25/03/2025
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🌱 𝐕𝐢𝐭𝐚𝐦𝐢𝐧 𝐄 𝐚𝐧𝐝 𝐇𝐨𝐫𝐬𝐞𝐬 🐴
Vitamin E is an important antioxidant that works to maintain healthy muscles and nerves. While vitamin E is plentiful in fresh forage, it quickly becomes depleted when forage is cut and preserved as hay. As a result, horses lacking access to at least six hours of quality pasture a day (often due to dry lot confinement or seasonal changes) may become deficient in this critical vitamin.
🔬 𝐖𝐡𝐚𝐭 𝐭𝐡𝐞 𝐫𝐞𝐬𝐞𝐚𝐫𝐜𝐡 𝐬𝐚𝐲𝐬
Previous research has found between 13 and 20% of horses are deficient in vitamin E (Muirhead et al., 2010; Pitel et al., 2020). However, when we tested horses at the local University who received hay and a free choice vitamin and mineral mix, up to 74% of horses were deficient in vitamin E. While grazing in the summer helped increase average plasma vitamin E concentrations, 59% of horses were still deficient after grazing for 3.5 months (hoping to publish this data soon if I can find time to write!). This data emphasizes the importance of evaluating vitamin E in the horse’s diet and verifying the efficacy through blood testing.
🔴 𝐃𝐞𝐟𝐢𝐜𝐢𝐞𝐧𝐜𝐢𝐞𝐬
While not all deficient horses demonstrate clinical signs of the deficiency, weight loss, muscle atrophy and weakness, as well as increased lying down, may be observed. More severe cases may result in neurological impairment. Thankfully, we continue to learn more about this deficiency which allows us to prevent and manage it more effectively.
🌱 𝐅𝐞𝐞𝐝𝐢𝐧𝐠 𝐭𝐨 𝐌𝐞𝐞𝐭 𝐑𝐞𝐪𝐮𝐢𝐫𝐞𝐦𝐞𝐧𝐭𝐬
When I balance a ration, I like to ensure horses receive the recommended levels of vitamin E in their feed – I consider any additional vitamin E provided in forage as an added benefit. This is because our management practices, including dry lot confinement and poor pasture management, often necessitate the addition of vitamin E in the diet, at least during part of the year. To do this, you can simply provide a fortified commercial feed based on the manufacturer’s recommendations. However, if you are feeding less than the recommendations on the feed tag, the horse will be lacking in critical vitamins and minerals, not just vitamin E.
However, it is important to note that horses may still be deficient even if they technically meet requirements according to the feed label. But why?
1️⃣ Well first off, horses can metabolize vitamin E differently. So while a horse may meet their requirements based on the label, they may remain deficient due to individual differences in how they utilize the nutrient.
2️⃣ Vitamin E is not very stable and can be compromised if not stored or handled properly. If this is the case, the horse may not actually receive what is promised on the label. While I am not worried about this when I am handling a product from a reputable company, it highlights the importance of using a tested product from a reputable brand and ensuring you store it according to their directions.
⚖️ 𝐒𝐨 𝐡𝐨𝐰 𝐝𝐨 𝐲𝐨𝐮 𝐤𝐧𝐨𝐰 𝐢𝐟 𝐲𝐨𝐮𝐫 𝐡𝐨𝐫𝐬𝐞 𝐢𝐬 𝐫𝐞𝐜𝐞𝐢𝐯𝐢𝐧𝐠 𝐚𝐝𝐞𝐪𝐮𝐚𝐭𝐞 𝐯𝐢𝐭𝐚𝐦𝐢𝐧 𝐄?
The most accurate way to determine if your horse is meeting requirements is through a blood test. I prefer to evaluate plasma or serum vitamin E moving into spring, before my horse has had access to fresh grass (you can have your vet pull blood when they are pulling a coggins). I find the spring to be one of the most beneficial times of year, as this is when horses are most likely to be deficient. However, a lot of horses will show a deficiency within a few months after they are removed from fresh grass. So if you test in the winter and catch a deficiency sooner, you can correct it quicker. Either winter or spring timing also allows you to determine if your feeding plan over the winter is effective. Once you receive the results, you can tailor your diet accordingly to meet requirements!
𝐖𝐡𝐞𝐧 𝐝𝐨 𝐲𝐨𝐮 𝐧𝐞𝐞𝐝 𝐭𝐨 𝐬𝐰𝐢𝐭𝐜𝐡 𝐭𝐡𝐢𝐧𝐠𝐬 𝐮𝐩?
If your horse is not deficient on the blood test, keep on doing what you are doing! At this point, more vitamin E has not been proven to be better and it is pretty expensive to feed! If your horse is deficient, you may want to consider switching feeds or adding in a supplement depending on the situation.
This nutrient is always on the forefront of my mind when balancing a diet and I am glad it is receiving the recognition it deserves.
✅ 𝐌𝐲 𝐦𝐚𝐢𝐧 𝐭𝐚𝐤𝐞𝐚𝐰𝐚𝐲𝐬 𝐚𝐫𝐞:
1️⃣ Make sure you feed a product based on their recommended feeding rate to meet requirements
2️⃣ Blood test to evaluate how your current feed program is working
3️⃣ Don’t just supplement blindly unless you enjoy spending money. Supplementing above requirements is only needed if your horse is deficient.
Cheers!
Dr. DeBoer
Muirhead, TL, Wichtel, JJ, Stryhn, H, McClure, JT. 2010. The selenium and vitamin E status of horses in Prince Edward Island. Can Vet J. 51(9):979-985.
Pitel, MO, EC McKenzie, JL Johns, and RL Stuart. 2020. Influence of specific management practices on blood selenium, vitamin E, and beta-carotene concentrations in horses and risk of nutritional deficiency. Journal of Veterinary Internal Medicine 34:2132-2141.
