The following are given passages.
Passage 1:
Police dog
A police dog is a dog that is trained to assist police and other law enforcement officers, search and rescue, or the military. Their duties may include searching for drugs and explosives, locating missing people, finding crime scene evidence, protecting officers and other people, and attacking suspects who flee from officers. The breeds most commonly used by law enforcement are the German Shepherd, Belgian Malinois, Bloodhound, Dutch Shepherd, and Labrador Retriever. In recent years, the Belgian Malinois has become the leading choice for police and military work due to their intense drive, focus, agility, and smaller size, though German Shepherds remain the breed most associated with law enforcement.Police dogs are used on a federal and local level for law enforcement purposes in many parts of the world. They are often assigned to a K-9 Unit with a specific handler, and must remember several verbal cues and hand gestures. Initial training for a police dog typically takes between eight months and a year, depending on where and how they are trained, and for what purpose. Police dogs often regularly take training programs with their assigned handler to reinforce their training. In many countries, intentionally injuring or killing a police dog is a criminal offense.In some English-speaking countries, police dog units are referred to as K-9 or K9, which is a homophone of the word canine.

History
Early history
Dogs have been used in law enforcement since the Middle Ages. Wealth and money was then tithed in the villages for the upkeep of the parish constable's bloodhounds that were used for hunting down outlaws. The first recorded use of police dogs were in the early 14th century in St. Malo, France, where dogs were used to guard docks and piers. By the late 14th century, bloodhounds were used in Scotland, known as "Slough dogs" – the word "Sleuth", (meaning detective) was derived from this. Between the 12th and 20th centuries, police dogs on the British Isles and European continent were primarily used for their tracking abilities.The rapid urbanization of England and France in the 19th century increased public concern regarding growing lawlessness. In London, the existing law enforcement, the Bow Street Runners, struggled to contain the crime on their own, and as a result, private associations were formed to help combat crime. Night watchmen were employed to guard premises, and were provided with firearms and dogs to protect themselves from criminals.

Modern era
One of the first attempts to use dogs in policing was in 1889 by the Commissioner of the Metropolitan Police of London, Sir Charles Warren. Warren's repeated failures at identifying and apprehending the serial killer Jack the Ripper had earned him much vilification from the press, including being denounced for not using bloodhounds to track the killer. He soon had two bloodhounds trained for the performance of a simple tracking test from the scene of another of the killer's crimes. The results were far from satisfactory, with one of the hounds biting the Commissioner and both dogs later running off, requiring a police search to find them.It was in Continental Europe that dogs were first used on a large scale. Police in Paris began using dogs against roaming criminal gangs at night, but it was the police department in Ghent, Belgium that introduced the first organized police dog service program in 1899. These methods soon spread to Austria-Hungary and Germany; in the latter the first scientific developments in the field took place with experiments in dog breeding and training. The German police selected the German Shepherd Dog as the ideal breed for police work and opened up the first dog training school in 1920 in Greenheide. In later years, many Belgian Malinois dogs were added to the unit. The dogs were systematically trained in obedience to their officers and tracking and attacking criminals. 
In Britain, the North Eastern Railway Police were among the first to use police dogs in 1908 to put a stop to theft from the docks in Hull. By 1910, railway police forces were experimenting with other breeds such as Belgian Malinois, Labrador Retrievers, and German shepherds.

Training
Popular dog breeds used by law enforcement include the Airedale terrier, Akita, Groenendael, Malinois dog, Bernese Mountain Dog, Bloodhound, Border Collie, Boxer, Bouvier des Flandres, Croatian Sheepdog, Doberman Pinscher, German Shepherd, German Shorthaired Pointer, Golden Retriever, Labrador Retriever, Rottweiler and English Springer Spaniel.Training of police dogs is a very lengthy process since it begins with the training of the canine handler. The canine handlers go through a long process of training to ensure that they will train the dog to the best of its ability. First, the canine handler has to complete the requisite police academy training and one to two years of patrol experience before becoming eligible to transfer to a specialty canine unit. This is because the experience as an officer allows prospective canine officers to gain valuable experience in law enforcement. However, having dog knowledge and training outside of the police academy is considered to be an asset, this could be dog obedience, crowd control, communicating effectively with animals and being approachable and personable since having a dog will draw attention from surrounding citizens.
For a dog to be considered for a police department, it must first pass a basic obedience training course. They must be able to obey the commands of their handler without hesitation. This allows the officer to have complete control over how much force the dog should use against a suspect. Dogs trained in Europe are usually given commands in the country's native language. Dogs are initially trained with this language for basic behavior, so, it is easier for the officer to learn new words/commands, rather than retraining the dog to new commands. This is contrary to the popular belief that police dogs are trained in a different language so that a suspect cannot command the dog against the officer.Dogs used in law enforcement are trained to either be "single purpose" or "dual purpose". Single-purpose dogs are used primarily for backup, personal protection, and tracking. Dual-purpose dogs, however, are more typical. Dual-purpose dogs do everything that single-purpose dogs do, and also detect either explosives or narcotics. Dogs can only be trained for one or the other because the dog cannot communicate to the officer if it found explosives or narcotics. When a narcotics dog in the United States indicates to the officer that it found something, the officer has probable cause to search whatever the dog alerted on (i.e. bag or vehicle) without a warrant, in most states.In suspect apprehension, having a loud barking dog is helpful and can result in suspects surrendering without delay.

