Guinea pigs have one dietary need that sets them apart from most other small pets: like humans, they can’t produce their own vitamin C and need to get it from their diet every day. Everything else follows a familiar small-pet pattern — mostly hay, a measured guinea-pig-specific pellet, and fresh vegetables.
Vitamin C matters — and the pellet has to be right
Because guinea pigs can’t make their own vitamin C, it’s worth double-checking that whatever pellet you’re feeding was actually formulated for guinea pigs, not a generic “small animal” or rabbit pellet — rabbit pellets don’t include the vitamin C guinea pigs specifically need, and a pellet that’s been sitting open for months also loses vitamin C potency over time, so freshness matters more here than it might for other small pets.
Hay, still the foundation
Just like rabbits, guinea pigs need unlimited fresh grass hay available at all times — it supports digestion and keeps their teeth, which also grow continuously, worn down properly. Timothy or orchard hay are the everyday staples for an adult guinea pig.
Fresh vegetables, and vitamin-C-rich treats
A daily portion of fresh vegetables — bell pepper is a particularly good vitamin C source — alongside the pellet helps top up their vitamin C intake. As with rabbits, introduce new vegetables gradually rather than all at once, and keep sugary fruit treats occasional rather than a daily habit.
Common feeding mistakes
The two we see most often: using a rabbit or generic pellet instead of one made for guinea pigs, and letting a bag of pellets sit open for so long that its vitamin C content has quietly dropped off. Buying smaller bags more often, and storing them in a cool, sealed container, helps.
Every pet is different — if your rabbit, guinea pig or chinchilla has a specific health condition, is a picky eater, or you’re changing their diet, it’s worth checking with an exotic-animal-savvy vet for guidance tailored to them.
Shop the essentials
Browse our guinea pig food, hay and vitamin-C treats — including Timothy and orchard hay — with fast islandwide delivery, or check whether it’s in stock at one of our pet vending machines near you.