Guinea pig

• 1. Introduction

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  The guinea pig, known to science as Cavia porcellus, is a rodent that gets almost everything about its name wrong. It is not native to Guinea, and it is not closely related to pigs. Breeders prefer the word cavy, pronounced KAY-vee, while laboratories and the general public say guinea pig. Today the animal lives in family homes, research laboratories and kitchens on several continents. How did a grassland animal from South America end up in so many places? Where did such a misleading name come from? And why does a single small creature mean a beloved pet in one country and a festival meal in another?

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• 2. Andean Origins

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  As early as 5000 BC, tribes in the Andean region began raising a small grassland animal for food. Their territory covered the present-day southern part of Colombia, Ecuador, Peru and Bolivia. This came some thousands of years after the domestication of the South American camelids. In the region, the animal is called cuy, a Spanish word taken from the Quechua quwi.

  The domestic guinea pig does not exist naturally in the wild. Studies from 2007 to 2010 used molecular markers and measurements of the skulls and skeletons of living and mummified animals. They pointed to Cavia tschudii as the most likely ancestor. Other wild cavies, including C. aperea and C. fulgida, are close relatives that are still common across South America.

  The Moche people of ancient Peru worshipped animals and often showed the guinea pig in their art. Spanish settlers wrote that the Inca of Peru preferred guinea pigs as their sacrificial animal. Archaeological digs and transcribed Quechua mythology support those accounts. They suggest the rituals served several purposes: appeasing the gods, accompanying the dead and reading the future.

  From about 1200 until the Spanish conquest in 1532, indigenous breeders used selective breeding to produce many varieties. These varieties form the basis of some modern domestic breeds. Many households in the Andean highlands still raise the animal today.

  Two cavies named in the 20th century, C. anolaimae and C. guianae, may not be wild at all. They may be domestic guinea pigs that returned to the wild after being released.

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• 3. Across the Ocean

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  In the early 1500s, Spanish, Dutch and English traders carried guinea pigs to Europe. There they quickly became exotic pets among the upper classes and royalty, including Queen Elizabeth I.

  The earliest known written account dates from 1547 and describes an animal in Santo Domingo. Cavies are not native to Hispaniola, so the animal was believed to have been brought there earlier by Spanish travelers. Zooarchaeological evidence points to an older arrival. South American migrants who made ceramics likely introduced guinea pigs to the West Indies around 500 BC. On Puerto Rico, the animal was present in the Ostionoid period, long before any Spaniard arrived.

  In 1554, the Swiss naturalist Conrad Gessner gave the first description of the guinea pig in the West. The earliest known European illustration is a painting by an unknown artist, dated to 1580, in the National Portrait Gallery in London. It shows a girl in Elizabethan dress holding a tortoise-shell guinea pig in her hands. Her two brothers stand on either side, and one of them holds a pet bird.

  The oldest recorded guinea pig remains in England come from the same period. Excavators at Hill Hall, an Elizabethan manor house in Essex, found a partial cavy skeleton dated to around 1575.

  The animal's two-part scientific name arrived much later. Erxleben first used it in 1777, joining the generic designation made by Pallas in 1766 to the specific one conferred by Linnaeus in 1758.

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• 4. Names and Misnomers

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  The second half of Cavia porcellus is Latin for "little pig." The first half, Cavia, is Neo-Latin. It comes from cabiai, the animal's name in the language of the Galibi tribes once native to French Guiana. Cabiai may be an adaptation of the Portuguese word çavia, now spelled savia, which itself derives from the Tupi word saujá, meaning rat.

  The origin of "guinea" in the English name is unclear. One explanation holds that the animals reached Europe by way of Guinea, so people assumed they came from there. English also used "Guinea" for any far-off, unknown country, so the name may simply signal exotic origins. Another idea is that it is a corruption of "Guiana," an area of South America.

  A popular story says the animals were sold for the price of a guinea coin. The timeline defeats it. The guinea coin was first struck in England in 1663, yet William Harvey used the term "Ginny-pig" as early as 1653. Others suggest "guinea" may be an alteration of coney, an old word for rabbit. Edward Topsell's 1607 treatise on quadrupeds called guinea pigs "pig coneys."

