Feed Materials In Focus – Vitamin C



Vitamin C, or L ascorbic acid or ascorbate, is the horse’s most important water-soluble antioxidant. It’s quite a small compound and of course we perhaps best know it in human medicine for its role in curing scurvy in sailors. The symptoms of scurvy in people include feeling very tired and weak all the timesevere joint or leg painswollen, bleeding gums and teeth loss, development of red or blue spots on the skin, and skin that bruises easily. Scurvy in sailors at sea was caused by prolonged periods eating a diet with very few if any fruit or vegetables – humans cannot make Vitamin C themselves.  

Horses, like most animals including cats and dogs, can make Vitamin C themselves in the liver. Vitamin C has many different functions in the body including immunity, skin, tendon, ligament, cartilage, bone, teeth and blood vessel growth and health, wound healing, scar formation and iron absorption.  

Although horses make their own Vitamin C, there are many instances where horses can become Vitamin C deficient. For example, foals do not make sufficient Vitamin C until weaning and so they are initially entirely dependent on the mare for their Vitamin C. If the mare is deficient then the foal will be deficient. And as Vitamin C is crucial for skeletal development and respiratory health, this can have a serious impact on the foal. 

Horses with chronic conditions such as asthma and Cushings also often have low Vitamin C status. This can be assessed by measuring the concentration of Vitamin C in plasma from a blood sample, although Vitamin C is not easy to analyse. It’s very unstable and samples require rapid and specialised processing and analysis by specialised laboratories.  

Vitamin C supplementation in horses is very safe. However, horses do not absorb the natural form of Vitamin C found in fruit, vegetables, cereals or forages very well.  


About Author

Dr David Marlin is a physiologist and biochemist who has worked in academia, research and professional sport. He has worked in the equestrian and veterinary world and in human sport, healthcare, medicine and exercise science. In 1989 David obtained his PhD from the UK’s leading sports university, Loughborough University following a four-year study on the responses of Thoroughbred racehorses to exercise and training, undertaken at the renowned Animal Health Trust in Newmarket. You can read David's full biography in the Our Website section.