Guinea pig facts: surprising things about guinea pigs

10 fun facts about guinea pigs

If you only read one list, make it this one.

1. They're not pigs, and not from Guinea. Purdue's vet hospital says one story is that British sailors sold them in the 1600s for a guinea, an old English coin.
2. The pet guinea pig doesn't exist in the wild. The MSD Vet Manual says Cavia porcellus is a domestic species; its wild relatives live on the grassy plains of South America.
3. They can't make vitamin C. Like people, they have to eat it every day, and they can only store it for a short time (RSPCA).
4. Their teeth never stop growing. All 20 of them, says the MSD Vet Manual, which is why hay matters so much.
5. They eat some of their own droppings. Guinea pigs make two kinds, and eat the soft ones straight from their bottom. The RSPCA says this is essential to their diet.
6. Babies are born ready to go. Pups arrive furred, eyes open, teeth through, and start eating solid food within hours (Purdue).
7. They popcorn. Happy guinea pigs leap, twist and hop in the air, especially young ones (MSD, VCA).
8. They barely sleep. The RSPCA says they're active up to 20 hours a day, napping in short bursts.
9. They have different numbers of toes front and back. Four on each front foot, three on each back foot (MSD).
10. They have the longest pregnancy of any rodent. Purdue gives 63 to 68 days; the MSD Vet Manual gives a wider 59 to 72.

Where do guinea pigs come from?

South America. The MSD Vet Manual says guinea pigs belong to a rodent family native to that continent, and Purdue places their origins on its high plains. Their wild relatives graze on grasses and leaves, and the RSPCA says wild guinea pigs live in family groups of 5 to 10, sometimes joining into larger colonies.

• VCA says guinea pigs became popular pets in the early 16th century, and are also bred for shows in many colours and coat types.
• Show breeders and clubs call them cavies, from the scientific name Cavia porcellus.
• In the US the American Rabbit Breeders Association recognises 13 cavy breeds; the MSD Vet Manual says there are at least 13. See our guinea pig breeds guide.
• Males are boars, females are sows and babies are pups.

Guinea pig body facts

Heat is the fact that matters most here. Purdue warns heat stroke can kill a guinea pig within minutes, so a sunny window or a hot conservatory is dangerous. Our guinea pig temperature guide explains how to keep them comfortable.

Guinea pig teeth and food facts

• All 20 teeth are "open rooted", growing throughout life (MSD). Chewing hay grinds them down to the right length (RSPCA).
• If a guinea pig breaks a front tooth, Purdue says it usually grows back in about 2 to 3 weeks, though the opposite tooth may overgrow meanwhile.
• Woodgreen says each guinea pig should eat a pile of hay the size of itself every day.
• Once a bag of pellets is opened, its vitamin C content halves within three months (Woodgreen), so small bags are better.
• Guinea pigs are strict plant-eaters. Lawnmower clippings make them ill, says the RSPCA, though fresh grass is good for them.
• The RSPCA lists bell peppers, parsley, cucumber and romaine lettuce among the vegetables they can eat often.

Our vitamin C guide and guinea pig diet guide turn these facts into a daily menu.

Guinea pig behaviour and sound facts

• They are vocal: squeaks, chirps and a purr-like chatter, says the MSD Vet Manual, and they use many sounds to talk to each other (VCA).
• When they sense danger they either freeze or make an explosive dash for cover (VCA).
• They are a prey species and need enough hiding places for every guinea pig at once (RSPCA).
• Groups form a pecking order, with some guinea pigs more dominant than others (RSPCA).
• They rarely bite when handled calmly (MSD), and Purdue says they can be trained.
• They feel pain but hide it, so they may suffer before you notice (RSPCA).
• They love to tunnel through pipes and deep hay (RSPCA).

Want to decode the noises? Our guides to guinea pig sounds and guinea pig behaviour explain what each one means.

Baby guinea pig facts

Facts you need to know before getting guinea pigs

These are the facts that matter most if you're thinking of keeping them as pets.

• They live 5 to 8 years, and PetMD says up to 14 has been recorded
• They must live with at least one other guinea pig (RSPCA)
• Rabbits are not suitable companions; rabbits may bully or injure them (RSPCA)
• They need vitamin C from food every day
• Hay should be available all the time (RSPCA)
• Long-haired breeds need grooming every day (RSPCA, Humane World)
• Allergies to guinea pigs come from proteins in saliva and urine, not hair, and hay can trigger allergies too (Humane World)
• They need a vet check at least once a year (RSPCA)

Our guide to guinea pigs as pets goes through each of these, and our guinea pig lifespan guide covers the life stages.

Guinea pig myths and facts

For the full picture of looking after them, see our complete guinea pig care guide.