Guinea pigs are unique among other small mammals in their dietary requirements, since they require Vitamin C. Like humans, they are missing an enzyme that is necessary for the body to make Vitamin C. Therefore, they require supplemental Vitamin C in their diet.
Although guinea pig pellets have added Vitamin C, storage or exposure to light can rapidly destory it. Timothy hay and other grasses are poor sources of vitamn C. Therefore, we should not rely on the pellets or hay to provide the guinea pig with its Vitamin C requirements. We need to feed vegetables and some fruits. Vitamin C levels of foods commonly fed to guinea pigs are shown below:
| Excellent | Very Good | Fair | Poor* |
|---|---|---|---|
| Kale | Green Peppers | Red Cabbage | Beet Greens |
| Parlsey | Kiwi | Peas | Collard Greens |
| Sweet red and yellow peppers | Strawberry | Cantaloupe | Bok Choi |
| Broccoli | Mustard Greens | Oranges | Asparagus |
| Guava | Cauliflower | Snap Peas | Lettuce |
| Carrots | |||
| Turnip Greens | |||
| Kohlrabi | |||
| Papaya | | |
*Low Vitamin C or High Oxalates in comparison to the Vitamin C.
In addition to fresh guinea pig pellets, timothy hay, and fresh fruits and vegetables, it is generally recommended to provide guinea pigs with a daily vitamin C supplement in case they are not receiving adequate amounts in their diet. Oral supplements in the form of flavored tablets for guinea pigs are available and are an excellent option. An adult guinea pig should receive 25 mg of Vitamin C daily (30-40 mg for a pregnant guinea pig). Use products for guinea pigs that only contain Vitamin C. Using a multiple vitamin product to provide sufficient Vitamin C may result in an overdose of the other vitamins. Vitamin C tablets may be fed directly or crushed and sprindled on moistened fruits or vegetables. Vitamin C liquids are also available that can be given directly (not in the water). There are vitamin C drops that can be added to the drinking water, but the vitamin C in the water breaks down rapidly and may change the taste of the water, resulting in the guinea pig not drinking sufficient amounts of water. These types of drops are not recommended.
Vitamin C Deficiency
Signs of a Vitamin C deficiency in guinea pigs can develop quite rapidly (within weeks) if they are being fed a deficient diet. These signs include:
Loss of appetite
Depression
Ruffled fur
Weight loss
Swollen and painful joints and ribs; lameness
Poor bone and teeth development and a painful mouth
Nasal discharge
Bleeding gums and hemorrhages under the skin and into the joints
Infections
If identified before the guinea pig becomes too ill, the Vitamin C deficiency can be corrected and the guinea pig will recover, although Vitamin C injections and force feeding may be necessary if the guinea pig has a decreased appetite. Vitamin C injections are often necessary for any ill guinea pig, since it will usually eat less and therefore not take in sufficient Vitamin C.