Vitamin E for Horses: When Do They Need It

Last Updated on October 29, 2020 by Allison Price

group of horses standing on field

You may be asking if you can use Vitamin E as a supplement to the diet of your horse. Can your horse take advantage of it? Or, are green grass and sunshine enough? These may be some of the questions that you have when considering to add vitamin E to your horse’s diet.

Vitamin E serves as an antioxidant for horses. When your horse takes vitamin E, it boosts the immune system of your horse. Also, it helps support normal nerve as well as muscle function. 

They need vitamin E to synthesize the food they eat. You can usually find this in fresh and green grasses, also in forages. If your horse is usually on a rich pasture, he can have enough vitamin E when eating fresh grass. 

To know more about the importance and when your horse need vitamin E, keep scrolling!

Reasons Why Your Horse Need Vitamin E

Vitamin E is a term used to encompass the eight compounds. Namely, tocopherols or saturated and tocotrienols or unsaturated. These contain four structural variants. They the alpha, beta, gamma and delta. The most abundant and available in horse feeds is the Alpha-tocopherol.

Your horse needs vitamin E when he is going through oxidative stress. This can cause damage to the cells. Sometimes it can be so harsh to the point of cell death. It then causes organs and tissues to not function well like the liver and muscles. And it can have a negative impact on the health of your horse. Then, it can result to premature aging. 

Antioxidants, like the vitamin E, counteract the free radicals. Before causing damage to the health of your horse. 

Oxidative damage because of low antioxidant status or high free radicals… can be shown as muscle soreness after having an exercise. Or slow recovery from any illness. Or frequent illness. 

Feeding the right amount of vitamin E as well as other natural antioxidants… ensures that your horse has appropriate antioxidant defense. Especially if your horse is a high-performance one.

Benefits of Vitamin E for Horses

There are many benefits of vitamin E for horses. But the following are some of the top benefits:

1. Vitamin E helps ease muscle soreness and stiffness. Especially in exercising horses. It helps them sustain or keep high levels of activity.

2. With enough intake of this vitamin… the muscles of your horse can easily recover from exercise. This means it can support athletic performance.

3. Horses having enough vitamin E intake… have lesser tendency of experiencing chronic tying up.

4. This vitamin boosts the immune system of your horse. It helps kill the bacteria capacity of the immune cells. Vitamin E helps your horse recover from illness quickly.

5. Vitamin E helps horses with insulin resistance. Taking it 1000 IU per day can help improve insulin sensitivity.

6. Having enough antioxidant defenses can lessen stress and health issues. Especially if your horse is usually traveling or in competition. It helps your horse remain healthy and always ready for competition.

7. Vitamins E can help your horse if he is having muscular disorder.

The Green Grass So Full of Vitamin E

Good thing for horses because they have enough vitamin E provided in their diet from the nature. One of the great sources of vitamin E is the green grass. Most green things have a bit of vitamin E. If your horse is usually exposed to green grasses… he is lucky enough to get lots of vitamin E. With that, horses do not really need vitamin E on a daily basis. Because this vitamin can be stored well in the liver of your horses. They can last for many months during inadequate dietary intake. That is why horses that do not eat green grass during winter… don’t immediately start showing symptoms related to lack of this vitamin. Adult horses with previous enough dietary intake can live for 18 months… without taking vitamin E before they show symptoms of health problem.

four horses on grass field

Other horses are not privileged to always have access to green grass. These are horses staying in desert climates. But even in these areas, not all horses show signs of vitamin E deficiency. Vitamins E deficiency shows when the horse is older. Because that’s the time that deficiency develops. Sometimes it can also be genetic. 

If your horse does not have an access to pasture, watch this video:

Vitamin E Supplements

As horse owners, we must know the kind of vitamin E we are giving to our equine friends. There are two main types of vitamin E. They can either be natural or synthetic. There are cases that proves natural is better. The RRR form is the natural form of vitamin E. You will know if the vitamin E is a natural form by its name. It usually comes with a name of d-alpha-tocopheryl succinate, d-alpha-tocopherol or d-alpha-tocopheryl acetate. They usually have a prefix of “d” to easily distinguish that it is natural. Why natural vitamin? Because the natural form of vitamin E can be used by the tissues of the horse right away.