  How they came to be called pigs is also unclear. They have large heads for their bodies, stout necks and rounded rumps with no real tail. Some of their sounds resemble those of pigs, and they spend a great deal of time eating. They can survive for long periods in small quarters, like a pig pen, and were easy to transport by ship.

  Other languages lean on pigs too. The German word, Meerschweinchen, means "little sea pig," apparently because the animals arrived from overseas. Polish says swinka morska, Hungarian says tengerimalac, and Russian says morskaya svinka. The French use cochon d'Inde, meaning Indian pig, or cobaye. The Dutch called it Guinees biggetje, or Guinean piglet. In Portuguese it is cobaia, from the Tupi word, or porquinho da India, meaning little Indian pig.

  The pig link is not universal. Spanish speakers say conejillo de Indias, "little rabbit of the Indies." In Chinese the animal is tunshu, "pig mouse," and sometimes helanzhu, "Netherlands pig," or tianzhushu, "Indian mouse."

  The Japanese word morumotto borrows from the name of another mountain-dwelling rodent, the marmot. Dutch traders used that word when they first brought guinea pigs to Nagasaki in 1843.

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• 5. Life in the Herd

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  Pet guinea pigs usually weigh between 700 and 1200 grams and measure 20 to 25 centimetres in length. That is large for a rodent. Most live four to five years, though some reach eight. According to Guinness World Records, the longest-lived guinea pig reached 14 years, 10 months and 2 weeks. Their four front teeth never stop growing, so they gnaw on wood and similar materials to wear them down.

  In the 1990s, a minority of scientists argued that guinea pigs, chinchillas and degus are not rodents at all. They proposed a separate order of mammals. Later research with wider sampling restored the consensus that guinea pigs are rodents.

  Wild cavies roam grassy plains, where they fill an ecological niche similar to that of cattle. They live in small herds made up of several females called sows, one male called a boar, and their young. The young are called pups, not piglets, which breaks from the pig vocabulary. The herd moves together while grazing but stores no food. Cavies do not dig burrows or build nests. Instead they shelter in the burrows of other animals and in crevices and tunnels formed by vegetation. They are most active at dawn and dusk, when predators have trouble spotting them.

  A guinea pig can learn a complicated path to food and still follow it accurately months later. It can jump small obstacles but cannot jump high, and most are poor climbers. Startled animals either freeze for long periods or dash for cover. Larger groups stampede in haphazard directions, which helps confuse predators. When a guinea pig is happily excited, it may leap into the air in little hops. The behavior is called popcorning, and it is comparable to the happy hops of rabbits, known as binkies. They swim well but dislike being wet.

  Their eyesight is weaker than a human's for distance and color, but they see about 340 degrees around them. They see in partial color. Guinea pigs groom themselves and each other, rubbing a milky-white secretion from their eyes into the hair. Groups of boars often chew one another's hair. This is a way of setting rank rather than a friendly gesture. Rank is also settled by biting, especially of the ears, as well as raised fur, aggressive noises, head thrusts and leaping attacks.

  Vocalization is the main way guinea pigs communicate. The loudest call is the wheek, a name that imitates the sound. It expresses general excitement at the sight of the owner or at feeding time. A lost guinea pig may wheek for help. A bubbling or purring sound means the animal is enjoying itself, perhaps while being petted. A rumble usually signals dominance, though it can also come from fear or anger. A courting male purrs deeply while swaying and circling the female, a display called rumblestrutting. Rapid teeth chattering is a warning. Squealing or shrieking means pain or danger. Chirping is rare, is likened to bird song, and is tied to stress, discomfort or a baby that wants to be fed.

  Guinea pigs breed fast. Females can be fertile at four weeks old, and males reach maturity in three to five weeks. A sow can have as many as five litters in a year, and she can become pregnant again 6 to 48 hours after giving birth. Gestation lasts 59 to 72 days, averaging 63 to 68. Litters range from one to six pups, with three the average. The largest recorded litter was nine. Most rodent young are helpless at birth, but guinea pig pups are born with hair, teeth, claws and partial eyesight. They can move at once and eat solid food, although they keep suckling.

  The mother has only two nipples, yet she can readily raise litters of two to four pups. Lactating females in a group help with mothering, and a sow may adopt the pups of another. Pregnancy brings serious risks. Toxemia of pregnancy, a form of hypertension, kills many pregnant females and appears most common in hot climates. A female that never gives birth faces a different danger. After six months of age, a joint in her pelvis may fuse, and a later pregnancy can end in death during labor.

