I use vitamin C crystals that are added to one of my girl's water bottles every other day or so. I did have to do some math to be sure I was giving the correct amount and not too much, but they actually drink more water with a little vitamin C in it than otherwise. Just a thought.
I can't speak for vitamin C and malo, but I do know that I was working on some chinchilla nutritional research a few years ago and actually read the research that determined that vitamin C is not necessary in a chinchilla's diet. The researchers determined that vitamin C is not a vital nutrient, in that chinchillas do produce enough to survive on without supplementation in normal circumstances. However, they did not have any evidence that supplementation was in any way detrimental. The study was limited to determining if vitamin C was vital, which means that they had no evidence for or against situations where it might be useful to provide more than the animals create on their own. There are any number of circumstances documented in other vitamin-C producing animals where they are unable to meet their metabolic needs and require some level of supplementation, whether it is caused by illness, genetic disease, or some other mechanism.
I provide Vitamin C because Inca had a growth spur in one of her back molars because of insufficient diet during her pregnancy, and I'd like to do everything I can that might help prevent a recurrence. It has been 3 years since the spur, with no indications that it was anything other than a nutrition-based phenomenon. There is no research directly supporting vitamin C as an effective prevention or treatment of malo, but there is plenty of evidence that vitamin C is essential for dental health in many mammals. Unlike other vitamins that have a very high risk of toxicity (like vitamin A), vitamin C is water-soluble, does not collect in the body, and if given in proper doses is a safe vitamin to supplement. Therefore, I choose to supplement.
I've put some references I used in my research at the end of this post, so if you want to, you can find and read them. They are a very limited sampling, but they have some very good basic data.
Hope that helps!
Steph
King, K., Orcutt, F. 1952. Nutritional studies of the chinchilla with special reference to ascorbic acid and thiamine. J. Nutrition. 48: 31-39.
Larrivee, G., Elvehjem, C. 1954. Studies on the nutritional requirements of chinchillas. J. Nutrition. 52: 427-436.
Sakaguchi, E. 2003. Digestive strategies of small hindgut fermenters. J. Anim Sci. 74: 327-337.
Donnelly, T. 2004. Guinea pig and chinchilla care and husbandry. Vet Clin Exot Anim. 7: 351-373.
Wolf, P., Schroder, A., Wenger, A., Kamphues, J. 2003. The nutrition of the chinchilla as a companion animal – basic data, influences and dependences. J. Anim. Physiol. a. Anim. Nutr. 87: 129-133.
Leoschke, W., Elvehjem, C. 1959. Riboflavin in the nutrition of the chinchilla. J. Nutrition. 69: 214-216.
Crossley, D. 2001. Dental disease in chinchillas in the UK. J. Small Anim. Prac. 42: 12-19.