Do horses need it?
Vitamin B12 made in the gut is probably adequate if the diet has enough cobalt [1]. Adult horses fed a B12-free ration for 11 months showed no effect on blood values or health [1].
Injections
Injected B12 is largely excreted in the bile and is not recommended [1].
B vitamins in general
Studies since the mid-20th century have shown that thiamine, riboflavin, niacin, pantothenic acid, pyridoxine, folic acid, biotin and cobalamin are made in the horse's colon. Apart from experiments with deliberately deficient diets, clinical B-vitamin deficiency has never been reported in horses [2].
Claims that B-vitamin supplements improve hindgut function or help with coat changes have not been tested in studies, so they can't be validated [2].
See also cobalt.
Sources
- 1. Liburt NR (peer reviewed by Boyle AG). Nutritional Requirements of Horses and Other Equids. MSD Veterinary Manual, Professional Version. Merck & Co., Inc., Rahway, NJ. Last full review February 2026. https://www.msdvetmanual.com/management-and-nutrition/nutrition-horses/nutritional-requirements-of-horses (accessed 2026-11-07)
- 2. Henry Bergman S. Hästens behov av B-vitaminer (The requirement of vitamin B in horses). Bachelor thesis no. 616, Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences (SLU), Uppsala, 2017. English abstract. https://stud.epsilon.slu.se/13096/1/henry-bergman_s_180123.pdf (accessed 2026-11-07)
Last edited 7 Nov 2026, 1:48 am