A few months ago, we helped two horses who were suffering a great Vitamin E deficiency. Remember? Chatterbox and Blue.
Well… I got to thinking… I had a mastiff who passed from an elusive muscle disease when he was still a puppy. After the necropsy, it was determined that he had a Vitamin E deficiency. And, if we had determined that in time, we could have helped him.
Hmmmm.
Why wasn’t this on my vet’s radar? I figured it was rare or a fluke or… dunno.
But then when I heard about Chatterbox and Blue, I did research on Vitamin E deficiency – and I thought I’d pull you all in on what I discovered.
BRIEFLY, I WILL STATE WHAT I THINK after doing some reading (I have a great article in the next section.)
Here is what I have determined for my horses:
- Vitamin E is sourced through green grass. Most grass hay only has remnants of Vitamin E when it is fresh. The longer the hay sits, the less the Vitamin E.
- As a horse ages, Vitamin E helps with ‘older horse’ diseases like Cushings.
- Young horses who may have a genetic tendency to not absorb E well, benefit from supplementation.
- Often Vitamin E deficiency is misdiagnosed as a muscle wasting disease. And, muscle wasting disease protocol is often large doses of Vitamin E
- You cannot overdose your horse on Vitamin E
- HOWEVER, you can overdose your horse on Selenium… and Vitamin E and Selenium are often together. Your horse may need selenium, but the amount of Vitamin E with the selenium is not much of a benefit… so best to dose these two separately. Or to add E separately so as not to overload the selenium
- Read the label! For Vitamin E to be stabilized and actually work for your horse, it has to go through a few processes (which makes it more expensive). Look for the words, “Alpha-Tocopherol Acetate” which means it is stabilized.
- If your horse is already showing neurological signs of Vitamin E deficiency, you can help them but it is not curable or reversible at that point. So, dose them NOW, before you see signs.

This is what I purchased – and where for the best price today – upon the recommendation of Darla from Strawberry Mountain Mustangs who rescued and treated Chatterbox and Blue.
A GREAT ARTICLE
I found several articles on Vitamin E for horses, but I thought this short, succinct article written by DVM Frank K. Reilly for Holistic Horse was the easiest to understand.
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.
ADDENDUM!
A reader just emailed me and said that her vet told her to use Costco brand Vitamin E with the label “Alpha-Tocopherol Acetate” for her horse with muscle wasting. She said she sees a remarkable difference!
This bottle of 500 gel caps costs around $9.99. She puts 10 on his grain/supplement bucket and he eats them no problem!

Please cite your sources. Dr Valberg 2018 “Supplementing Horses With Vitamin E” (do Google search for that article) in both Vitamin E Deficient Myopathy and EMND can be reversed if caught and supplemented early, and it may take several months for symptoms to dissapear.