Feeding Guinea Pigs

By Gregory Rich, DVM; Laurie Hess, DVM; Rick Axelson, DVM

Guinea pigs, like rabbits, are true herbivores, although the physiology and function of their gastrointestinal system is not as well understood as the rabbit. Guinea pigs develop food preferences early in life and do not easily adapt to changes in food types, appearances, or presentation. Sudden changes can result in a refusal to eat. Any modifications to your guinea pig’s diet should be made gradually.

The most critical aspect of the guinea pig’s diet is their requirement for vitamin C. Like primates, guinea pigs can develop scurvy, so they must have vitamin C in their pelleted foods and vegetables. Apart from that, the key to a healthy diet in a guinea pig is unlimited amounts of timothy or botanical hay.

Like primates, guinea pigs can develop scurvy, so they must have vitamin C in their pelleted foods and vegetables. 

The wild guinea pig, in its native habitat of the South American forests, eats a variety of foods. It eats everything from fruits, leaves and plants to root vegetables, but especially a lot of high-fiber grasses. Pet guinea pigs are often fed a dry guinea pig mix with the occasional fresh vegetable, which is inadequate in fiber and generally too high in carbohydrates. Hay is critical not only to help wear down their continuously growing teeth, but also to keep the bacteria in their intestinal tract healthy and functional.

What should I feed my guinea pig?

The preferred basic diet for guinea pigs is unlimited amounts of timothy or other low-calcium hay, supplemented with smaller amounts of commercial, high-fiber, timothy-based guinea pig pellets. Vitamin C should be given each day (see below). Hay should be offered free-choice throughout the day. Hay and pellets should be supplemented with a variety of fresh, well-washed, leafy greens or colored vegetables - especially those high in vitamin C, such as bell pepper, tomato, turnip, collard greens, and asparagus.

Other good choices for vegetables include green and red leaf lettuce, Romaine lettuce, broccoli, cauliflower, endive, carrot tops, beet greens, cilantro, carrot, and squash. Do not offer iceberg or head lettuce as they have little nutritional value and contain mostly water.

Fruit should also be limited, as it has a high sugar content and feeding too much may lead to an imbalance of intestinal bacteria, which may cause serious and potentially life-threatening diarrhea. Some preferred fruits to offer occasionally include those high in vitamin C, such as small amounts of orange and kiwi, or high fiber fruits such as pear and apple. Oats, seeds, nuts, and dry cereals should never be fed to your guinea pig, as they are too high in carbohydrates and fat.

Fresh, clean water should be freely available. Clean sipper bottles daily, and check their tubes for obstructions in the tips. Water bowls are challenging, as guinea pigs often soil their water with food or feces or knock bowls over. Food bowls should be heavy enough that they are hard to tip over. Heavy ceramic bowls are usually safe to use for water and food.

Why do I need to give my guinea pig vitamin C?

Guinea pigs and primates, including humans, cannot manufacture their own vitamin C, so it is essential to supplement their diet with it. Vitamin C is vital for the normal development and maintenance of skin, joints, and mucosal surfaces, like gums. It also plays an important role in healing wounds. A chronic lack of vitamin C predisposes a guinea pig to scurvy, which will be evidenced by swollen joints, poor mobility and/or skin infections.

Low levels of vitamin C in the diet makes the body more prone to diseases, infections and skin problems. A guinea pig that is deficient in vitamin C has a rough hair coat, is off food, has diarrhea, is reluctant to move around, might appear to be in pain, has swollen feet or joints, and might have hemorrhages and ulcers on its gums or skin. Guinea pigs with these signs should be seen by your veterinarian as soon as possible.

"Low levels of vitamin C in the diet makes the body more prone to diseases, infections and skin problems."

Guinea pigs need 10-50 mg of vitamin C per day, depending on the condition of the animal (young, old, stressed, healthy, pregnant). Your veterinarian can tell you exactly how much vitamin C your guinea pig requires. While vitamin C is readily available from fresh fruit and green or colored vegetables, guinea pigs cannot consume enough produce every day to get the vitamin C they need. All guinea pigs should receive a vitamin C tablet or liquid vitamin C directly by mouth every day, rather than in their drinking water, since the vitamin breaks down rapidly in water and quickly loses its potency.

Also, while guinea pig pellets contain vitamin C, it is a relatively unstable compound that breaks down or oxidizes quickly. Therefore, be sure that your guinea pig pellets are used up or replaced within 90 days of the date of manufacture, or the vitamin C in the pellets may no longer be at an adequate level.

In summary, an unlimited quantity of hay, a smaller amount of vitamin C-fortified pellets, plus a variety of fresh produce is extremely important to maintain your guinea pig's health. Have your guinea pig checked annually by your veterinarian with whom you can discuss your guinea pig's specific dietary needs.

Related Articles