Vitamin E Learning Hub

All horses need vitamin but a horse’s response to vitamin E supplementation depends partly on where that horse starts. A horse with adequate serum alpha-tocopherol may not need the same approach as a horse that is deficient, marginal, neurologic, growing, pregnant, lactating, confined, or in heavy work.

UC Davis recommends checking serum alpha-tocopherol concentrations and modifying dose or formulation if an adequate response does not occur. Their practical reference guidance lists greater than 2 micrograms per milliliter as adequate and less than 2 micrograms per milliliter as deficient.

Blood testing can provide valuable information about your horse's Vitamin E status. Testing may be particularly useful for horses with neuromuscular concerns, limited pasture access, or when determining appropriate supplementation levels. Discuss testing with your veterinarian to determine if it's appropriate for your situation.

Natural Vitamin E (d-alpha-tocopherol) is derived from plant sources and has a different molecular structure than synthetic Vitamin E (dl-alpha-tocopherol). Research suggests that natural Vitamin E is more bioavailable and retained longer in equine tissues compared to synthetic forms.

Vitamin E requirements vary based on individual factors including diet, workload, health status, and pasture access. The NRC provides baseline recommendations, but individual needs may differ. Work with your veterinarian or equine nutritionist to determine appropriate levels for your horse.

Vitamin E is a fat-soluble vitamin, and while toxicity is rare in horses, it's important to follow recommended guidelines. Excessive supplementation is generally unnecessary and may not provide additional benefits. Always follow product recommendations and consult with your veterinarian.

Fresh, green pasture is an excellent source of natural Vitamin E. However, Vitamin E content varies based on grass species, growing conditions, and season. Vitamin E levels are highest in actively growing, green forage and decline as plants mature or during dormant seasons.

Vitamin E is sensitive to oxidation and degrades rapidly after forage is cut. Studies show that Vitamin E levels can decline by 50% or more within days of harvest and continue to decrease during storage. This is why horses consuming primarily hay often benefit from Vitamin E supplementation.

Water-dispersible forms may offer advantages in specific situations, particularly for horses with fat malabsorption issues. However, for horses with normal digestive function, natural Vitamin E in powder or other forms is typically well-absorbed. The best choice depends on individual circumstances and should be discussed with your veterinarian.