Synthetic vitamins usually have a prefix “dl”. Like dl-alpha tocopheryl acetate. Studies show that this form of vitamin E is not absorbed well by the horse’s body. The ability of the horse’s tissues to use synthetic vitamin E is lesser compared to the natural form. If you ever consider to use synthetic form of vitamins, know the content first and ask help from an expert.

In using synthetic form of vitamin E for horses… take into consideration the following:

· When you supplement vitamin E for your horse… there is a tendency that he will not respond even if you give an appropriate amount of it.
· Horses that have vitamin E deficiency… do not usually respond to supplementation of vitamin E.
· Vitamin E has an injectable form but they may contain selenium. But it seems like this injectable form do not have enough bioavailable. It does not have an effect in the rise of vitamin E serum levels. 
· When you supplementing vitamin E, you must have a specific reason. And there must be serum tests to see if supplementing it is effective. 
· It is threatening to give your horse vitamin E greater than 4 μg/ml.
· Also, it is not necessary to give your horse extra vitamin E when their serum level is in normal state.

Symptoms of Vitamin E Deficiency

Symptoms of possible vitamin E deficiency are in horses.

The most known or common symptoms is muscle degeneration. It affects the skeletal as well as cardiac muscle. Also, tongue muscle can be affected. It usually happens or shows in horses that are nursing.

You will know the status of your horse’s E vitamin… by the measure of plasma or the level of serum alpha-tocopherol. The first sign that a horse has vitamin E deficiency is when he has low levels of alpha-tocopherol. That’s why it must not go below 4 μg/ml as well. If your horse has low serum levels for a long time already, it can lead to clinical deficiency symptoms. 

These symptoms of clinical deficiency… are usually found in horses with low or insufficient vitamin E intake. But subclinical vitamin E deficiencies are usually not recognized in horses. Impaired immune system and reproduction problems are not recognized as the symptoms… but can be because of other causes besides limited vitamin E supplementation.

Vitamin E is Beneficial in All Life Stages and Performance Levels

Foals and Mares

Providing vitamin E is beneficial to breeding horses. It is good to feed your mare high levels of vitamin E during late pregnancy as well as early lactation. It is to make sure that the level of vitamin E is enough in colostrum and milk.


· Mares with poor-quality colostrum… should take twice the normal amount of vitamin E for a month before and after foaling.

· Pregnant mares eating lower quality of hay… must take vitamin E supplement a month before and after foaling. 

Mares having vitamin E supplements… show an increasing passive transfer of antibodies to foals. This can enhance the immune system in a greater way.

Exercising Horses

Synthetic vitamin E supplements in a certain level… are important in maintaining blood and skeletal muscle concentrations. Especially in horses going through exercise conditioning. 

The Vitamin E Requirements for your Horses

According to the National Research Council (NRC 2007)… they recommended that the vitamin E intake for mature (500 kg) horses is 500 IU per day at rest. If the horses have a light work, 800 IU is what they need. Also, 1000 IU is necessary for heavy loads of work. According to other studies, more vitamin E is better. For average-size horses on diet or not on the pasture, 5000 IU per day should be supplemented to them. With a balanced diet and with high-quality hay or grass, this is achievable. The vitamin E of horses which is considered as normal is greater than 2 μg/ml.

Horses with health issues must take higher vitamin E level is recommended. Horses that have allergies must have 5000 IU per day. Also, those horses that have muscle problems can have 5000 IU per day. Furthermore, horses that have laminitis, metabolic syndrome, and insulin resistance… can receive the same intake. Horses that are recovering from stress, illness and surgery may have 1500 to 5000 IU per day. For horses that have severe low weight, they need to have 1500 to 2000 IU per day. 