Specialization
Police dogs can be specialized to perform in specific areas.

Apprehension and attack dogs – This dog is used to locate, apprehend, and sometimes subdue suspects.
Detection dogs – Trained to detect explosives or drugs such as marijuana, heroin, cocaine, crack cocaine, or methamphetamines. Some dogs are specifically trained to detect firearms and ammunition.
Dual purpose dog – Also known as a patrol dog, these dogs are trained and skilled in tracking, handler protection, off-leash obedience, criminal apprehension, and article, area and building search.
Search and rescue dogs (SAR) – This dog is used to locate suspects or find missing people or objects. Belgian Malinois, German Shepherds, Golden Retrievers, Labrador Retrievers, and Bloodhounds can all be used.

Retirement
Police dogs are retired if they become injured to an extent where they will not recover completely, pregnant or raising puppies, or are too old or sick to continue working. Since many dogs are raised in working environments for the first year of their life and retired before they become unable to perform, the working life of a dog is 6–9 years.However, when police dogs retire in some countries they may have the chance to receive a pension plan for their contribution to policing. In 2013, a pension scheme for police dogs in Nottinghamshire, England was introduced, wherein the police force offered £805 over the span of three years to cover any additional medical costs; the dogs were also allowed to be adopted by their original handler.In many countries, police dogs killed in the line of duty receive the same honors as their human partners.

Accusations of brutality and racial partiality
A 2020 investigation coordinated by the Marshall Project found evidence of widespread deployment of police dogs in the U.S. as disproportionate force and disproportionately against people of color. A series of 13 linked reports found more than 150 cases from 2015 to 2020 of K-9 officers improperly using dogs as weapons to catch, bite, and injure people. The rate of police K-9 bites in Baton Rouge, Louisiana, a majority-Black city of 220,000 residents, averages more than double that of the next-ranked city, Indianapolis, and nearly one-third of the police dog bites are inflicted on teenage men, most of whom are Black. Medical researchers found that police dog attacks are "more like shark attacks than nips from a family pet” due to the aggressive training police dogs undergo. Many people bitten were not violent and were not suspected of crimes. Police officers are often shielded from liability, and federal civil rights laws don’t typically cover bystanders who are bitten by mistake. Even when victims can bring cases, lawyers say they struggle because jurors tend to love police dogs.

Usage by country and region
Australia
The Australian Federal Police employ "general purpose" police dogs, whose duties include searching for missing persons, suspect apprehension, and keeping the peace. The Australian Federal Police also employ police dogs trained for specialized purposes, such as detecting firearms, explosives, illegal narcotics, and currency. The Australian Border Force also utilizes detector dogs to search for concealed people or illegal products at border checkpoints.

Bangladesh
Border Guards Bangladesh, Rapid Action Battalion and the Dhaka Metropolitan Police maintain several dog squads to assist in anti-narcotic and anti-bombing campaigns.

Belgium
The Belgian Canine Support Group is part of the country's federal police. It has 35 dog teams, most of which are Belgian Malinois. Some dogs are trained to detect drugs, human remains, hormones or fire accelerants. About a third are tracker dogs trained to find or identify living people. These teams are often deployed to earthquake areas to locate people trapped in collapsed buildings.  The federal police's explosive detector dogs are attached to the Federal Police Special Units.

Canada
Canadians started using police dogs occasionally in 1908. However, they used privately owned dogs until 1935 when the Royal Canadian Mounted Police (RCMP) saw the value of police dogs and created the first team in 1937. By the 1950s, the RCMP had German Shepherds, Schnauzers, and Doberman Pinschers in service.Many Canadian municipalities use dog squads as a means of tracking suspects. Most municipalities in Canada employ the bite and hold technique rather than the bark and hold technique meaning once the dog is deployed, it bites the suspect until the dog handler commands it to release. This often results in serious puncture wounds and is traumatic for suspects. A dog has the legal status of property in Canada. As such, developing case law is moving towards absolute liability for the handlers of animals deliberately released to intentionally maim suspects. The dog is effectively a weapon.
In 2010, an Alberta Court of Queen's Bench judge stayed criminal charges against Kirk Steele, a man who was near-fatally shot by a police officer while he stabbed the officer's police dog. The judge found that the shooting was cruel and unusual treatment and excessive force.Police require reasonable suspicion they will recover evidence in order to use a dog to sniff a person or their possessions in public. This is because using a dog to detect scents is considered a search. The main exemption to that rule are the dogs of the Canada Border Services Agency who are allowed to make searches without warrants under s.98 of the Customs Act.
In 2017, it was reported that the Canadian forces had approximately 170 RCMP dog teams across Canada, and was continuing to grow as more and more Canadian municipalities saw the value of police dogs.

