Guinea pigs, like rabbits, are true herbivores, although the physiology and function of their gastrointestinal system is less well understood than that of the rabbit, which has been well investigated. Guinea pigs develop food preferences early in life and do not take to changes in food types, appearances or presentation very well. Sudden changes can result in a refusal to eat. Therefore, any modifications to the diet should be made gradually. The most critical aspect of the diet of guinea pigs is their requirement for vitamin C. Apart from that, the key to a healthy diet in a guinea pig is variety. The wild guinea pig in its native habitat of the South American forests ate a variety of foods, everything from fruits to leaves and plants to root vegetables. Pet guinea pigs are often fed a dry guinea pig mix with the occasional bit of fresh vegetables, which is an inadequate diet.
The preferred basic diet for guinea pigs is a commercial, high fiber guinea pig pellet with added vitamin C, offered free choice throughout the day. Some believe the sedentary adult guinea pig should have limited access to pellets. Guinea pig pellets should contain 18 – 20% crude protein and 14 – 16% fiber. Grass hay (such as Timothy hay) should be freely available. The diet should be supplemented with a variety of fresh, well washed leafy greens or colored vegetables (especially those high in vitamin C) such as red or green peppers, tomato, spinach, and asparagus. Other good choices for vegetables include broccoli, cauliflower, endive, kale, carrot tops, beet greens, cilantro, carrots etc. Iceberg or head lettuce has little nutritional value. Fruits should be limited as feeding too much of their high sugar content may lead to intestinal imbalances, and may cause serious and potentially life threatening diarrhea. Some preferred fruits to offer occasionally include those high in vitamin C such as orange (citrus) and kiwi. Oats, seeds, nuts and dry cereals should be avoided.
Fresh, clean water should be freely available. Sipper bottles must be cleaned daily and their tubes should be checked for obstructions in the tips. Water bowls are often not practical as guinea pigs are such messy house keepers. Food bowls should be heavy enough such that they are hard to tip over.
For every animal, there is a set of essential nutrients and non-essential nutrients. Animals need a regular dietary supply of essential ingredients, while they can produce their own supply of the non-essential nutrients. These essential elements differ between species. In the guinea pig and primates, including man, one key essential nutrient is vitamin C. The vast majority of other animals can produce their own vitamin C from their intestinal bacterial flora, but guinea pigs and primates are unable to do this. (This is why sailors historically developed scurvy when not able to eat fresh fruit.) 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 the healing of wounds. As well as predisposing to skin problems, a lack of vitamin C seems to make the body more prone to other diseases, infections and conditions. A guinea pig that has a rough hair coat, is off food, has diarrhea, is reluctant to walk, perhaps appears to be painful, has swollen feet or joints, or has hemorrhages and ulcers on its gums or skin is likely to be deficient in vitamin C.
Guinea pigs need between 10* – 50 mg vitamin C per day, depending on the condition of the animal (young, old, stressed, normal, pregnant). Vitamin C is readily available from fresh fruit and green or colored vegetables, but it is a relatively unstable compound. Ensure your fresh guinea pig pellets contain added vitamin C; because this vitamin breaks down or oxidizes so fast, the pellets must be used up or replaced within 90 days of the date of manufacture. If your guinea pig develops a deficiency, it is much better to give a crushed vitamin C tablet or liquid vitamin C by mouth rather than in drinking water, since the vitamin also breaks down rapidly in water and loses its potency. However, mixing about 100 mg of ascorbic acid twice daily in fresh water will meet the vitamin C requirement.
In summary, a variety of food items is extremely important to maintain your guinea pig’s health. Discuss your guinea pig’s diet with your veterinarian.
Rick Axelson, DVM
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