All Species Wiki
Guinea pig
General Information
Universe Real Life
Aliases Domestic guinea pig
Domestic cavy
Classification Cavia porcellus
Species Type Guinea pig
Homeworld Earth
Environment Human homes
Intelligence Non-sapient
Biochemistry Carbon-based
Biological Information
Lifespan 4-8 years
Reproduction Sexual, viviparous
Average Weight Pet breeds: 700 and 1,200 g (1.5 and 2.6 lb)
Livestock breeds: 3 kilograms (6.6 lb)
Average Length 20 and 25 cm (8 and 10 in)
Locomotion Quadrupedal
Feeding Behavior Herbivorous
Prey Grass
Lineage Information
Related Species Brazilian guinea pig
Montane guinea pig
Cavia guianae
Cavia anolaimae
Shiny guinea pig
Greater guinea pig
Santa Catarina's guinea pig
Cultural Information
Leaders Humans
Sociocultral characteristics
Scientific Taxonomy
Planet Earth
Domain Eukaryota
Kingdom Animalia
Subkingdom Bilateria
Infrakingdom Deuterostomia
Phylum Chordata
Subphylum Vertebrata
Infraphylum Gnathostomata
Superclass Tetrapoda
Class Mammalia
Subclass Theria
Infraclass Placentalia
Superorder Euarchontoglires
Order Rodentia
Suborder Hystricomorpha
Infraorder Hystricognathi
Superfamily Caviomorpha
Family Caviidae
Subfamily Caviinae
Genus Cavia
Species C. porcellus
Other Information
Status Domesticated
Least Concern
Creator God (debated)

The guinea pig (Cavia porcellus), also called the cavy is a domesticated rodent commonly kept as pets by humans.


Guinea pigs are large for rodents; the common pet breeds weigh between 700 and 1,200 g (1.5 and 2.6 lb) when fully grown and measure between 20 and 25 cm (8 and 10 in) in length. Some livestock breeds weigh 3 kilograms (6.6 lb) when full grown. Pet breeds live an average of four to five years, but may live as long as eight years. According to Guinness World Records, as of 2006, the longest-lived guinea pig was 14 years, 10 months, and 2 weeks old. Most guinea pigs have fur, but one laboratory breed adopted by some pet owners, the skinny pig, is a mostly furless breed. Some breeds are long-fur breeds such as the Peruvian, the Silkie, and the Texel.

In the 1990s, a minority scientific opinion emerged proposing that caviomorphs such as guinea pigs, chinchillas, and degus are not actually rodents, and should be reclassified as a separate order of mammals (similar to the rodent-like lagomorphs which includes rabbits). Subsequent research using wider sampling restored the consensus among mammalian biologists regarding the current classification of rodents, including guinea pigs, as monophyletic.

Male and female guinea pigs do not differ in appearance apart from general size. The position of the anus is very close to the genitals in both sexes. Sexing animals at a young age must be done by someone who has been trained in the differences. Female genitals are distinguished by a "Y"-shaped configuration formed from a vulvar flap. While male genitals may look similar, with the penis and anus forming a similar shape, the penis will protrude if pressure is applied to the surrounding hair anterior to the genital region. The male's testes may also be visible externally from scrotal swelling.


Guinea pigs can learn complex paths to food, and can accurately remember a learned path for months. Their strongest problem-solving strategy is motion. While guinea pigs can jump small obstacles, they cannot jump very high. Most of them are poor climbers, and are not particularly agile. They startle easily, and when they sense danger either freeze in place for long periods, or run for cover with rapid, darting motions. Larger groups of startled guinea pigs "stampede", running in haphazard directions as a means of confusing predators. When happily excited, guinea pigs may (often repeatedly) perform little hops in the air (a movement known as "popcorning"), analogous to the ferret's war dance, and also similar to rabbit happy hops. Guinea pigs are also good swimmers, although they do not like being wet and infrequently need bathing.