Denmark
There are a total of 240 active police dogs in Denmark, each of which are ranked in one of three groups: Group 1, Group 2 and Group 3. Dogs in Group 1 are very experienced, and highly trained. Group 1 dogs are typically within the age range of four to eight years old and are used for patrolling, rescue, searching for biological evidence and major crime investigations. Group 2 dogs are employed for the same tasks as members of Group 1, but they do not participate in major crime investigations or searching for biological evidence. Group 3 is the beginner rank for police dogs, and are only employed for patrol operations.

Hong Kong
The Police Dog Unit (PDU; Chinese: 警犬隊) was established in 1949 and is a specialist force of the Hong Kong Police under the direct command of the Special Operations Bureau. Their roles are crowd control, search and rescue, and poison and explosive detection. In addition, the PDU works in collaboration with other departments for anti-crime operations.

Netherlands
The Dutch  Police Dog Brigade is part of the national police corps national unit, and supports other units with specially trained dogs. The  dogs are trained to recognize a single specific scent. They specialize in identifying scents (identifying the scent shared by an object and a person), narcotics, explosives and firearms, detecting human remains, and locating drowning people and fire accelerants.
The 10 regional units also have dog brigades of their own. For example, the canine unit of the regional police East netherlands.

India
In India, the National Security Guard inducted the Belgian Malinois into its K-9 Unit, Border Security Force, and Central Reserve Police Force use Rajapalayam as guard dogs to support the Force on the borders of Kashmir. 
For regional security, the Delhi Police has recruited many of the city's street dogs to be trained for security purposes. The Bengal Police uses German Shepherds, Labrador Retrievers, and the Indian pariah dog in its bomb-sniffing squad.

Israel
Israel utilizes canine units for border patrols to track illegal persons or objects that pose a threat. Police dogs serve in the Israel Police and Israel Prison Service.

Italy
All the law enforcement in Italy (Carabinieri, Polizia di Stato and Guardia di Finanza) have in service many patrol dogs for Public Order, Anti-Drug, Anti-explosive, Search and Rescue. The first train centers for police dogs in Italy were established after World War I and in 1924, Italy purchased German Shepherds from Germany for border patrol operations in the Alps. The Carabinieri Kennel Club was formed in 1957 to produce police dogs and train handlers in Italy. German and Belgian shepherds are used for multiple purposes, Labradors for drug, weapons and explosive surveillance and Rottweilers serve for protection.

Japan
Japan is one of the few east Asian countries that have dogs serving in law enforcement as others dislike dogs due to cultural norms. Between the 16th and 19th centuries, samurai had Akita service companions that would defend samurai while they slept at night. In modern times, the German shepherd is the common police dog of the Tokyo Metropolitan Police Department.

Kenya
Police dogs began their service in Kenya in 1948 as part of the Kenya Police Criminal Investigation Department of the Kenya Police. Since the 1950s, the main police dog in service is the German shepherd, with Labradors, Rottweilers and English Springer Spaniels being used for specialized purposes. Since the 2000s, the Kenya Police has increased the breeding and adoption of police dogs with the long-term goal of having canines serving in each police station of Kenya.

Nepal
The Nepal Police first established a canine unit in 1975 due to increased crime rates and to help with investigations. Since then, police dogs are in service throughout various regions of Nepal and have been present at the Tribhuwan International Airport since 2009.

Pakistan
Pakistan Customs uses a K-9 unit for anti-smuggling operations. Pakistan's Sindh Police also have a specialized K-9 unit.

Peru
Peru recruits various canine units for various governmental, military and police operations. The National Service of Agrarian Health (SENASA) of the Ministry of Agriculture and Irrigation has the Canine Brigade of Plant Health that detects plants that may violate phytosanitary trade practices and to prevent the contraband importation of pests in plants and fruit. The brigade is present at Jorge Chávez International Airport and in Peruvian territory.For the National Police of Peru, they prefer the German Shepherd, Belgian Shepherd Malinois, Beagle, Weimaraner, Golden Retriever and Labrador Retriever breeds for their service and accept donations of dogs between the ages of 12 and 24 months. The National Police use canine units for drug surveillance in the country's main airport, Jorge Chávez International Airport, with the force receiving canine training from United States Customs and Border Protection.The Peruvian Army has canine units trained for search and rescue as well as disaster situations. During the COVID-19 pandemic in Peru, a limitation of gatherings and curfew was enforced with the assistance of canine units that served for law enforcement.

Russia
Police dogs have been used in Russia since 1909 in Saint Petersburg. Attack dogs are used commonly by police and are muzzled at all times unless ordered to apprehend a suspect. Police dogs have also been used to track fugitives, which has remained common in most Soviet Union Successor States.

Sweden
The Swedish Police Authority currently deploys around 400 police canines. There is however no requirement for the dogs to be purebred, as long as they meet mental and physical requirements set by the police. Dogs aged 18–48 months are eligible to take admission tests for the K9 training. The police dogs live with their operators, and after retirement at age 8–10 the operator often assumes the ownership of the dog.