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• 6. Care and Companionship

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  In Switzerland, keeping a single guinea pig is illegal, because a lone animal is considered to suffer. There is even a service for renting guinea pigs, to replace a dead cage-mate for a time. Sweden has similar laws. Guinea pigs recognize and bond with individual companions. Tests show that a boar's stress response to a strange environment drops when a bonded female is present, but not when unfamiliar females are. Groups of sows are common, as are sows with a neutered boar. Boars can live together if they meet early, have enough space and no females are present.

  Other species make poor companions. Larger animals may treat guinea pigs as prey. Rabbits synthesize their own vitamin C, so they have different nutritional needs, and they can carry respiratory infections from Bordetella and Pasteurella. Gerbils and hamsters may raise the rate of infections and can act aggressively.

  Empirical studies show that larger cages and enrichment such as hiding places improve guinea pig welfare, although owners often provide less space than recommended. Wire mesh floors can cause injury and an infection called bumblefoot, so solid-bottomed cages are typical. One popular design uses wire grid panels and plastic sheeting and is known as C&C, for cubes and coroplast. Red cedar and pine bedding were once common, but both contain phenols and oils believed to be harmful. Aspen, paper and corn cobs are alternatives. Guinea pigs are messy. They jump into their food bowls, and their urine sometimes crystallizes on cage surfaces. After a cleaning, a guinea pig typically urinates and drags its lower body across the floor to mark its territory.

  Ten milligrams of vitamin C a day, or twenty if pregnant, keeps a guinea pig from fatal scurvy. Like humans, and unlike most other mammals, guinea pigs cannot make this vitamin themselves. They can get it from broccoli, apple, cabbage, carrot, celery and spinach, from supplements, or from properly handled fresh pellets.

  Their natural diet is grass, and their molars grow continuously to grind it. To draw nutrients from tough fiber, they ferment it in the cecum and expel the result as cecotropes. They then eat these directly from the anus, a habit called cecotrophy that they share with rabbits and hares. Fresh grass hay such as timothy is the foundation of a good diet. Alfalfa divides opinion. Some owners and veterinary organizations warn that it can cause obesity and, through excess calcium, bladder stones. Published scientific sources note that it supplies protein, amino acids and fiber.

  Guinea pigs are fickle eaters. They learn early what counts as food and may starve rather than accept a new type. They gnaw on cloth, paper, plastic and rubber, so owners often guinea pig proof the house. Several plants are poisonous to them, including bracken, foxglove, hemlock, lily of the valley and rhubarb. So are plants that grow from bulbs, such as tulip and onion, along with ivy and oak leaves.

  Their normal body temperature is 101 to 104 F, and the ideal room temperature is about 65 to 75 F, similar to a human's. Temperatures consistently above 90 F have been linked to hyperthermia and death, especially among pregnant sows. As prey animals, guinea pigs hide pain, so a problem may not show until it is advanced. They are extremely sensitive to most antibiotics, including penicillin, which destroys intestinal flora and can quickly bring on diarrhea and death.

  Mange mites called Trixacarus caviae are a common cause of hair loss. Running lice, Gliricola porcelli, can be seen moving through the fur. Some inherited problems are known. The roan coloration of Abyssinian guinea pigs is linked with eye disorders and digestive problems. Waltzing disease combines deafness with a tendency to run in circles.

  A guinea pig that knows its owner will whistle on the owner's approach. It learns to whistle at the rustle of a plastic bag or the opening of the refrigerator door. The English shorthair, also called the American, is the most common variety in pet stores. The Abyssinian has a ruffled coat with rosettes. The Peruvian and the Sheltie, or Silkie, are straight longhaired breeds, and the Texel is a curly longhair. Shorthairs are brushed weekly, while longhairs may need grooming daily.

  Cavy clubs run shows worldwide. The American Cavy Breeders Association, an adjunct to the American Rabbit Breeders' Association, governs the United States and Canada. The British Cavy Council oversees the United Kingdom, and similar bodies exist in Australia and New Zealand. Each publishes a standard of perfection that decides which breeds may be shown. People can be allergic to guinea pigs. Two major allergens, Cav p I and Cav p II, have been found in the animal's urine, saliva and dander. Allergy shots can work, but treatment can take up to 18 months.

