Vitamin C, also known as ascorbic acid, plays an important role in a wide variety of bodily functions, and is regarded as essential for healthy wellbeing in dogs. As an example, it’s involved in the production of collagen and elastin which can be found in skin, bones, muscles, and tendons. As young dogs grow, they are laying down new tissue all the time, and research has shown they may need higher levels of vitamin C than adults to help with this process1. Vitamin C is also an antioxidant, a chemical that helps to prevent or delay cell damage, and it’s thought to play a role in metabolism and supporting the immune system2,3.
Spotting vitamin C deficiency
Stress is thought to be the biggest factor in vitamin C depletion in dogs. This can come from, for example, emotional stress through moving house or stress through injury. The major signs you will see as a result are slower wound healing and perhaps an increased susceptibility to disease. However, there are few other symptoms worth keeping an eye out for as well. For instance, bad breath, joint pain, and muscle weakness are all thought to be related in some capacity to vitamin C deficiency. If you spot these signs in your dog, then visit your veterinarian to discover the underlying cause4.
Potential benefits of vitamin C supplementation
Vitamin C acts as an antioxidant so there are some general health benefits to adding a vitamin C supplement to your pet’s meal in times of stress or illness5. Indeed, there are some specific conditions where extra vitamin C may be particularly useful.
Laboratory studies, for example, have suggested that vitamin C can inhibit the multiplication of some viruses. This isn’t due to its antioxidant properties; the vitamin is converted to dehydroascorbic acid and it is this metabolite that appears to have the strongest effect against viruses6.
Additionally, Chinese scientists discovered that if vitamin C was added to water and given orally to dogs with severe burns, there was less tissue damage than if water alone had been given7. Vitamin C has also been shown to have a protective effect on tissues that have had their blood supply restricted and then restored, which can occur, for example, during surgeries such as organ transplants8. This suggests that vitamin C can play a role in recovery from severe illness, injury, or surgery.
There has also been some research into the use of vitamin C for the treatment of cancer. In combination with vitamin K, there is a suggestion that it may contribute to the killing of cancer cells9. In these circumstances, vitamin C is given by intravenous infusion rather than by mouth. However, it appears that this treatment only slows down cancer growth: it isn’t curative and doesn’t cause remission.
Administration of vitamin C to seriously ill or injured dogs, or those that are undergoing cancer treatment, is given in a hospital situation. For dog owners at home who would like to supplement their pet’s intake, it is possible to include this in their diets through fruits, vegetables, and offal. Alternatively, vitamin C can be given in tablet or powder form.
Risks associated with vitamin C supplementation
Vitamin C doesn’t accumulate in the body and if given in excess, it’s excreted in the urine. This means that there is very little risk of toxicity or overdose.
Healthy dogs often don’t need extra vitamin C in their diet because they produce adequate amounts of this vitamin themselves. However, there are times when a little extra can be helpful. If your dog is stressed or recuperating from illness or injury, speak to your vet about whether adding some vitamin C to their diet would be appropriate.
1Ogawa, E. (2008). Age-dependent changes in uptake and recycling of ascorbic acid in erythrocytes of Beagle dogs. J Comp Physiol B, 178(6), pp.699-704. 2Hall, J., Picton, R., Finneran, P., Bird, K., Skinner, M., Jewell, D. and Zicker, S. (2006). Dietary antioxidants and behavioral enrichment enhance neutrophil phagocytosis in geriatric Beagles. Veterinary Immunology and Immunopathology, 113(1-2), pp.224-233. 3Plumb, D. (2015). Plumb's Veterinary Drug Handbook: Desk, 8th Edition. John Wiley & Sons. 4"Benefits of Vitamin C to Your Dog | Whole Dog Journal." 2006. [Accessed 18 Jul. 2016]http://www.whole-dog-journal.com/issues/1_7/features/5309-1.html 5Merckvetmanual.com. (2016). THE MERCK VETERINARY MANUAL. [online] Available at: http://merckvetmanual.com [Accessed 15 Jul. 2016]. 6Koyama, (1998). Antiviral effects of ascorbic and dehydroascorbic acids in vitro. International Journal of Molecular Medicine, 22(4). 7Hu, S., Che, J., DU, Y. and Bao, C. (2009). Observation on the effect of vitamin C in alleviating peroxidative damage in gut of dogs during enteral fluid resuscitation of severe burn shock. [Article in Chinese]. Zhonghua Shao Shang Za Zhi., 25(6), pp.451-3. 8Lee, J., Kim, M., Park, C. and Kim, M. (2006). Influence of ascorbic acid on BUN, creatinine, resistive index in canine renal ischemia-reperfusion injury. J Vet Sci, 7(1), p.79. 9Verrax, J., Cadrobbi, J., Delvaux, M., Jamison, J., Gilloteaux, J., Summers, J., Taper, H. and Calderon, P. (2003). The Association of Vitamins C and K3 Kills Cancer Cells Mainly by Autoschizis, a Novel Form of Cell Death. Basis of Their Potential Use as Coadjuvants in Anticancer Therapy. ChemInform, 34(33).
Author info: Dr Audrey Harvey is a graduate of the University of Queensland, Australia, and has worked in small animal practices for 25 years. She is particularly interested in obesity management and the role of exercise in resolving behaviour problems in dogs.