United Kingdom
Police forces across the country, as well as the RAF Police, employ dogs and handlers and dog training schools are available to cater for the ever-increasing number of dogs being used. The use of police dogs became popular in the 1930s when Scotland Yard officially added dogs to its police force.There are over 2,500 police dogs employed amongst the various police forces in the UK, with the Belgian Malinois as the most popular breed for general purpose work. In 2008, a Belgian Malinois female handled by PC Graham Clarke won the National Police Dog Trials with the highest score ever recorded.
All British police dogs, irrespective of the discipline they are trained in, must be licensed to work operationally. To obtain the licence they have to pass a test at the completion of their training, and then again every year until they retire, which is usually at about the age of 8. The standards required to become operational are laid down by the Association of Chief Police Officers (ACPO) sub-committee on police dogs and are reviewed on a regular basis to ensure that training and licensing reflects the most appropriate methods and standards.

United States
Police dogs are in widespread use across the United States. Police dogs are operated on the federal, state, county, and local levels and are used for a wide variety of duties, similar to those of other nations. Their duties generally include detecting illegal narcotics, explosives, and other weapons, search-and-rescue, and cadaver searches. The most common breeds for everyday duties are the German Shepherd and the Belgian Malinois, though other breeds may be used to perform specific tasks.On the federal level, police dogs may be seen in some airports assisting Transportation Security Administration officials search for explosives and weapons, or by Customs and Border Protection searching for concealed narcotics and people. Some dogs may also be used by tactical components of such agencies as the Bureau of Alcohol, Tobacco, Firearms, and Explosives, the Federal Bureau of Investigation, and the United States Marshals Service. Federally owned police dogs play a vital role in homeland security. An expert on police dogs, L. Paul Waggoner of the Canine Performance Sciences Program at Auburn University said, "detector dogs are a critical component of national security – and they also provide a very visible and proven deterrent to terrorist activities." The American Kennel Club estimates that between 80–90 percent of dogs purchased by the U.S. Department of Homeland Security and U.S. Department of Defense come from foreign vendors, mostly located in Europe.Most police agencies in the United States – whether state, county, or local – use police dogs as means of law enforcement. Often, even the smallest of departments operates a K-9 division of at least one dog; in these cases, police dogs will usually serve all purposes deemed necessary, most commonly suspect apprehension and narcotics detection, and teams are often on call. In larger cities and metropolitan areas, police departments regularly employ dozens of police dogs. In these cases, individual dogs often serve individual purposes in which each particular animal is specialized, and teams usually serve scheduled shifts. In both cases, police dogs are almost always cared for by their specific handlers. The U.S. Fish and Wildlife Services agency requires police dogs to undergo annual in-service training to recertify their skills and credentials. This training must last at least 24 hours each year.

Under the Federal Law Enforcement Animal Protection Act, it is a felony to assault or kill a law enforcement animal, including police dogs and police horses, in all 50 states. However, police dogs are not treated as police officers for the purpose of the law, and attacking or killing a police dog is not punishable in the same manner as attacking or killing a human police officer. Although many police departments formally swear dogs in as police officers, this swearing-in is purely honorary, and carries no legal significance.Police dogs also play a major role in American penal systems. Many jails and prisons will use special dog teams as a means of intervening in large-scale fights or riots by inmates. Also, many penal systems will employ dogs – usually bloodhounds – in searching for escaped prisoners.
In October 2017, the U.S. House Oversight and Government Reform Intergovernmental Affairs Subcommittee held a hearing about whether there is a sufficient supply of dogs that can be trained as police dogs. Congressman Mike Rogers (R-AL) said that the continued ISIS-inspired attacks in the U.S. and all over the world "have driven demand through the roof" for police dogs.
The Marshall Project maintains a database of police dog bites across the United States.

Supreme Court cases
The United States Supreme Court is the highest federal court in the United States of America. Some U.S. Supreme Court cases that pertain to police dogs are:

United States v. Place (1983) – The Court held that the sniff of a specially trained police dog is sui generis and it does not violate the Fourth Amendment's prohibition of unreasonable search and seizure for one to sniff a person's personal items in a public place, even if done without a warrant.
City of Indianapolis v. Edmond (2000) – The Court held that is unconstitutional to set up a highway checkpoint for the primary purpose of illegal narcotic discovery. In the case, the Indianapolis Police Department was using police dogs to detect narcotics at the checkpoint without reasonable suspicion.
Illinois v. Caballes (2005) – The Court held that police do not need probable cause to bring a drug-detection dog to a vehicle during a legal traffic stop, and searches by a police dog do not count as an invasion of privacy, because a well-trained one will only alert to the presence of illegal substances.
Florida v. Harris (2013) – The Court held that a police dog's alert to the exterior of a vehicle gives the officer probable cause to search the vehicle without a warrant. Further, the Court affirmed that the state does not have to prove each dog's reliability in order for evidence gathered from them to be valid in court.
Florida v. Jardines (2013) – The Court held that evidence collected from a police dog at the front door of a house cannot be used in court. The front porch of a house is considered a private place, and the police need probable cause and a search warrant to bring a police dog to the front door.
Rodriguez v. United States (2015) – The Court held that, without reasonable suspicion, the use of a police dog after the conclusion of a legal traffic stop violates the Fourth Amendment.