  The animal has also found its way into stories. Ellis Parker Butler wrote the short story "Pigs Is Pigs," in which two guinea pigs held at a railway station breed unchecked while humans argue over freight charges. That tale inspired the Star Trek episode "The Trouble with Tribbles," written by David Gerrold. Beatrix Potter wrote The Fairy Caravan and Michael Bond wrote the Olga da Polga series, both with guinea pig heroes. In C. S. Lewis's The Magician's Nephew, a guinea pig is the first creature to travel to the Wood between the Worlds.

  On screen, a guinea pig named Rodney, voiced by Chris Rock, appeared in the 1998 film Dr. Dolittle. Linny the Guinea Pig co-stars in Wonder Pets, and a South Park episode called "Pandemic 2: The Startling" features giant guinea pigs in costumes. The 2009 film G-Force starred guinea pigs trained as government operatives. Advertisers used them in the 1990s and 2000s for Egg Banking plc, Snapple and Blockbuster Video.

  In the Andes, though, the animal has a very different job.

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• 7. Feast and Ritual

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  Peruvians eat an estimated 65 million guinea pigs each year. A famous painting of the Last Supper in the main cathedral in Cusco shows Christ and his disciples dining on one. The animal is also given as a gift, appears in spoken metaphors and takes part in religious events in both rural and urban Peru.

  In the Antonio Raimondi province of eastern Peru, the festival of jaca tsariy, meaning "collecting the cuys," is celebrated in many villages and in smaller ceremonies in Lima. It blends Catholicism with pre-Columbian practice and centers on local patron saints. In some towns a servant called a sirvinti goes from door to door collecting donated guinea pigs. In others the animals are released in a mock bullfight. Meals such as cuy chactado are always served. Some communities frame the killing and serving of the animal as a symbolic satire of local politicians or important figures.

  In the Tungurahua and Cotopaxi provinces of central Ecuador, guinea pigs feature in celebrations of Corpus Christi. The Ensayo is a community meal. At the Octava, greased poles called castillos are raised with prizes tied to the crossbars, and several guinea pigs may be hung from them. The Peruvian town of Churin holds an annual festival where guinea pigs in elaborate costumes compete. Huancayo, Cusco, Lima and Huacho also hold festivals with costumes and guinea pig dishes. Most celebrations fall on National Guinea Pig Day, the Dia Nacional del Cuy, on the second Friday of October.

  Folk doctors called curanderos use guinea pigs to diagnose jaundice, rheumatism, arthritis and typhus. They rub the animal against the body of the sick person, treating it as a supernatural medium. Black guinea pigs are considered especially useful. The animal may be cut open and its entrails examined to judge whether a cure worked. These methods are widely accepted in parts of the Andes where Western medicine is unavailable or distrusted.

  Traditionally the meat was reserved for ceremonial meals and treated as a delicacy by indigenous people of the highlands. Since the 1960s it has become acceptable for everyone to eat it. It remains a significant part of the diet in Peru and Bolivia, in the Ecuadorian Sierra, and in the Colombian departments of Cauca and Nariño. Guinea pigs need far less room than pigs or cattle and reproduce extremely quickly. They can be raised even in cities, so they earn more income than many traditional livestock. Families buy and sell them at local markets and large municipal fairs.

  The meat is high in protein and low in fat and cholesterol, and is described as similar to rabbit or the dark meat of chicken. It may be fried, broiled or roasted, and city restaurants may serve it in a casserole or fricassee. Ecuadorians commonly eat sopa or locro de cuy, a soup. Cooking in an earth oven, called pachamanca or huatia, is also popular, and the dish is traditionally served with chicha, a corn beer.

  In the 1960s, Peruvian research universities, especially La Molina National Agrarian University, began experimental programs to breed larger guinea pigs. The La Molina variety grows fast and can weigh 3 kilograms. All the large breeds are known as cuy mejorados, and the pet breeds are cuy criollos. The three original Peruvian lines were the Peru, which weighed 800 grams by 2 weeks, the Andina and the Inti.

  In the 1990s and 2000s, La Molina University began exporting large-breed guinea pigs to Europe, Japan and the United States, hoping to raise consumption outside northern South America. Andean immigrants in New York City raise and sell guinea pigs for meat, and some South American restaurants in major American cities serve cuy as a delicacy. In the early 2000s, marketers also sought to expand consumption beyond South America.

