The distinction between the animals is particularly significant when housing rabbits and guinea pigs together. Rabbit food is not supplemented with Vitamin C unlike the rations prepared for guinea pigs. A further complication arises because Vitamin C is a relatively unstable compound. It is, therefore preferable to buy small quantities of food regularly. This will ensure that the guinea pig receives a relatively fresh diet containing the optimum level of Vitamin C - about 200mg per kg of food (approximately 90mg per lb). Check the expiration date recommended by the manufacturer if you buy the food in packaged form. The maximum shelf life is likely to be no more than two or three months. Keeping the food in a cool, well-ventilated spot will help to prolong the vitamin content in prepared diets.

Apart from causing skin lesions, an early but unseen effect of Vitamin C deficiency is that it appears to render the body more susceptible to infections. Studies suggest that the average guinea pig weighing up to 1 kg (2.2lb) requires 10mg of Vitamin C daily, while during pregnancy this figure can increase threefold. If the guinea pig appears unsteady on its feet and reluctant to walk, with haemorrhages evident in the mouth and elsewhere on the body, it may have a Vitamin C deficiency. Direct dietary supplement of the vitamin -usually as part of a multivitamin powder but, in severe cases, in tablet form - tends to be more satisfactory than giving it in drinking water, where it rapidly oxidizes and loses its potency. To be beneficial, a solution would need to contain at least 200mg of Vitamin C per liter (114mg per pint) of water and should be changed once, possibly twice, daily. An added complication results if the water has been drawn through new copper pipes and so contains relatively high levels of this metal since copper acts as a catalyst for the breakdown of Vitamin C.

Ensure that the condition never arises, therefore, by providing fresh green leaf food throughout the year. Broccoli is particularly valuable because it has a very high level of Vitamin C, averaging around 250mg per kg (114mg per lb). Also provide root vegetables, notably swedes and to a lesser extent, carrots. These should be sufficient to keep your guinea pig healthy, especially when fed alongside a good-quality supplemented dry ration.