Where can I find these vitamin E?

The most essential and natural source of vitamin E is a good-quality green grass pasture. Most horses have more access to green grass where they can get this vitamin. Yet, horses are not required to have it on a daily basis. This explains why horses do not show any problems about the lack of this vitamin… even if they don’t have the access for green grasses. For adult horses, they can endure 18 months without having this vitamin… before health problems manifest. Also, keep in mind that fresh pasture has a high sugar content which could lead to overweight. The consideration of magnesium level of the grasses in springtime is a must.

Horses Grazing

But there are horses that do not always have access to green grasses. But even in the areas with desert climates, most of the horses do not show any signs of deficiency. Even if the pasture lands are likely to be deficient in vitamin… low percentage of horses show signs of deficiency. Whether horses show vitamin deficiency related problems or not… some factors may affect their health. These could be age, genetics, the period of time the horse experiencing deficiency… and undetermined factors.

It’s quite difficult to know if a horse is vitamin E deficient or not. Since some of them show no signs at all. No one can automatically draw blood… check the levels of vitamin E, and to have assurance that the horses have no problem. With an expert, such as veterinarian, a proper diagnosis is possible. They can identify the vitamin E status which can relate to vitamin E deficiency. Also, they will do a biopsy test for muscle, as well as removing disease that have the same signs. 

Good-quality grasses is a magnificent source of vitamin E for horses in any form. A horse that is overly exposed to good pasture can consume higher Vitamin E than the rule of NRC. Unfortunately, vitamin E is not stable in heat, so the level may decrease over a period of time. With this, horses that are in poor pasture or those who can’t maintain on good pasture must have enough hay to eat. Also, there are horses experiencing shortage of hay… so they should receive another source of this vitamin. The vitamin E level of a good commercial feeds must meet the requirements of NRC… if it suits to the guidelines of the manufacturer. Apparently, the feeds’ components have an impact to horses. It will be better for a veterinarian to run a test to see if there is another source of supplement required. This is a better approach for horses that show signs of vitamin E deficiency… or have worsened neurologic conditions. 

Also, selenium is added to various vitamin E supplement in the market. A 50 kg mature horse at rest or has a light work needs to have 1 milligram per day. And may increase to 2.35 milligram if the work is heavy. But the horse may not suffer any effect if he will have two intakes of selenium. Where in fact, the NRC rule of horses to have selenium is still unknown.

Researchers suggest that the intake of selenium per kilogram is 0.1 milligram… for consuming dry matters will prevent deficiency. But 3 milligrams of selenium per day compared to 1… shows a greater foals equine influenza antibody. This only shows that to get high immune function, there is a need to have higher intake of selenium. Also, this will lead to avoidance of classical deficiency syndrome. Moreover, 0.5 milligram per kilogram of dry matter being consumed… is the estimated tolerance of horses in selenium. 

In the U.S, the food and drug Administration has a recommendation. The largest concentration of selenium… should not be more than 0.3 milligram per kilogram in dry matters. The guidelines for selenium intake vary. The more you feed your horses, the consumed number of selenium is rising. So, you need to calculate the amount for you to know how much selenium the body of your horse can handle. 

The assimilation may vary. So, you should test the selenium level of your horse. This is to know the corresponding selenium level you can give. With that, you can ask for a veterinarian’s help for any adjustments. 


Vitamin E protects the membranes of your horse’s body. It’s not a typical vitamin. Vitamin E deficiencies do not always show symptoms like other vitamin deficiencies. If you want to enhance the immunity of your horse… the more that you need to give him enough of this vitamin. Also, make natural vitamin E a priority because it is better than synthetic.

Allison Price
Allison Price

I’m Allison, born and raised in San Diego California, the earliest memory I have with horses was at my grandfather’s farm. I used to sit at the stable as a kid and hang out with my Papa while he was training the horses. When I was invited to watch a horse riding competition, I got so fascinated with riding!