  In West Africa, efforts have been made to promote guinea pig husbandry. The animals are more widespread there than generally known, because livestock statistics usually leave them out. Nobody knows when or where they reached Africa. They are widely distributed in Cameroon, found around cities and in rural South Kivu in the Democratic Republic of the Congo, and often kept by rural households in the Iringa Region of southwestern Tanzania.

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• 8. Test Subject

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  In the 17th century, the Italian biologists Marcello Malpighi and Carlo Fracassati dissected living guinea pigs to examine anatomical structures. In 1780, Antoine Lavoisier used one in experiments with the calorimeter, a device for measuring heat production. In the late 19th century, guinea pigs played a major role in establishing germ theory through the experiments of Louis Pasteur, Emile Roux and Robert Koch.

  On the 9th of March 1961, the USSR launched guinea pigs into orbit aboard the Sputnik 9 biosatellite, and they were recovered successfully. China launched and recovered a biosatellite carrying guinea pigs in 1990.

  About 2.5 million guinea pigs were used each year in the United States for research in the 1960s. By the mid-1990s, that number had fallen to about 375,000. As of 2007, they made up about 2 percent of all laboratory animals. Mice and rats have largely replaced them, partly because research into guinea pig genetics lagged behind that of other rodents. The geneticists W. E. Castle and Sewall Wright did contribute, especially on coat color. The guinea pig genome was sequenced in 2008 as part of the Mammalian Genome Project, but its sequence scaffolds have not been assigned to chromosomes.

  The guinea pig was used most in research and diagnosis of infectious diseases. Common uses included identifying brucellosis, Chagas disease, cholera, diphtheria, foot-and-mouth disease, glanders, Q fever, Rocky Mountain spotted fever and various strains of typhus. Because human tuberculosis bacteria infect them easily, they are still frequently used to diagnose tuberculosis. In the past they were widely used to standardize vaccines and antiviral agents, and to study anaphylaxis, the extreme allergic reaction.

  Scurvy research owes them a great debt. In 1907, researchers accidentally discovered that scurvy could be induced in guinea pigs. By 1932, the animals had helped prove the chemical structure of the "scorbutic factor," and the guinea pig model proved crucial to vitamin C research.

  Complement, an important component for serology, was first isolated from guinea pig blood. Guinea pigs have an unusual insulin mutation, with insulin at a level 10 times that found in other mammals. This may help regulate growth, a role usually played by growth hormone. They are suitable for producing anti-insulin antibodies and are models for juvenile diabetes. Because pregnancy toxemia is so frequent, they also serve as models for pre-eclampsia in women. Their placenta resembles the human one, and their gestation divides into trimesters like the stages of human fetal development.

  Most laboratory strains are outbred. The two main ones are the Hartley and the Dunkin-Hartley, both English and albino, though pigmented strains exist. Of the inbred strains, the two still used with any frequency are Strain 2 and Strain 13, named by Sewall Wright. Hairless breeds have been used since the 1980s, particularly in skin studies. A hairless, immunodeficient breed arose from a spontaneous mutation in Hartley stock at the Eastman Kodak Company in 1979. An immunocompetent hairless breed was identified by the Institute Armand Frappier in 1978, and Charles River Laboratories has reproduced it for research since 1982. Cavy fanciers then began acquiring hairless animals, and the pet versions are called skinny pigs.

  In English, "guinea pig" became a metaphor for any experimental subject. The earliest examples cited by the Oxford English Dictionary date from 1913 and 1920. In 1933, Consumers' Research founders F. J. Schlink and Arthur Kallet published 100,000,000 Guinea Pigs, extending the metaphor to consumer society. It became a national bestseller in the United States and spurred the growth of the consumer protection movement.

  During World War II, the Guinea Pig Club was founded at Queen Victoria Hospital in East Grinstead, Sussex, England. It was a social club and mutual support network for the patients of plastic surgeon Archibald McIndoe, who underwent previously untested reconstruction procedures. The word later took on a darker meaning. In 1970, the Czech author Ludvik Vaculik used it as the title of his novel The Guinea Pigs, an allegory for Soviet totalitarianism.

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