Importance of Vitamin E in Horses

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Holistic Horse copywrite

Vitamine E Archer Illustration

Free Radicals trying to attack the immune system

Vitamin E is the #1 antioxidant in the body, protecting individual cells every day. It is in every cell of your horse’s body and unique in being able to cross into spinal cord, brain, liver, eyes, heart, skin, and joints. In addition to being an antioxidant, Vitamin E is a “potent anti-inflammatory when given in high levels,” according to a University of Florida study.

Your horse does not make Vitamin E. Daily outside sources of Vitamin E are required to maintain the right blood and tissue levels to help protect cells. Nerve tissue especially requires Vitamin E to function properly. Horses quickly get deficient if they engage in moderate to high amounts of physical activity.

VITAMIN E IN GRASS

Fresh forage (grass) has a good amount of Vitamin E, but requires about 12 hours a day of grazing to get to the needed Vitamin E amounts. If your horse is on grass only a few hours a day, on a dirt lot, or has teeth issues and can’t graze correctly, they will be Vitamin E deficient.

Fresh grass changes throughout the year in its amount of Vitamin E. In October, the amount of Vitamin E in grass is very little. Levels in the winter (November-March) are at zero. Even on 12 hours of grazing April-September, horses will get only an estimated 1500-3000 units a day.

SUPPLEMENTATION IS NEEDED

Neurological conditions like EPM require large doses of Vitamin E due to high oxidative stress quickly depleting Vitamin E. The AAEP recommends 10,000 IU a day for several months; in our practice we will have horses go on 20,000 IU a day for 7-10 days and drop back to 10,000 a day in severe neurological/PSSM cases.

In older horses, Vitamin E supplementation has been proven to increase antibody levels which can protect them from sickness and help ward off infections from Cushing’s disease. In broodmares, it is shown that supplemented Vitamin E did pass through to milk and increase Vitamin E levels in foals, and also increased immunity cell levels from the mare to the foal. This can avoid many early-stage infections in foals.

How Much Vitamin E Does a Horse Need?

The amount depends on several factors. The more the horse is exercised, the more Vitamin E is needed due to more free radicals being produced; hence more Vitamin E is used up to protect cell membranes.

- To survive: 1000-2000 units (IU) a day

- Engaging in regular exercise: 5000 units a day

- Neurological problems like EPM, EDM, and EMND, PSSM: 10,000 units a day

- Broodmares: 5000 units a day

- Older (20+) or Cushing’s horses: 5000 units a day

Horses have no toxicity problem with Vitamin E even at very high levels, making it the safest vitamin to supplement.

IMPORTANCE OF ALPHA-TOCOPHEROL

Alpha-Tocopherol is the only form of Vitamin E with a transporting enzyme, allowing it to pass through the liver and, via blood, go to other cells. Other forms are broken down, eliminated in urine or manure or converted to Alpha-Tocopherol. In nature, the Alpha-Tocopherol portion is often only 10-15% of the total Vitamin E in the oil of the plant, but it’s the one that counts. Oils from Wheat Germ and Soy have large amounts of Alpha-Tocopherol but adding raw oil will not help your horse’s Vitamin E levels. Why? The Alpha-Tocopherol is very susceptible to heat, oxygen, and light – even fluorescent light will quickly destroy it. Just opening the bottle of oil would expose it to air and destroy most or all the Alpha-Tocopherol.

Alpha-Tocopherol is the only form stored for a small period in tissue, the only form metabolized by the liver, and the one with the most biological antioxidant action, so this is the form your horse needs. Supplements with lots of Gamma-, Delta-, or Beta-Tocopherol are not going to help. Pure plant oils may have good amounts of omegas but are poor Vitamin E sources.

BEWARE SELENIUM

Several products on the market with Vitamin E also contain selenium. To get sufficient levels of Vitamin E, and avoid selenium toxicity, you need an all-Vitamin E supplement with no selenium. Many areas of the US are selenium deficient and horses do need Vitamin E/Selenium combined products or selenium in grain mixes (Selenite). Generally, these products have very little Vitamin E and you will need to add an all-Vitamin E product. Vitamin E is absorbed better with a meal, so add it into the grain mix – most grain mixes have at least 5% fat which is good because a little fat in the diet helps Vitamin E absorption. (Lots of fat in cups of oil added to the diet will block Vitamin absorption.)

LABEL LANGUAGE

Equine and human Vitamin E supplements are semi-synthetic. Some will be labeled “natural” but even these required a chemical process to remove all other Tocopherols and leave only Alpha-Tocopherol. They are not pressed out oils from a plant and put in capsules or in a powder. Once this step is complete, the best supplements will do another step to preserve the Alpha-Tocopherol. Heat/light/air will destroy this Alpha-Tocopherol quickly, so if the supplement is not esterified (a second chemical step), your horse will not be getting the Vitamin E he needs.

On the label, you will see the words Alpha-Tocopherol Acetate, and this means stabilized (OK in heat, OK in air). You can put it in a tub on a 90°F day, 2 hours early, and it will be OK.  Look for a freshness date.

The easiest form to feed is a powdered supplement. Popping Vitamin E capsules is messy, often they are not freshness dated, may end up on the bucket sides and not in the horse, and cost more than concentrated Vitamin E.

If your horse needs 10,000 units and the product is 2000 units an ounce, it will take over a quarter pound of powder to get what is needed, due to it being packed in fillers and flavorings. You will go through a 2 pound tub in less than 10 days and that gets expensive. A Vitamin E supplement at 16,000 IU per ounce will require only 1 tablespoon per day to get over 5,000 IU and it is quick, easy, and economical.

Vitamin E is essential for your horse’s health. Most horses require a supplement source for optimal levels. The key is getting the most potent, stabilized, and correct form that is easy to administer.

Frank K. Reilly, DVM, is Senior Doctor at Equine Medical & Surgical Associates, Inc. in West Chester, PA. He has been in equine practice for 25 years and has worked on 6 world-record racehorses. He is a member of the AVMA, AAEP, and the newly formed AAPF professional farrier group. Dr. Reilly lectures at multiple events throughout the United States on equine Cushing’s, insulin problems, summer eczema and vitamin E deficiencies. www.equinemedsurg.com