Someone Surrendered Guinea Pigs to You — Here's the Intake That Keeps Them Alive

It usually shows up in a cramped pet-store cage with a bag of colorful muesli, a water bottle full of green algae, and a story about a kid who lost interest. Sometimes it's one lonely pig. Sometimes it's "a couple" that turns out to be a boar and a sow who've been sharing a cage for two months — which means you may have just taken in a litter you can't see yet. Guinea pigs look like the easiest intake you'll ever do: no vaccines like a ferret, no quarantine drama like a parvo dog, just a fuzzy potato that eats hay. That impression is exactly how they die on you. They hide illness as hard as a prey animal can, they crash from a vitamin deficiency most people have never heard of, and the mites they carry can kill them before you notice they're itchy. Here's the intake that keeps a surrendered cavy alive.

First, Separate and Sex Them

Before anything else, figure out how many animals you actually have and what sex they are — because if there's an intact boar and a sow in the same cage, the clock is already running.

Guinea pigs hit puberty fast: females can conceive at around two months old, males a little after.¹ A sow can be pregnant well before her owner thought she was old enough, and nobody surrendering "two girls" has usually checked. Separate any possible mixed-sex pair immediately and sex each animal carefully. Mature boars have obvious scrotal pouches and large testes; gently pressing just above the genital opening on a boar will express the penis, while a sow's opening forms a Y-shape.¹ If you're not sure, get a vet or an experienced cavy person to confirm — misjudging this is how a rescue ends up with an unplanned litter.

Assume any sow who was housed with a male is pregnant until proven otherwise, and treat her as the highest-priority animal in the intake. Which brings us to the reason that matters so much.

Why an Accidental Pregnancy Is a Genuine Emergency

Guinea pig pregnancy is not like a cat's. The two halves of a sow's pelvis are joined by a cartilage bridge, the pubic symphysis, that normally separates in late pregnancy to let the unusually large, well-developed pups pass through. But if a sow has never given birth before she reaches roughly six to eight months of age, that cartilage calcifies and fuses permanently, narrowing the birth canal so much that natural delivery becomes difficult or impossible.² A first-time mother bred after that window is a strong candidate for dystocia — an obstructed birth that, without an emergency C-section, kills the sow and the litter.²

On top of that, late pregnancy carries the risk of pregnancy toxemia, a metabolic collapse most common in overweight sows in the last two weeks before birth, with signs that run from loss of appetite and weakness to incoordination, difficulty breathing, coma, and death.³ The practical upshot: if you suspect a pregnant sow, especially one you think is bred late or is overweight, get her in front of an exotics vet early and know where the nearest emergency C-section is before you need it. This is the single fact that turns "easy small-animal intake" into a case that needs a plan.

They Cannot Make Their Own Vitamin C

Here is the deficiency that kills guinea pigs whose owners did everything else right. Guinea pigs, like humans, cannot synthesize vitamin C — they have to get it from their diet every single day, and a cavy on a low-C diet develops scurvy.⁴ The signs are easy to miss until they aren't: a rough coat, reluctance to move, swollen or painful joints, poor wound healing, diarrhea, and weight loss.⁴

A healthy adult needs roughly 10 mg of vitamin C per kilogram of body weight daily, which works out to about 20–25 mg a day for most adults and 30–40 mg for a growing or pregnant pig.⁵ The reliable way to deliver it is fresh: a daily handful of C-rich vegetables like bell pepper, plus a good timothy-based guinea pig pellet that's fortified with a stabilized form of the vitamin. Don't rely on vitamin C drops in the water bottle — the vitamin degrades quickly in light and water, and pigs often drink less when the water tastes odd.⁵ A surrender that arrived on a seed-and-corn muesli mix has almost certainly been running a C deficit, so building a proper diet is part of the intake, not an afterthought.