See also
Detection dog
Dogs in warfare
Nosework
Working dog
Passage 2:
Dog
The dog (Canis familiaris or Canis lupus familiaris) is a domesticated descendant of the wolf. Also called the domestic dog, it is derived from extinct Pleistocene wolves, and the modern wolf is the dog's nearest living relative. Dogs were the first species to be domesticated by hunter-gatherers 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-rich diet that would be inadequate for other canids.The dog has been selectively bred over millennia for various behaviors, sensory capabilities, and physical attributes. Dog breeds vary widely in shape, size, and color. They perform many roles for humans, such as hunting, herding, pulling loads, protection, assisting police and the military, companionship, therapy, and aiding disabled people. Over the millennia, dogs became uniquely adapted to human behavior, and the human–canine bond has been a topic of frequent study. This influence on human society has given them the sobriquet of "man's best friend".

Taxonomy
In 1758, the Swedish botanist and zoologist Carl Linnaeus published in his Systema Naturae, the two-word naming of species (binomial nomenclature). Canis is the Latin word meaning "dog", and under this genus, he listed the domestic dog, the wolf, and the 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.In 1999, a study of mitochondrial DNA (mtDNA) indicated that the domestic dog may have originated from the grey wolf, with the dingo and New Guinea singing dog 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 published in 2005, the mammalogist 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 Linnaeus in 1758 and, dingo named by Meyer in 1793. Wozencraft included hallstromi (the New Guinea singing dog) as another name (junior synonym) 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/Species Survival Commission's Canid Specialist Group considered the dingo and the New Guinea singing dog to be feral Canis familiaris and therefore did not assess them for the IUCN Red List of Threatened Species.

Evolution
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 powder and buried under large, thick basalt blocks. The dog had died of canine distemper. Earlier remains dating back to 30,000 years ago have been described as Paleolithic dogs, but their status as dogs or wolves remains debated because considerable morphological diversity existed among wolves during the Late Pleistocene.This timing indicates that the dog was the first species to be domesticated in the time of hunter–gatherers, which predates agriculture. DNA sequences show that all ancient and modern dogs share a common ancestry and descended from an ancient, extinct wolf population which was distinct from the modern wolf lineage. Most dogs form a sister group to the remains of a Late Pleistocene wolf found in the Kesslerloch cave near Thayngen in the canton of Schaffhausen, Switzerland, which dates to 14,500 years ago. The most recent common ancestor 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 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 of the current evidence infers that the dog was domesticated in 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. In the Victorian era, directed human selection developed the modern dog breeds, 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 change and were formed into today's modern breeds due to artificial selection 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, present day 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.

Biology
Anatomy
Skeleton
All healthy dogs, regardless of their size and type, have an identical 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 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 mastiffs and miniaturised for smaller types such as terriers; dwarfism has been selectively utilised for some types where short legs are advantageous such as dachshunds and corgis. 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 sighthounds, 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. One study suggested that dogs can feel Earth's magnetic field.

Coat
The coats 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 and a soft down hair, 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 behaviors, anxiety behaviors, fear of noise, and fear of unfamiliar people or animals.

Tail
There are many different shapes for dog tails: 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 and hip dysplasia, blindness, deafness, pulmonic stenosis, cleft palate, and trick knees. Two severe medical conditions significantly affecting dogs are pyometra, affecting unspayed females of all breeds and ages, and Gastric dilatation volvulus (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 fleas, ticks, mites, hookworms, tapeworms, roundworms, and heartworms, which is a roundworm species that lives in the hearts of dogs.
Several human foods and household ingestible are toxic to dogs, including chocolate solids, causing theobromine poisoning, onions and garlic, causing thiosulphate, sulfoxide or disulfide poisoning, grapes and raisins, macadamia nuts, and 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. 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, dental and heart disease, epilepsy, cancer, hypothyroidism, and arthritis.

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 dogs, 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 dogs live on average 1.2 years longer than purebred dogs.

Reproduction
In domestic dogs, 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. They will experience subsequent estrous cycles semiannually, during which the body prepares for pregnancy. At the peak of the cycle, females will become estrous, mentally and physically receptive to copulation. Because the 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, with an average of 63 days, although the length of gestation can vary. An average litter consists of about six puppies.

Neutering
Neutering is the sterilization of animals, usually by removing the male's testicles or the female's ovaries and uterus, to eliminate the ability to procreate and reduce 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 (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, 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, 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 in female dogs and prostate cancer in males and osteosarcoma, hemangiosarcoma, cruciate ligament rupture, obesity, and diabetes mellitus 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 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, Basset Hound, Cairn Terrier, Brittany, German Shepherd Dog, Leonberger, and West Highland White Terrier), it was found that inbreeding decreases litter size and survival. Another analysis of data on 42,855 Dachshund litters found that as the inbreeding coefficient increased, litter size decreased and the percentage of stillborn puppies increased, thus indicating inbreeding depression. In a study of 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 apes, 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 catecholamine synthesis 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 in humans, which cause hypersociability at the expense of problem-solving ability.

