Guinea Pig Care 101: Everything New Owners Need to Know

Guinea pigs are social, long-lived and easy to get wrong in the same few ways: cages that are too small, too little hay, and not enough vitamin C. This guide covers housing, diet, companionship and the signs that mean a vet visit, with products such as Kaytee Timothy Hay, Oxbow Essentials pellets and Carefresh Bedding mentioned where they fit.

How this guide was put together: we compared manufacturer specifications, labels, published guidance and reported owner experience. We have not tested these products ourselves, and nothing here is veterinary advice.

Cage size: the number that matters most

Rescue and welfare guidance commonly puts the minimum at around 7.5 square feet of floor for a single guinea pig and around 10.5 for a pair, and more is always better. Almost every cage sold in a pet shop as a guinea pig cage is below that.

Two things follow. Floor area beats levels — guinea pigs are ground animals and barely use height, unlike rats. And guinea pigs must never be kept alone, so you are always sizing for at least two.

If the cage you can afford is smaller than the animals need, the answer is a connected run or a C&C grid cage, not fewer square feet.

Vitamin C: the thing that quietly kills guinea pigs

Guinea pigs, like humans and unlike almost every other pet, cannot synthesise vitamin C. They need it from the diet every single day.

Deficiency causes scurvy: lethargy, a rough staring coat, painful swollen joints, reluctance to move, poor wound healing and eventually death. It is entirely preventable and still turns up regularly at exotics vets.

Three practical points that matter more than the brand of pellet:

Hay is the diet, not the bedding

Unlimited grass hay should be the great majority of what a guinea pig eats, every day, for life. Pellets are a supplement to hay, not the other way round.

Two reasons, both serious. Guinea pigs have continuously growing teeth, and hours a day grinding abrasive long-strand hay is what wears them at the rate they grow — without enough, molars form sharp spurs that cut the cheek and tongue. And guinea pig digestion depends on a constant flow of long-strand fibre; when that stops, the gut slows.

Timothy hay for adults. Alfalfa is a legume hay much higher in calcium, right for growing, pregnant or nursing pigs and associated with bladder stones as an adult staple.

Feeding: what goes in the bowl each day

This section folds in our former standalone feeding guide. The nutrition figures follow the Merck Veterinary Manual.

How much vitamin C. The Merck Veterinary Manual gives a maintenance requirement of around 10 mg per kg of body weight per day, rising to around 30 mg/kg for pregnant sows. Deficiency develops within weeks.

Hay, unlimited. Timothy is the usual adult staple; orchard grass and meadow hay are good alternatives for variety. Alfalfa is kept for young, pregnant or nursing guinea pigs.

Pellets, measured. Plain, uniform pellets fortified with stabilised vitamin C, fed as a measured daily amount (around 1/8 cup per adult is a common guide) rather than an unlimited bowl. Check the milling or best-before date on the bag.

Fresh vegetables, daily. Around a cup of mixed vegetables per guinea pig per day is a common guide. Bell pepper for vitamin C; romaine, coriander (cilantro) and parsley for variety. Feed higher-calcium greens such as kale and parsley in moderation, and fruit only as an occasional treat.

Water, always. Clean water in a bottle or heavy bowl, changed daily.

Foods to avoid. Commonly listed as unsafe: potato and its leaves, onion and garlic, avocado, chocolate, rhubarb and houseplants. Avoid seeds, nuts, dairy and bread, and check any new food against a reliable list before offering it.

If you are not sure the diet supplies enough vitamin C, a chewable vitamin C tablet made for small animals is more reliable than water additives. Ask your vet about the dose.

When in doubt, more hay.

Signs that mean a vet, not a wait-and-see

Guinea pigs are prey animals and hide illness until they are genuinely unwell. By the time a guinea pig looks ill, it has usually been ill for a while.

Go to an exotics-experienced vet promptly for: not eating, or eating noticeably less; fewer, smaller or absent droppings; laboured or noisy breathing, or discharge from nose or eyes; a hunched posture; dragging hind legs; crusty eyes; sudden weight loss; or any lump.

Weigh your guinea pigs weekly on a digital kitchen scale and write it down. Weight loss is the earliest reliable signal you will get, and it shows up before anything visible does.

Mistakes that shorten lives

Sources