26/05/2026
🟢 Why Vitamin E Matters More Than You Think 🐴
Vitamin E deficiency is one of the most under-recognised nutritional problems we see in horses - particularly those living on restricted grazing or hay-based diets.
Vitamin E is far more than “just another vitamin”. It is a powerful antioxidant that helps protect cells from oxidative damage and plays a vital role in maintaining healthy muscle and nerve function. It is also important for the immune, reproductive and circulatory systems.
🌱 Where do horses get Vitamin E from?
Horses naturally obtain Vitamin E almost entirely from fresh green grass. The challenge is that once forage is cut and dried into hay or haylage, Vitamin E levels rapidly decline. By the time hay is fed, the amount remaining is often very low.
To complicate things further, many feeds contain synthetic Vitamin E, which is much less bioavailable than natural forms - meaning horses may not absorb or utilise it as effectively.
This means many horses on hay-based diets may not actually be meeting their Vitamin E requirements, even when the diet appears otherwise balanced.
Unlike some vitamins, Vitamin E is also not stored efficiently in the body, so horses need a consistent daily intake to maintain normal circulating levels.
❓ Can horses still be deficient even when turned out at pasture?
Yes - surprisingly, they can.
Not all pasture contains high Vitamin E levels, particularly during winter months, drought conditions, overgrazing or on poor-quality pasture.
Some horses may additionally have increased Vitamin E demands due to exercise, muscle disease or underlying illness. Others may struggle to absorb fat-soluble vitamins properly because of individual absorption issues, meaning they can remain deficient despite apparently adequate intake.
⚠️ What problems can Vitamin E deficiency cause?
Low Vitamin E can affect both muscles and the nervous system. Signs can vary from subtle performance issues to more severe neurological disease.
Possible signs include:
• Muscle soreness or stiffness
• Poor performance
• Weakness or muscle wasting
• Reluctance to work
• Weight loss despite adequate feeding
🩺 How can we test for it?
Vitamin E status can be assessed with a simple blood test. This allows us to measure circulating Vitamin E levels and determine whether supplementation may be needed.
Follow-up blood testing is often important after starting supplementation to ensure levels are improving appropriately.
💊 Not all Vitamin E supplements are equal
There are two main forms of Vitamin E found in equine supplements:
▪️ Synthetic Vitamin E
Less bioavailable and not utilised as efficiently by the horse.
▪️ Natural Vitamin E
Much more bioavailable and generally considered the preferred form when correcting deficiency.
There are also differences in formulation:
• Powder and pellet supplements are often esterified to improve shelf life, but require additional processing in the digestive tract before absorption.
• Liquid water-dispersible formulations are absorbed more rapidly and can increase blood Vitamin E levels within 24 hours, making them particularly useful when actively treating deficiency.
📏 How much do horses need?
Current recommendations suggest horses require approximately 1–2 IU/kg bodyweight daily for maintenance. Depending on the size of the horse or pony, this may range from around 250–1000 IU per day.
In horses with confirmed deficiency or clinical signs, much higher doses may be required - often around 5,000 – 8,000 IU/day - although requirements vary depending on the individual horse and any underlying disease.
🌿 What about long-term management?
Regular access to fresh pasture remains the best natural way to maintain adequate Vitamin E levels. However, this is not always possible - particularly for horses with EMS or those requiring restricted grazing.
Careful supplementation and monitoring can become an important part of maintaining muscle health, performance and overall wellbeing.
If your horse is on limited grazing, fed mainly hay, struggling with topline or muscle development/problems, or simply feels “not quite right”, Vitamin E deficiency is something worth discussing with your vet. 0808 168 5580