Intelligence
Researchers have tested dogs' ability to perceive information, retain it as knowledge, and apply it to solve problems. Studies of two dogs suggest that dogs can learn by inference and have advanced memory skills.  A study with Rico, a 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, 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 horses, chimpanzees, or cats. One limited study of 18 household dogs found that they lacked spatial memory, and were more focused on the "what" of a task rather than the "where".Dogs demonstrate a theory of mind by engaging in deception. An experimental study showed compelling evidence that Australian dingos 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 humans. Another study revealed that after undergoing training to solve a simple manipulation task, dogs faced with an unsolvable 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.: xii  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 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 typically 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 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.Coyotes and big cats have also been known to attack dogs. In particular, leopards are known to have a preference for dogs and have been recorded to kill and consume them, no matter what their size. Siberian tigers in the 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 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. 
Of the twenty-one amino acids common to all life forms (including selenocysteine), dogs cannot synthesize ten: arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. 
Also more like cats, dogs require arginine to maintain 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 dingos on that continent
The Andamanese peoples, who were isolated when 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 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, herding, pulling loads, protection, assisting police and the military, companionship and aiding disabled individuals. This influence on human society has given them the nickname "man's best friend" in the Western world. In some cultures, however, dogs are also a source of meat.

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", 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 model of dog-human relationships. However, it has been disputed that "trying to achieve status" is characteristic of dog-human interactions. The idea of the "alpha dog" trying to be dominant is based on a disproved theory about wolf packs. 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 dog dancing and 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 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 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),  hunting (hounds, pointers) and rodent control (terriers). Other types of working dogs include search and rescue dogs, detection dogs trained to detect 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 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 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.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 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 U.S., cats 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) 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 hookworms 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 association between dog ownership and adult physical activity levels has been reviewed by several authors.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 guidance, protection, loyalty, fidelity, faithfulness, alertness, and love. In ancient Mesopotamia, from the Old Babylonian period until the Neo-Babylonian, dogs were the symbol of Ninisina, the goddess of healing and medicine, and her worshippers frequently dedicated small models of seated dogs to her. In the 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. Dogs are also associated with the Greek goddess Hecate. In Norse mythology, a dog called Garmr guards Hel, a realm of the dead. 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. A black dog is also considered to be the vahana (vehicle) of Bhairava (an incarnation of Shiva).In Christianity, dogs represent faithfulness. Within the Roman Catholic denomination specifically, the iconography of Saint Dominic includes a dog, after the saint'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 – 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
Passage 3:
Flesh and Bone (film)
Flesh and Bone is a 1993 American neo noir mystery thriller film written and directed by Steve Kloves that stars Meg Ryan, Dennis Quaid and James Caan. Gwyneth Paltrow is featured in an early role, for which she received some praise.

Plot
A family in rural Texas finds a boy, Arlis, who says he is lost. They take him into their home, feed him, and give a place to sleep. But the boy later lets his father, Roy (James Caan), into the house to commit a robbery. When they are discovered, Roy brutally murders the family, which the boy witnesses. The sole survivor is a baby girl.
Time passes, and Arlis (Dennis Quaid) lives a solitary life in which he drives a truckload of goods and novelties to restock vending machines and arcade games in roadside stores and restaurants. Making a stop at a roadhouse where a rowdy party is being held, he spots Kay (Meg Ryan), a woman who pops up out of a cake at the party and then passes out because she's been drinking liquor.
Arlis ends up giving her a ride home, a long drive, while continuing to make his rounds. Upon coming home, Kay sees that her husband Reese has sold the furniture, having lost their money gambling. She packs up her remaining belongings and leaves with Arlis. They spend more time together and grow close.
Meanwhile, a young woman named Ginnie (Gwyneth Paltrow) now travels with a much older Roy. She is a grifter who will pretend to be a mourner in order to steal the jewelry from a dead body at a funeral home. Ginnie brings an injured Roy to his estranged son, Arlis, to tend to his injury.
Passing the house where he grew up, Arlis realizes that Kay was the infant who survived the long-ago murders. Roy figures this out as well. He begins talking about tying up loose ends. It leads to a confrontation, and Arlis shoots Roy dead. Ginnie goes off on her own, and Kay and Arlis go their separate ways.

Cast
Dennis Quaid as Arlis Sweeney
Meg Ryan as Kay Davies
James Caan as Roy Sweeney
Gwyneth Paltrow as Ginnie
Scott Wilson as Elliott
Gail Cronauer as Emma
John Hawkes as Groom

Location
Principal photography began on October 5, 1992 and completed on December 26, 1992.
It was filmed in Lockhart and Marfa, Texas, as well as at the Mustang Mott store owned by Maxine McCoy, in Westhoff, Texas.Producer Mark Rosenberg died of a heart attack suffered on the film's location in Stanton, Texas.
As the end credits begin, the film is dedicated to him.

Reception
On Rotten Tomatoes, Flesh and Bone holds a 65% approval rating from 26 reviews, with an average rating of 6/10. On Metacritic, the film has a score of 57 out of 100 based on 21 reviews, indicating "mixed or average reviews". Audiences polled by CinemaScore gave the film an average grade of "C" on an A+ to F scale.
Passage 4:
A Dog's Purpose (film)
A Dog's Purpose is a 2017 American family comedy-drama adventure film directed by Lasse Hallström and written by W. Bruce Cameron, Cathryn Michon, Audrey Wells, Maya Forbes, and Wally Wolodarsky, based on the 2010 novel of the same name by W. Bruce Cameron. The film stars Britt Robertson, KJ Apa, Juliet Rylance, John Ortiz, Kirby Howell-Baptiste, Peggy Lipton, Dennis Quaid, and Josh Gad. The first film from the novel covers themes of loyalty, grief, dysfunctional family, and reincarnation from one lifetime to another.
The film is a co-production between Amblin Entertainment, Reliance Entertainment, Walden Media, and Pariah Entertainment Group. It was released by Universal Pictures on January 27, 2017, and grossed $205 million worldwide. It was Peggy Lipton's final film role before her death in 2019.
A sequel, titled A Dog's Journey, was released on May 17, 2019.