Like many rodents, guinea pigs sometimes participate in social grooming, and they regularly self-groom. A milky-white substance is secreted from their eyes and rubbed into the hair during the grooming process. Groups of boars often chew each other's hair, but this is a method of establishing hierarchy within a group, rather than a social gesture. Dominance is also established through biting (especially of the ears), piloerection, aggressive noises, head thrusts, and leaping attacks. Non-sexual simulated mounting for dominance is also common among same-sex groups.

Guinea pig eyesight is not as good as that of a human in terms of distance and color, but they have a wider angle of vision (about 340°) and see in partial color (dichromacy). They have well-developed senses of hearing, smell, and touch.

Guinea pigs have developed a different biological rhythm from their wild counterparts, and have longer periods of activity followed by short periods of sleep in between. Activity is scattered randomly throughout the day; aside from an avoidance of intense light, no regular circadian patterns are apparent.

Guinea pigs do not generally thrive when housed with other species. Larger animals may regard guinea pigs as prey, though some dogs and cats can be trained to accept them. Opinion is divided over the cohousing of guinea pigs and rabbits. Some published sources say that guinea pigs and rabbits complement each other well when sharing a cage. However, rabbits have different nutritional requirements; as lagomorphs, they synthesize their own Vitamin C, so the two species will not thrive if fed the same food when housed together. Rabbits may also harbor diseases (such as respiratory infections from Bordetella and Pasteurella), to which guinea pigs are susceptible. Housing guinea pigs with other rodents such as gerbils and hamsters may increase instances of respiratory and other infections, and such rodents may act aggressively toward guinea pigs.


Vocalization is the primary means of communication between members of the species. These are the most common sounds made by the guinea pig:

  • A "wheek" is a loud noise, the name of which is onomatopoeic, also known as a whistle. An expression of general excitement, it may occur in response to the presence of its owner or to feeding. It is sometimes used to find other guinea pigs if they are running. If a guinea pig is lost, it may wheek for assistance
  • A bubbling or purring sound is made when the guinea pig is enjoying itself, such as when being petted or held. It may also make this sound when grooming, crawling around to investigate a new place, or when given food.
  • A rumbling sound is normally related to dominance within a group, though it can also come as a response to being scared or angry. In the case of being scared, the rumble often sounds higher and the body vibrates shortly. While courting, a male usually purrs deeply, swaying and circling the female in a behavior called rumblestrutting. A low rumble while walking away reluctantly shows passive resistance.
  • Chutting and whining are sounds made in pursuit situations, by the pursuer and pursuee, respectively.
  • A chattering sound is made by rapidly gnashing the teeth, and is generally a sign of warning. Guinea pigs tend to raise their heads when making this sound.
  • Squealing or shrieking is a high-pitched sound of discontent, in response to pain or danger.
  • Chirping, a less common sound, likened to bird song, seems to be related to stress or discomfort, or when a baby guinea pig wants to be fed. Very rarely, the chirping will last for several minutes.

Living environment[]

Domestic guinea pigs generally live in cages, although some owners of large numbers of cavies dedicate entire rooms to their pets. Wire mesh floors can cause injury and may be associated with an infection commonly known as bumblefoot (ulcerative pododermatitis), so cages with solid bottoms, where the animal walks directly on the bedding, are typically used. Large cages, which allow for adequate running space, can be constructed from wire grid panels and plastic sheeting, a style known as C&C, or "cubes and coroplast".

Red cedar (Eastern or Western) and pine, both softwoods, were commonly used as bedding, but now these materials are believed to contain harmful phenols (aromatic hydrocarbons) and oils. Bedding materials made from hardwoods (such as aspen), paper products, and corn cobs are alternatives. Guinea pigs tend to be messy; they often jump into their food bowls or kick bedding and feces into them, and their urine sometimes crystallizes on cage surfaces, making it difficult to remove. After its cage has been cleaned, a guinea pig typically urinates and drags its lower body across the floor of the cage to mark its territory. Male guinea pigs may mark their territory in this way when they are put back into their cages after being taken out.

