Commonly Used Nutritional Supplements
While calcium supplements are actually not often used (excess calcium may be linked to bladder stones), they are reportedly helpful for some animals experiencing unexplained difficulties moving the hind legs or with diagnosed bone loss. Calcium lactate is an easily digestible form of calcium and can be used at 25 mg/kg. Additional vitamin C is also advised. If it is possible your pet has been injured, see a vet for diagnosis and treatment.
Critical Care -- (dietary supplement)
Critical Care has received high praise from those who have used it. Available by mail order, the Oxbow Hay Company prefers that you contact your veterinarian (who should examine and diagnose your pet's illness) to order it. They provide a phone number for emergencies. For more information, read the article on Hand Feeding
Lactated Ringers Solution -- (fluids and electrolytes given subcutaneously, by prescription only)
Josephine has mentioned that there are different types of fluids for different conditions. The most common is LRS (Lactated Ringer's Solution) which is an RX only product.
Vitamin B 12
0.25ml of B12-- 0.25mg by subcutaneous or intramuscular injection. Can also be given orally.
Many vets will include C and B vitamins when administering subcutaneous fluids. VC Richardson feels this is a very useful vitamin for ill guinea pigs, especially if they are weak or not eating. Boars suffering from impaction may need supplementation with B vitamins (see Impaction).
Vitamin C (Ascorbic Acid) -- (Read about scurvy)
Oral Dosage: 50mg/kg to treat scurvy, 25 to 50mg/kg for ill pigs, 25mg/kg for healthy pigs
Chewable flavored C can be found in 100 mg tablets which when quartered will add 25 mg to a guinea pig's intake. Some people have good luck with liquid vitamin C, which can be found at some health food stores. In cases of deficiency, providing small amounts of vitamin C several times during the day when hand feeding or administering medications may help treat scurvy more quickly. A pig with scurvy will often show improvement within a week of treatment.