Complete pelleted guinea pig foods should be fed. Avoid mixtures as guinea pigs are selective feeders and thus may avoid some essential parts of the food, resulting in an unbalanced diet. Hay and grass must be available at all times to ensure adequate fibre in the diet. Fibre is essential for dental health. Guinea pigs must receive adequate supply of vitamin C in their diet as they are unable to synthesise it themselves. Vitamin C will be added to good quality guinea pig pellets but storage conditions and shelf life of the diet must be adhered to. Fresh water must be freely accessible.

Guinea pigs teeth grow continuously and they wear down during eating. The correct diet is vital to ensure adequate wear and prevent dental problems. Adequate fibre in the diet is essential to minimise dental problems.