Guinea pigs thrive in groups of two or more; groups of sows, or groups of one or more sows and a neutered boar are common combinations, but boars can sometimes live together. Guinea pigs learn to recognize and bond with other individual pigs, and tests show that a boar's neuroendocrine stress response to a strange environment is significantly lowered in the presence of a bonded female, but not with unfamiliar females. Groups of boars may also get along, provided their cage has enough space, they are introduced at an early age, and no females are present. In Switzerland, where keeping a guinea pig without a companion is illegal, a service to rent guinea pigs (to temporarily replace a dead cage-mate) is available. Sweden has similar laws against keeping a guinea pig by itself.


Latin name[]

The scientific name of the common species is Cavia porcellus, with 'porcellus' being Latin for "little pig". Cavia is New Latin; it is derived 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 çavia (now savia), which is itself derived from the Tupi word saujá, meaning rat.

Guinea pig[]

The origin of "guinea" in "guinea pig" is hard to explain. One proposed explanation is that the animals were brought to Europe by way of Guinea, leading people to think they had originated there. "Guinea" was also frequently used in English to refer generally to any far-off, unknown country, so the name may simply be a colorful reference to the animal's exotic origins.

Another hypothesis suggests the "guinea" in the name is a corruption of "Guiana", an area in South America. A common misconception is that they were so named because they were sold for the price of a guinea coin. This hypothesis is untenable, because the guinea was first struck in England in 1663, and William Harvey used the term "Ginny-pig" as early as 1653. Others believe "guinea" may be an alteration of the word coney (rabbit); guinea pigs were referred to as "pig coneys" in Edward Topsell's 1607 treatise on quadrupeds.

How the animals came to be called "pigs" is not clear. They are built somewhat like pigs, with large heads relative to their bodies, stout necks, and rounded rumps with no tail of any consequence; some of the sounds they emit are very similar to those made by pigs, and they spend a large amount of time eating. They can survive for long periods in small quarters, like a 'pig pen', and were easily transported by ship to Europe.

Other languages[]

Guinea pigs are called quwi or jaca in Quechua and cuy or cuyo (plural cuyes, cuyos) in the Spanish of Ecuador, Peru, and Bolivia.

The animal's name alludes to pigs in many European languages. The German word for them is Meerschweinchen, literally "little sea pig", in Polish they are called świnka morska, in Hungarian as tengerimalac, and in Russian as морская свинка. This derives from the Middle High German name merswin. This originally meant "dolphin" and was used because of the animals' grunting sounds (which were thought to be similar).

Many other, possibly less scientifically based, explanations of the German name exist. For example, sailing ships stopping to reprovision in the New World would pick up stores of guinea pigs, which provided an easily transportable source of fresh meat. The French term is cochon d'Inde (Indian pig), or cobaye; the Dutch called it Guinees biggetje (Guinean piglet), or cavia (in some Dutch dialects it is called Spaanse rat); and in Portuguese, the guinea pig is variously referred to as cobaia, from the Tupi word via its Latinization, or as porquinho da Índia (little Indian pig). This association with pigs is not universal among European terms; for example, the common word in Spanish is conejillo de Indias (little rabbit of the Indies).

The Chinese refer to the animal as 豚鼠 (túnshǔ, 'pig mouse'), and sometimes as 荷蘭豬 (hélánzhū, 'Netherlands pig') or 天竺鼠 (tiānzhúshǔ, 'Indian mouse'). The Japanese word for guinea pig is モルモット (morumotto), which derives from the name of another mountain-dwelling rodent, the marmot. This is what the guinea pigs were called by Dutch traders, who first brought them to Nagasaki in 1843. The other, and less common, Japanese word for guinea pig, using kanji, is 天竺鼠 (てんじくねずみ or tenjiku-nezumi), which literally translates as 'India rat'.


