A cavy is a South American rodent belonging to the family Caviidae. The most famous cavy by far is the domestic guinea pig, but the family includes 14 species across five genera, from tiny wild cavies that forage in grasslands to the long-legged Patagonian mara. If you’ve seen the word “cavy” used by breeders or pet owners, they’re almost always talking about the guinea pig, whose scientific name is Cavia porcellus.
The Caviidae Family
Caviidae splits into two subfamilies. The Caviinae contains the animals most people picture when they hear “cavy”: the genera Cavia (guinea pigs and their wild relatives), Microcavia (small desert-dwelling cavies), Galea (yellow-toothed cavies), and Kerodon (rock cavies). The second subfamily, Dolichotinae, contains Dolichotis, the Patagonian maras, which look more like long-eared hares than typical rodents. Capybaras, the world’s largest rodents, are also closely related and sometimes placed within Caviidae, though taxonomists have shifted them in and out of the family over the years.
All caviids are native to South America. Wild cavies occupy habitats ranging from Andean grasslands to rocky outcrops in Brazil. Microcavia species climb trees to reach leaves and fruit, while Cavia species stay on the ground and eat grasses. Kerodon, the rock cavy, is kept as both a pet and a food source in parts of South America, though it’s far less common worldwide than the domestic guinea pig.
Domestication History
Guinea pigs have one of the longest domestication histories of any pet. Archaeological evidence from the Central Andes places their domestication somewhere between 6000 and 2000 BC, with southern Peru and northern Chile as the most likely origin point. The wild ancestor is Cavia tschudii, a species still found in South American highlands. People initially raised them for meat, and guinea pig remains a traditional protein source in Andean countries today.
There’s also evidence of a second, independent domestication event. Skeletal remains from the Sabana de Bogotá in Colombia suggest people were using cavies as early as 9000 BC, and recent genetic analysis supports the idea that Colombian highland populations were domesticated separately from those in Peru. After these initial domestications, guinea pigs eventually made their way to Europe, where breeders developed the laboratory and pet breeds familiar today.
Physical Traits
Domestic guinea pigs are compact, round-bodied rodents weighing roughly 1.8 to 2.2 pounds. They have no visible tail, which distinguishes them from most other rodents at a glance. Their front feet have four toes and their back feet have three, each tipped with a sharp claw that grows continuously and needs occasional trimming in captivity. Coat types vary widely among breeds, from the short, smooth fur of the American guinea pig to the long, flowing hair of Peruvian and Silkie breeds.
Wild cavies look noticeably different from their domestic counterparts. They tend to be leaner, with more uniform brown or gray-brown coats that provide camouflage. Domestication has also changed their temperament at a biological level. Compared to wild Cavia aperea, domestic guinea pigs are significantly less aggressive, more socially tolerant, and far less vigilant about their surroundings. Their stress response systems are markedly less reactive, which is part of why they adapt well to living in homes. Male domestic guinea pigs also have higher reproductive hormone levels than wild males, a common pattern across domesticated species.
Behavior and Vocalizations
Cavies are social animals that communicate through a surprisingly rich vocabulary of sounds. The most recognizable is “wheeking,” a high-pitched whistle that usually means your guinea pig wants food. It’s often triggered by the sound of a refrigerator opening or a plastic bag rustling. “Chutting,” a soft clucking sound, signals contentment, and you’ll hear it during relaxed interactions or while a guinea pig explores its surroundings. “Bubbling” is even quieter and typically accompanies “pancaking,” where the animal lies completely flat with eyes closed in total relaxation.
“Rumble strutting” is one of the more entertaining behaviors. A guinea pig shifts its weight side to side while walking, sometimes puffing up its fur to look larger. This is a dominance display. A different type of rumbling, where the animal freezes and goes wide-eyed, signals that something has startled it. Teeth chattering means annoyance or anxiety, whining communicates discomfort (and in softer forms can indicate pain), and shrieking is an unmistakable sign of fear or acute pain. Some guinea pigs also “chirp,” producing a bird-like sound that’s thought to be an alert signal. Not all guinea pigs chirp, and researchers still debate its exact meaning.
Diet and Vitamin C
Like humans and only a handful of other mammals, cavies cannot produce their own vitamin C. This makes them uniquely vulnerable to scurvy if their diet falls short. The minimum to prevent scurvy is only about 2 mg per day, but the amount needed for tissue saturation and overall health is closer to 25 to 30 mg per day. Most guinea pig care guides recommend providing vitamin C through fresh vegetables like bell peppers, leafy greens, and small amounts of fruit, supplemented by high-quality timothy hay-based pellets fortified with vitamin C.
Hay should make up the bulk of a cavy’s diet. It provides the fiber needed to keep their continuously growing teeth worn down and their digestive system functioning. Fresh water, unlimited hay, a measured portion of pellets, and a daily serving of fresh vegetables form the core of a healthy feeding routine.
Lifespan and Reproduction
The average lifespan of a pet guinea pig is about four years. A large study of British pet guinea pigs confirmed a mean lifespan of 4.02 years, though some sources cite ranges of five to seven years for well-kept indoor animals, and individual guinea pigs occasionally reach eight. Genetics, diet, and housing quality all influence longevity.
Guinea pigs have an unusually long gestation for rodents, averaging 68 to 72 days. Litters typically contain two to three pups, with a range of one to six. Unlike many rodent species, guinea pig pups are born fully furred with open eyes and can eat solid food within days, though they still nurse for the first few weeks.
Housing Requirements
Guinea pigs need more space than most people expect. For a single animal, the bare minimum is 7.5 square feet (roughly 30 by 36 inches), but bigger enclosures lead to happier, more active pets. A pair does best with at least 10.5 square feet. Three guinea pigs need a minimum of 10.5 square feet, with 13 preferred, and four guinea pigs should have at least 13 square feet. Sides should be at least 12 inches high. Open-top enclosures work fine as long as other household pets can’t access them.
Avoid glass aquariums, which trap humidity and ammonia, and wire-bottom cages, which hurt their feet. Paper-based bedding, layered two to three inches deep, is the safest substrate. Cedar and pine shavings release chemicals that can damage a guinea pig’s respiratory system and should not be used. Since cavies are highly social, keeping at least two together is strongly recommended. Same-sex pairs or small groups generally do well, especially if introduced at a young age.