Feed Them Like the Hay-Burners They Are

The rest of the diet is simpler than the vitamin C question but just as important. The foundation is unlimited grass hay — timothy or orchard grass — available around the clock. Hay does double duty: it's the bulk of their nutrition and it grinds down their continuously growing teeth. On top of that, offer a measured amount of plain, timothy-based pellets (no seeds, no dried fruit, no colored bits) and that daily serving of fresh leafy greens and vegetables.⁶

Take whatever the pig came in with and, in most cases, plan to phase it out. The colorful muesli-style mixes let animals pick out the sugary bits and leave the rest, and they're a poor fit for a hay-first eater. Get them onto hay, plain pellets, and greens, and watch that they're actually eating the hay — a pig that stops chewing hay is often telling you its teeth hurt.

Quarantine, Then Look for the Usual Suspects

A surrender comes with no health history you can trust, so a new guinea pig doesn't meet your existing pigs on day one. Set it up in a separate space with separate handling and use the quarantine window as your observation period. As you settle it in, examine for the conditions that dominate guinea pig rescue.⁷

Skin mites. Trixacarus caviae is a burrowing mange mite that lives inside the skin, and it causes itching so severe that affected pigs scratch themselves raw and can have seizures triggered by the pain — untreated cases can be fatal.⁸ Any pig that's frantically itchy, losing hair, or crusty along the back and flanks needs a vet and treatment (an anti-parasitic like ivermectin or a modern isoxazoline), and its cagemates almost certainly need treating too. Don't write off intense scratching as "just dry skin."

Respiratory infection. Upper respiratory infections are one of the most common problems in the species, driven by organisms like Bordetella and Streptococcus.⁷ Watch for sneezing, nasal or eye discharge, crackly breathing, or a pig that's hunched and eating less. Respiratory disease moves fast in a small animal; it warrants a prompt vet visit, not a wait-and-see.

Dental disease. Because their teeth never stop growing, malocclusion is a recurring problem.⁷ The tells are drooling, a wet chin, dropping food, weight loss, or a pig that wants to eat but backs off the hay. This needs a vet with the equipment to examine and file the back teeth.

Bumblefoot. Pododermatitis — swollen, scabbed, ulcerated footpads — develops on wire flooring and in dirty caging.⁷ Check the soles at intake, and house pigs on solid floors with clean, soft bedding.

Ovarian cysts. In intact sows over about two years old, ovarian cysts are extremely common — one dataset found them in more than 75% of older intact females.⁷ The classic sign is symmetrical, non-itchy hair loss along both flanks, which is easy to confuse with mites until you notice the skin underneath is calm and unscaling. It's a reason to consider spaying and a good thing to flag to any future adopter.

They're Social — Plan for Pairs, Not Singles

One last thing that shapes the whole intake: guinea pigs are herd animals. In the wild they live in groups, and a lone pig is a stressed pig. The RSPCA advises keeping every guinea pig with at least one other friendly guinea pig unless a vet or behaviorist says otherwise, and Switzerland went so far as to make it illegal to keep a single guinea pig at all, treating solitary housing as a form of neglect.⁹ A stable group is often two or three sows with a neutered boar.¹⁰

For a rescue, that means a solo surrender isn't really "done" until it's bonded with a companion — which is also why sexing and neutering matter so much up front. Pair pigs deliberately, after quarantine and health clearance, and introduce them on neutral ground with plenty of hay and hiding spots.

Write It All Down

None of this works if it lives in your head. A surrendered guinea pig generates a lot of small, time-sensitive facts fast: sex and suspected pregnancy status, the date quarantine started, daily weight (a scale is your best early-warning system for a prey animal that hides illness), what it's actually eating, mite treatments and their repeat dates, vet findings. Keeping that in one place — whether a shared record in Pawsies or a dedicated intake sheet — is what makes the handoff to a foster or adopter clean, and what lets you catch the pig that's quietly eating less on day three instead of day eight. With an animal built to hide how it feels, the written record is the difference between a routine intake and an avoidable death.

This post is general guidance, not veterinary advice. A guinea pig with signs of illness, a suspected pregnancy, or a severe mite infestation needs an exotics-experienced veterinarian.