The guinea pig's natural diet is grass; their molars are particularly suited for grinding plant matter and grow continuously throughout their life. Most mammals that graze are large and have a long digestive tract; guinea pigs have much longer colons than most rodents, but they must also supplement their diet by eating their feces (coprophagy) . However, they do not consume all their feces indiscriminately, but produce special soft pellets, called cecotropes (or caecal pellets), which recycle B vitamins, fiber, and bacteria required for proper digestion. The cecotropes are eaten directly from the anus, unless the guinea pig is pregnant or obese. They share this behaviour with rabbits. In geriatric boars or sows (rarely in young ones), the muscles which allow the softer pellets to be expelled from the anus can become weak. This creates a condition known as fecal impaction, which prevents the animal from redigesting cecotropes even though harder pellets may pass through the impacted mass. The condition may be temporarily alleviated by a human carefully removing the impacted feces from the anus.

Guinea pigs benefit from a diet of fresh grass hay, such as timothy hay, in addition to food pellets which are often based on timothy hay. Alfalfa hay is also a popular food choice and most guinea pigs will eat large amounts of alfalfa when offered it, though some controversy exists over offering alfalfa to adult guinea pigs. Some pet owners and veterinary organizations have advised that, as a legume rather than a grass hay, alfalfa consumed in large amounts may lead to obesity, as well as bladder stones from the excess calcium in all animals except for pregnant and very young guinea pigs. However, published scientific sources mention alfalfa as a food source that can replenish protein, amino acids, and fiber.

Like humans, but unlike most other mammals, guinea pigs cannot synthesize their own vitamin C and must obtain this vital nutrient from food. If guinea pigs do not ingest enough vitamin C, they can suffer from potentially fatal scurvy. Guinea pigs require about 10 mg of vitamin C daily (20 mg if pregnant), which can be obtained through fresh, raw fruits and vegetables (such as broccoli, apple, cabbage, carrot, celery, and spinach) or through dietary supplements or by eating fresh pellets designed for guinea pigs, if they have been handled properly. Healthy diets for guinea pigs require a complex balance of calcium, magnesium, phosphorus, potassium, and hydrogen ions; but adequate amounts of vitamins A, D, and E are also necessary.

Poor diets for guinea pigs have been associated with muscular dystrophy, metastatic calcification, difficulties with pregnancy, vitamin deficiencies, and teeth problems. Guinea pigs tend to be fickle eaters when it comes to fresh fruits and vegetables after having learned early in life what is and is not appropriate to consume, and their eating habits may be difficult to change after maturity. They do not respond well to sudden changes in their diet and they may stop eating and starve rather than accept new food types. A constant supply of hay is generally recommended, as guinea pigs feed continuously and may develop bad habits if food is not present, such as chewing on their hair. Because their teeth grow constantly (as do their nails, like humans), they routinely gnaw on things, lest their teeth become too large for their jaw (a common problem in rodents). Guinea pigs chew on cloth, paper, plastic, and rubber, if they are available.

A number of plants are poisonous to guinea pigs, including bracken, bryony, buttercup, charlock, deadly nightshade, foxglove, hellebore, hemlock, lily of the valley, mayweed, monkshood, privet, ragwort, rhubarb, speedwell, toadflax (both Linaria vulgaris and Linaria dalmatica), and wild celery. Additionally, any plant which grows from a bulb (e.g., tulip or onion) is normally considered poisonous, as well as ivy and oak tree leaves.


Males (boars) reach sexual maturity in 3–5 weeks. Similarly, females (sows) can be fertile as early as 4 weeks old, and can carry litters before they are fully-grown adults. A sow is able to breed year-round (with spring being the peak). A sow can have as many as five litters in a year, but six is theoretically possible. Unlike the offspring of most rodents, which are altricial at birth, newborn cavy pups are precocial, and are well-developed with hair, teeth, claws, and partial eyesight. The pups are immediately mobile and begin eating solid food immediately, though they continue to suckle. Sows can once again become pregnant 6–48 hours after giving birth, but it is not healthy for a female to be constantly pregnant.

