Guinea pig

Quick Take

• Guinea pigs rarely close their eyes, and this is true even when they're asleep. The reason reveals something surprising about how they've survived for thousands of years. See this sleeping quirk →
• These animals were never meant to be pets. Their path from food source to beloved household companion involves a twist most owners don't know. Trace their unlikely origins →
• One species of Guinea Pig is on the brink of extinction, yet almost nobody talks about it. Meet the critically endangered species →
• Domestic Guinea Pigs can live dramatically longer than their wild relatives, provided that owners know one critical dietary requirement. Discover the critical diet requirement →

Due to their small size and ease of care, Guinea Pigs have been farmed by local people for food for thousands of years. Their calm and docile nature has made them one of the most commonly kept household pets worldwide, and they now come in a wide variety of sizes and colors due to selective breeding.

Classification and Evolution

The Guinea Pig (also known as a Cavy) is a small type of rodent that is found inhabiting the Central Andes Mountains in South America.

Named after the price they commanded in 16th-century England — one guinea coin — and ‘pig’ for resembling their short and stout bodies, Guinea Pigs have been domesticated by people for over 7,000 years, as they were originally kept and farmed as a source of food throughout much of their natural range in South America.

With the arrival of the Spanish on the continent in the 1500s, Guinea Pigs were more selectively bred to be kept as pets and are today one of the most common domestic household pets, loved by people all around the world for their calm and docile nature and small size.

Today there are six species of Guinea Pig found worldwide, and over forty different breeds of domestic Guinea Pig bred all around the world.

Guinea Pig Species

• Domestic guinea pig: Cavia porcellus (the common pet)
• Brazilian guinea pig: Cavia aperea
• Shiny guinea pig: Cavia fulgida
• Intermediate guinea pig: Cavia intermedia
• Greater guinea pig: Cavia magna
• Montane guinea pig: Cavia tschudi

Different Breeds of Domestic Guinea Pig

• Peruvian guinea pig
• Skinny pig
• Abyssinian guinea pig
• American Guinea Pig
• Teddy guinea pig
• Sheltie guinea pig
• American Crested
• English Crested Guinea Pig
• Rex guinea pig
• Cuy
• Texel guinea pig
• Himalayan guinea pig
• Satin

Anatomy and Appearance

Guinea Pigs have a very distinctive appearance with small, stout bodies with no tail and a large head with large and alert eyes.

They have strong, short legs with four toes on their front feet and three on the back, all with sharp claws that help them when they are burrowing and scrabbling around in the wild. Like other species of rodents, Guinea Pigs have an exceptional sense of smell and hearing that, coupled with their long whiskers, gives them a heightened awareness of changes in their surroundings so they are able to detect predators more effectively.

Guinea Pigs have long, coarse fur that in the wild is grey, brown, or black in color. Domestic Guinea Pigs, however, can be found in a variety of different colors with different hair lengths and smoothness. One of the most characteristic features of Guinea Pigs (and indeed all rodents compared to other mammal species) is the four large incisors at the front of their mouths.

These teeth are long and curved and grow continuously, but only the fronts are protected by a hard enamel coating. The backs of their teeth are made of a softer material that corrodes easily with constant gnawing, which allows Guinea Pigs to keep their teeth as sharp as possible at all times.

Distribution and Habitat

Guinea Pigs are found in a variety of habitats throughout the Central Andes Mountain Range in South America, from Venezuela in the north to Patagonia, excluding the more tropical regions of the Amazon Basin. They prefer grasslands, swamps, and rocky hillsides in areas with plenty of vegetation but that are predominantly open so they are more easily able to locate the threat of approaching predators.

Guinea Pigs are also found inhabiting regions of varying altitudes from low elevations up to around 16,000 feet (5,000 meters) above sea level, provided they have good access to food and in areas that are suitable for burrowing.

Although they are capable of digging their own burrows, Guinea Pigs often prefer to move into abandoned burrows created by other small mammals or reside in rocky crevices on the hillside.

Behavior and Lifestyle

Guinea Pigs are crepuscular animals that are most active during dawn and dusk. This is thought to be due to lower levels of activity from predatory species that struggle during these hours with the drastic changes in light. They are highly sociable, living together in small groups of up to 10 individuals. Guinea Pig groups have a well-established hierarchy that is ruled by a single male and female, competition for these roles can often lead to fatalities.

Guinea Pigs are highly vocal, communicating with each other using an extensive range of vocalizations including chirps, squeaks, and burbles to show excitement or to warn others of approaching danger. They are also known to communicate by smell, excreting odors through scent glands on their bodies.