Plot
In the 1950s, a feral puppy wonders about life's true purpose. Weeks later, he is caught by dogcatchers, whisked away to the pound, and euthanized.
The dog is reborn as a Red Retriever in 1961. Leaving his cage at a puppy mill, he is taken by two garbage men, who plan to sell him. Left locked inside their pick-up truck, he begins to die of heatstroke, but is rescued by a kindhearted mother and her eight-year-old son, Ethan Montgomery. They break the truck's window and bring him home, naming him Bailey. Bailey and Ethan bond quickly, especially over the summer at Ethan's grandparents' farm, and Bailey decides Ethan alone is his purpose. Ethan gives him the nickname “Boss Dog”. Years pass, and after several attempts at advancing in his job fail, Ethan's father has become an alcoholic. In 1969, Ethan meets a girl named Hannah at a fair with Bailey, and they soon begin dating. They spend their summer together, happily, through senior year. They plan to go to the same college, Ethan getting a football scholarship and Hannah with an academic one. At home one night, Ethan's drunken father becomes abusive towards his mother and him. Ethan kicks him out. Later in 1971 at a football game watched by scouts, Ethan is offered a full scholarship to Michigan State University. That night, his vindictive classmate Todd throws a lit firecracker into Ethan's house, causing a house fire. Bailey alerts Ethan, who saves his mother out through an upstairs window. Ethan lowers her, then Bailey. However, he loses his rope and must jump, fracturing his leg and ending his athletic scholarship. Bailey attacks Todd, who is arrested by the police when firecrackers fall out of his pocket. Now, Ethan must go to an agricultural school, where he will learn to take over the farm. Depressed, Ethan breaks up with Hannah before leaving for college, while Bailey stays with Ethan's grandparents. Bailey ages and Ethan comes to say goodbye.
Bailey is reborn as a female German Shepherd puppy, growing into a police dog named Ellie, in the late 1970s/early 1980s, while fully retaining memories of her past lives. Ellie is partnered with lonely officer Carlos Ruiz who has recently split up with his partner, of the Chicago Police Department, and works hard at "seeking" and "finding", now seeing the job as life's purpose. They form a close bond, ending after Ellie saves a girl, kidnapped by her mother's ex-boyfriend, from drowning and is then fatally shot by the kidnapper while protecting Carlos.
Reborn in the mid-1980s as a male Corgi, Bailey is adopted by Atlanta college student Maya, who names him Tino. Lonely, he tries to find her happiness. She meets Al, a classmate, after Tino falls for Al's dog, a female Landseer named Roxy. They marry, having three children. Tino is heartbroken when one day Roxy does not return from the vet. As Tino ages and dies, he thanks Maya for giving him one of his best lives.
Bailey reincarnates again, this time as a St. Bernard/Australian Shepherd mix puppy in 2014. At first adopted by a woman named Wendi, he is named Waffles. Unfortunately, Wendi's husband neglects him, refuses to let her keep him inside, and after several years, abandons him. Waffles searches for a new life, gradually making his way back to where he spent summers as Bailey. He joyfully reunites with his old master Ethan, now in his 60s, lonely on his grandparents' old farm, now his. Not recognizing him, Ethan takes him to the local animal shelter, but later reclaims him, naming him Buddy. Sensing that he has finally found his true purpose, he reunites Ethan with a widowed Hannah, and they get married. Buddy shows Ethan that he is his “Boss Dog”, by performing tricks and responding to phrases that were known only to the two of them many years back. Ethan finds Bailey's collar, now old and rusty, and places it back on Bailey's neck, and they resume playing exactly the way they did so long ago. Bailey narrates that life is about having fun, saving others, finding someone to be with, not getting upset over the past or the future, and living for today.

Cast
Josh Gad as the voice of Bailey, Ellie, Tino and Buddy, the reincarnations of "Boss Dog", the main protagonist.
Dennis Quaid as Ethan Montgomery, an old man who runs a farm.
KJ Apa as teenaged Ethan Montgomery, a popular football player who later gets injured and must become a farmer.
Bryce Gheisar as eight-year-old Ethan Montgomery, a young boy interested in comics and football.
Juliet Rylance as Elizabeth Montgomery, Ethan's mother in an unhappy and abusive marriage to Jim, whom she later divorces.
Peggy Lipton as Hannah, an old woman who is widowed and has two children.
Britt Robertson as teenaged Hannah, the supportive and intelligent girlfriend of Ethan.
John Ortiz as Carlos Ruiz, Ellie’s partner who trains her as a police dog.
Kirby Howell-Baptiste as Maya, a shy young woman who adopts Tino.
Pooch Hall as Al, a young man who dates and later marries Maya, and has three children with her.
Luke Kirby as Jim Montgomery, Ethan's father in an unhappy and abusive marriage with Elizabeth and an alcoholic.
Michael Bofshever as Bill, Ethan's grandfather and a farmer.
Gabrielle Rose as Fran, Ethan's grandmother.
Logan Miller as Todd, a former friend of Ethan’s who is vindictive and jealous of him.

