Most health problems encountered in guinea pigs occur as a result of an inappropriate diet. In fact, it is possible to prevent many chronic problems by simply following some basic ground rules on guinea pig nutrition.
Guinea pigs need a high- fibre diet. Fibre is essential for maintaining a balanced bacterial flora in the gut and for stimulation of gastrointestinal motility. It is also crucial to the normal grinding motion needed to preserve the ideal length of teeth.
Hay should be the main source of fibre. It should be offered ad libitum and available at all times. Hay can come from many types of plants, which do not all offer the same nutritional value. Grass hay such as Timothy or Brome is ideal. Hay derived from legumes such as alfalfa is often sold in pet stores and is almost indistinguishable from grass hay. However, legume hay is higher in protein and calcium than grass hay, and although these nutrients are important for growing or lactating guinea pigs, they can be detrimental in adults in whom they can promote weight gain and urinary problems.
Leafy green vegetables are another excellent source of fibre, and offer other nutrients not found in hay. They should be provided fresh daily, at a minimum of a cup per day. It is important to diversify vegetables as they do not all carry the same nutrients, and some may even lead to imbalances if offered in large quantities (kale is high in calcium, for example). Lettuces, parsley, dill, cilantro, basil, mint, watercress, dandelion leaves, celery leaves, beet greens, chicory, escarole, rocket, kale, Brussels sprouts, collards and carrot greens are well appreciated by guinea pigs. High-sugar vegetables such as carrots or peppers can be offered in more limited quantities. High-sugar foods in general, and particularly fruit, can destabilize the delicate balance of bacterial populations in the guinea pig’s gut; they should therefore only be offered as occasional treats.
Several commercial diets for guinea pigs are available in pet stores. Choose pellets that are plain and do not contain added grains or dried foods; guinea pigs tend to select these instead of pellets. Pellets are essentially made from plain hay, and, like hay, it is recommended to choose a pellet that is made from grass hay. Although pellets are composed of hay, it is finely chopped and so does not confer all the benefits of untreated hay. In fact, when pellets are offered freely guinea pigs become more susceptible to weight gain, dental disease and digestive problems. Therefore, we recommend limiting your guinea pig's pellet consumption to 1/4 cup per day.
Guinea pigs also require a dietary source of vitamin C. Many pellets have added vitamin C, but it is a good idea to offer a supplemental source. Many leafy green vegetables are high in vitamin C, such as kale, collards and Brussels sprouts. Peppers, kiwis, strawberries and mangoes can also be offered in limited quantities in order to ensure adequate vitamin C intake. Vitamin C can also be provided in the form of tablets or powders. These are usually not necessary when the diet is very varied and balanced.
Guinea pigs are very sensitive to diet changes and an abrupt diet change can result in serious health problems. All diet changes should be instituted gradually and under surveillance. Some guinea pigs may refuse to eat hay because of underlying health problems (hay can be difficult to chew for a guinea pig with dental disease, for example). Consult your veterinarian to establish a diet plan that is adapted to your guinea pig.
Julie Hébert, DVM, Dipl ABVP (avian practice)