Guinea Pigs settle in burrows close to good sources of food with their small groups but often have their own individual nests where they sleep and hide.

Pets

Guinea Pigs make excellent pets due to their playful, social nature. They also live for several years — longer than most other rodents — so you can enjoy them for longer than other pet rodents.

As noted above, Guinea Pigs are highly vocal and use their voice to express their personality. They make an excellent first pet for a child as they are fun to play with and require minimal maintenance.

If you’re considering a Guinea Pig for a pet, or already have one, be sure to check out our guide to keeping guinea pigs as pets.

Reproduction and Life Cycles

Guinea pigs are able to breed when they are very young, with females reaching sexual maturity as early as 4 to 6 weeks of age and males as early as 3 to 5 weeks. In the wild, there is no distinct breeding season, as they are known to produce litters of young all year round. After a relatively long gestation period of between 58 and 72 days, the female Guinea Pig (known as a sow) gives birth to as many as 13 young, although the average in the wild is closer to three or four.

Guinea Pig pups are very well developed at birth and, unlike a number of other rodent species, are born with their long fur. They suckle on their mother’s milk for the first 21 days but can begin grazing independently within the group on solid foods by the end of their first week. During the course of a year, a female Guinea Pig may give birth to up to five litters. Guinea Pigs have a lifespan in the wild of three or four years.

Domestic Guinea Pigs are known to live a great deal longer than their wild counterparts, normally reaching the age of 6, although some live even longer — the oldest recorded Guinea Pig reached 15 years old.

Diet and Prey

Guinea Pigs are herbivorous animals, which means that they only eat plant material to gain all the nutrients they need to survive. Grasses, leaves, seeds, bark, and flowers make up the majority of their diets on the mountain slopes in South America. Guinea Pigs are constantly grazing rather than eating large amounts of food in one go, which they primarily do during twilight hours when fewer predators are around.

They have well-trodden paths that they use to get between their food sources and their burrows and can often be seen in a mass gathering when a number of Guinea Pig groups are in the same area where food is in abundance. The natural diet of Guinea Pigs is very high in vitamin C, so domesticated pet Guinea Pigs must be provided with a diet that contains plenty of it.

Along with grasses, hay, and vegetables, domestic Guinea Pigs are often supplemented with special nuggets that contain plenty of the nutrients that they need to survive effectively and healthily.

Predators and Threats

Due to their small size and instinct to freeze before quickly escaping back to their burrows, Guinea Pigs are preyed upon by several other animal species throughout their mountain habitats. Mammals including weasels and birds of prey are the main predators of wild Guinea Pigs, along with domesticated dogs and cats in regions where they reside close to human populations.

Although some populations are heavily affected by habitat degradation, Guinea Pigs are fairly adaptable animals that are able to inhabit areas where other species may not thrive. They are also still captured and farmed for food by people throughout much of their natural range in South America.

Some populations have also been known to be severely affected by diseases from other animals in places where they are coming into regular and close contact with other domestic species.

Interesting Facts and Features

Guinea Pigs are known to exhibit a behavior known as “popcorning” when they become excited. Mostly displayed by young Guinea Pigs, they are able to jump into the air whilst running and quickly turn around in order to jump again in excitement.

Oddly, Guinea Pigs very rarely close their eyes, even while sleeping. Most commonly observed with domestic animals, it is thought to be a protective trait that enables them to stay as alert as possible at all times.

Interestingly, it has been reported that Guinea Pigs have been used by doctors to help identify illnesses in people. By placing the Guinea Pig on the person, the animal will give a little squeak when it detects the location of the problem.

Relationship with Humans

The sweet and chatty temperament of Guinea Pigs has led to them becoming a favorite pet for children, who are able to look after them with relative ease (provided they are overseen by a responsible adult). Their placid nature, however, has also sadly led to them being widely used in laboratory experiments for many years.

Conservation Status and Life Today

Today, four of the five Guinea Pig species found throughout South America are listed by the IUCN as animals that are of Least Concern of becoming extinct in the wild in the near future.

Despite declining populations in specific regions, their ability to breed effectively across a wide variety of changing habitats has kept Guinea Pig numbers relatively stable.

The exception to this is the Santa Catarina’s Guinea Pig, which is found in one area of Brazil. With only 24 to 60 individuals thought to remain in the wild and only in one small area, they have been listed as Critically Endangered in their natural environment.