The gestation period lasts from 59 days (1.9 months) to 72 days (2.4 months), with an average of 63–68 days. Because of the long gestation period and the large size of the pups, pregnant sows may become large and eggplant-shaped, although the change in size and shape varies depending upon the size of the litter. Litter size ranges from one to six, with three being the average; the largest recorded litter size is 9. The guinea pig mother only has two nipples, but she can readily raise the more average-sized litters of 2 to 4 pups. In smaller litters, difficulties may occur during labour due to oversized pups. Large litters result in higher incidences of stillbirth, but because the pups are delivered at an advanced stage of development, lack of access to the mother's milk has little effect on the mortality rate of newborns.

Cohabitating females assist in mothering duties if lactating; guinea pigs practice alloparental care, in which a sow may adopt the pups of another. This might take place if the original parents die or are for some reason separated from them. This behavior is common and is seen in many other animal species such as the elephant.

Toxemia of pregnancy (hypertension) is a common problem and kills many pregnant females. Signs of toxemia include: anorexia (loss of appetite), lack of energy, excessive salivation, a sweet or fruity breath odor due to ketones, and seizures in advanced cases. Pregnancy toxemia appears to be most common in hot climates. Other serious complications during pregnancy can include a prolapsed uterus, hypocalcaemia, and mastitis.

Females that do not give birth may develop an irreversible fusing or calcified cartilage of the pubic symphysis, a joint in the pelvis, which may occur after six months of age. If they become pregnant after this has happened, the birth canal may not widen sufficiently, which may lead to dystocia and death as they attempt to give birth.

Health problems[]

Common ailments in domestic guinea pigs include respiratory tract infections, diarrhea, scurvy (vitamin C deficiency, typically characterized by sluggishness), abscesses due to infection (often in the neck, due to hay embedded in the throat, or from external scratches), and infections by lice, mites, or fungus.

Mange mites (Trixacarus caviae) are a common cause of hair loss, and other symptoms may also include excessive scratching, unusually aggressive behavior when touched (due to pain), and, in some instances, seizures. Guinea pigs may also suffer from "running lice" (Gliricola porcelli), a small, white insect that can be seen moving through the hair; their eggs, which appear as black or white specks attached to the hair, are sometimes referred to as "static lice". Other causes of hair loss can be due to hormonal upsets caused by underlying medical conditions such as ovarian cysts.

Foreign bodies, especially small pieces of hay or straw, can become lodged in the eyes of guinea pigs, resulting in excessive blinking, tearing, and in some cases an opaque film over the eye due to corneal ulcer. Hay or straw dust can also cause sneezing. While it is normal for guinea pigs to sneeze periodically, frequent sneezing may be a symptom of pneumonia, especially in response to atmospheric changes. Pneumonia may also be accompanied by torticollis and can be fatal.

Because the guinea pig has a stout, compact body, it more easily tolerates excessive cold than excessive heat. Its normal body temperature is 101–104 °F (38–40 °C), so its ideal ambient air temperature range is similar to a human's, about 65–75 °F (18–24 °C). Consistent ambient temperatures in excess of 90 °F (32 °C) have been linked to hyperthermia and death, especially among pregnant sows. Guinea pigs are not well suited to environments that feature wind or frequent drafts, and respond poorly to extremes of humidity outside of the range of 30–70%.

Guinea pigs are prey animals whose survival instinct is to mask pain and signs of illness, and many times health problems may not be apparent until a condition is severe or in its advanced stages. Treatment of disease is made more difficult by the extreme sensitivity guinea pigs have to most antibiotics, including penicillin, which kill off the intestinal flora and quickly bring on episodes of diarrhea and in some cases, death.

Similar to the inherited genetic diseases of other breeds of animal (such as hip dysplasia in canines), a number of genetic abnormalities of guinea pigs have been reported. Most commonly, the roan coloration of Abyssinian guinea pigs is associated with congenital eye disorders and problems with the digestive system. Other genetic disorders include "waltzing disease" (deafness coupled with a tendency to run in circles), palsy, and tremor conditions.