed].
Gender-preservative surgeries such as vasectomy and tubal ligation are possible, but do not appear to be popular due to the continuation of gender-specific behaviors and disease risks.
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.[17] 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 at the end of every episode, saying: "Help control the pet population. Have your pets spayed or neutered."
Dog health
Main article: Dog health
Further information: Category: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.[18]
Diseases
Infectious diseases commonly associated with dogs include rabies (hydrophobia), 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 (excluding many infections which are species specific) like hypothyroidism, cancer, dental disease, heart disease, etc.
Two serious medical conditions affecting dogs are pyometra, affecting unspayed females of all types and ages, and bloat, which affects the larger breeds or deep chested dogs. Both of these are acute conditions, and can kill rapidly; owners of dogs which may be at risk should learn about such conditions as part of good animal care.
Parasites
Common external parasites are various species of fleas, ticks, and mites. Internal parasites include hookworms, tapeworms, roundworms, and heartworms. See also CVBD (Canine Vector-Borne Diseases).
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 and old age
Main articles: Dog years, Aging in dogs
The typical lifespan of dogs varies considerably by breed. For example, many giant dog breeds (such as Great Danes) average only 7 or 8 years, while some small terrier breeds, or toy breeds might live as long as 20 or above. 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 years and 27 days, the breed of the dog was an Australian cattle dog and it lived in Virginia, USA, the date of death was in 1939. The oldest currently living dog is from Canberra, Australia and is now 27 years old. 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 regular exercise, treating its diseases, caring for its special needs and giving it love and comfort.
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