Production
In 2015, DreamWorks acquired the film rights for Cameron's novel. On May 8, 2015, it was announced Lasse Hallström would direct the film. On August 5, 2015, Britt Robertson and Dennis Quaid joined the cast. On September 18, 2015, Pooch Hall was cast in the film. On October 15, 2015, Bradley Cooper joined the cast to play Bailey's inner voice, but the role was eventually performed by Josh Gad. Principal photography began on August 17, 2015. During production, controversy ensued over treatment of a dog during filming.

Release
In December 2015, the film switched from a DreamWorks Pictures release to under the Amblin Entertainment banner as per Amblin Partners' newly enacted branded strategy. The film was released by Universal Pictures on January 27, 2017. Universal also distributed it overseas, except for countries where Mister Smith Entertainment handled international sales.

Reception
Box office
A Dog's Purpose has grossed $64.5 million in the United States and Canada and $140.5 million in other territories for a worldwide gross of $205 million, against a production budget of $22 million.In North America, it was released alongside Resident Evil: The Final Chapter and Gold, and was projected to gross $18–22 million from 3,050 theaters in its opening weekend, slightly lower than initial $27 million tracking had the film debuting to before boycotts against the film were called for. It made $466,000 from Thursday-night previews and $5.3 million on its first day. It ended up debuting to $18.2 million, finishing second at the box office behind the second weekend of Universal's own Split. The film dropped 40.6% in its second weekend, grossing $10.8 million and finishing third at the box office.

Critical response
On Rotten Tomatoes, the film has an approval rating of 35% based on reviews from 142 critics, with an average rating of 4.8/10. The site's critics consensus reads, "A Dog's Purpose offers an awkward blend of sugary sentiment and canine suffering that tugs at animal-loving audiences' heartstrings with shameless abandon." On Metacritic, the film has a weighted average score of 43 out of 100 based on 32 critics, indicating "mixed or average reviews". Audiences polled by CinemaScore gave the film an average grade of "A" on an A+ to F scale.Andrew Barker of Variety wrote: "Viewed in a vacuum, it’s hard to fault the movie’s earnestness; Hallström’s canine cinema pedigree (which includes the superior Hachi: A Dog's Tale) shows through; and Rachel Portman's score is understandably sentimental without going completely saccharine." 
Frank Scheck of The Hollywood Reporter wrote: "While the human performers are more than adequate, there’s no doubt that the canine stars carry the day. Their utter irresistibility helps a long way in terms of getting past the corny plot machinations of A Dog’s Purpose."

Home media
A Dog's Purpose was released on digital HD on April 18, 2017, and was followed by a release on Blu-ray and DVD on May 2, 2017, from Universal Pictures Home Entertainment. The film topped the home-video sales chart for the week ending on May 7, 2017.

Controversy
On January 18, 2017, a video surfaced on TMZ showing footage taken from the set of the film, which shows a male German Shepherd named Hercules being dragged and dipped into rushing water while visibly resisting. After a cut in the video, the next clip shows the dog being submerged in the water at the other end of the tank while a voice on set can be heard shouting "CUT IT!", and various people are then seen rushing towards the dog. The American Humane Association, which ensures that animals are not harmed in entertainment productions, announced that its representative on set had been suspended over the incident, and that the incident was under further investigation. PETA called for a boycott of the film. Actor Josh Gad, who voices the dog in the movie and was not on set during the making of the film, said he was "shaken and sad to see any animal put in a situation against its will." Director Lasse Hallström said via Twitter that he "did not witness" the actions in the video, and was "very disturbed" by the footage. Due to the release of the video, Universal Pictures cancelled the film's scheduled January 19 Los Angeles premiere.Amblin Entertainment released a statement in regards to the incident, saying, "on the day of the shoot, Hercules did not want to perform the stunt portrayed on the tape, so the Amblin production team did not proceed with filming that shot," and  "Hercules is happy and healthy." On February 4, 2017, the American Humane Association reported that an independent third-party animal-cruelty expert had concluded that safety measures on the set of the film were in place and the video had been deliberately edited to mislead the public.

Sequel
On June 21, 2017, CEO of Amblin Entertainment Michael Wright announced that a sequel was in development. On August 26, 2018, Universal began production on the sequel, which is directed by Gail Mancuso, and was released on May 17, 2019. In addition to Quaid and Gad reprising their roles, the cast also includes Marg Helgenberger (replacing Peggy Lipton, who had become seriously ill), Betty Gilpin, Kathryn Prescott, and Henry Lau. The trailer for the sequel, titled A Dog's Journey, was released in January 2019.

Answer the question based on the given passages. Only give me the answer and do not output any other words.

Question: Who is the spouse of the actor of Ethan in A Dog's Purpose?



Answer: Meg Ryan