Vital Vitamin EJanuary 25, 2021
Sporthorse owners tend to leave no stone unturned when it comes to their mount’s health and well-being. Increasingly, the savvy equine manager must consider the importance of good nutrition in maintaining maximum performance levels and optimal health in her herd. Here in the Northeast, it is almost a certainty that one important vitamin will be lacking from any home-grown diet—vitamin E.
Vitamin E plays a critical role in both neurological and muscular health—and the harder a horse works, the more vitamin E he needs. The best source of this vital nutrient is high quality pasture; unfortunately, our northern climate, metabolic concerns, and limited grazing on most properties can all limit our horses’ access to this important resource. Although many commercial grain mixes sold in our region are supplemented with vitamin E, this nutrient tends to degrade quickly in stored feeds, even in the best quality products.
“The best source of natural vitamin E is stored in fresh green grass,” says Julie Vargas, DVM, CVA, CVMMP, head of the Sport Horse Medicine and Rehabilitation Divisions of Spy Coast Farm in Lexington, Ky., and veterinary advisor to Excel Supplements in Cincinnati, Ohio. “Even excellent quality hay begins to lose its nutritional value as soon as it is cut and stored.”
But vitamin E deficiency is prevalent enough in the Northeast that it should be a concern for all horse owners, not just those with elite equine athletes.
“I recommend vitamin E testing even if your horse isn’t a performance horse,” says Amanda Steneck, DVM, CVA, associate veterinarian with Massachusetts Equine Clinic in Uxbridge, Mass. “I have had backyard horse owners complain that their horse can’t maintain muscle, or is losing weight, or even that they are tripping quite a lot. We check their vitamin E and they come back as quite deficient. It is such a common issue we see in our practice.”
What is Vitamin E, and what does it do?
Vitamin E is a fat-soluble vitamin made up of eight compounds, each with a different level of activity in the body (see side bar). Alpha-tocopherol is the most researched and biologically available of these compounds.
“It is because of [these compounds’] solubility that vitamin E must be delivered with a fat for it to be properly absorbed by the horse’s body,” says Vargas.
As with the other fat-soluble vitamins (A, D and K), any vitamin E ingested by the horse in excess of his body’s needs will be stored within his fat cells (unlike the water-soluble vitamins, for which excess is excreted in urine). Its most critical role within the body is as an antioxidant, neutralizing free radicals produced during the metabolic breakdown of certain nutrients, particularly fats. The harder the horse works (especially if a large percentage of his energy is coming from fat), the more quickly he goes through his store of vitamin E—and the more likely he will be to require supplementation.
“Vitamin E is a multi-tasking antioxidant,” says Vargas. “Its many roles include maintaining normal neuromuscular function, supporting reproductive, immune and eye health, and improving skin and coat condition.”
Symptoms of vitamin E deficiency range from subtle to dramatic. General symptoms include overall poor condition, reduced performance, and muscle wasting and/or reduced muscle development as compared to workload. In more severe cases, horses can show neurological symptoms such as tripping, stumbling, toe-dragging, hindquarter weakness, muscle fasciculations (twitching) or ataxia. Steneck believes that horses with a change in attitude or history of behavioral problems warrant testing as well.
“It’s actually to the point that I recommend vitamin E testing before we test for Lyme’s,” says Steneck. “We have had so many presentations of [deficiency]. We test, we supplement them, and then the issue gets better. Unfortunately, here in New England our soil is quite deficient, which makes our pasture grass and our hay deficient as well. Pasture grass has the highest levels of vitamin E, but we have some horses that are on an adequate amount and they’re still vitamin E deficient.”
Vitamin E Management
Vitamin E deficiency is so pervasive throughout the Northeast that Steneck recommends testing levels in most horses every six to 12 months, and more frequently if issues arise. The first test will provide a baseline, and if the horse is deemed deficient, subsequent tests reveal whether supplementation is working and at what point maintenance levels are attained. Cornell University’s Animal Health Diagnostic Center puts normal equine vitamin E blood concentrations at anywhere between 200 and 1,000 ug/dL.
While there is a limit to how much vitamin E a horse can safely store within his body, its toxicity level is the highest of all the fat-soluble vitamins and therefore supplementation is generally considered to be quite safe. Because the range is so wide, deficiency so common and toxicity so rare, Steneck prefers to keep horses’ vitamin E levels on the higher end of the range.
“Vitamin E toxicity is not as much of a concern as it is with the other fat solubles,” says Steneck. “I would rather they be closer to 1,000 than 200, and I supplement any horse with a value of less than 400. I really like my performance horses to be closer to 500. That is my personal preference rather than from actual studies, but I feel they do better at a higher number.”
When it comes to vitamin E supplementation, all products are not created equal. Some provide vitamin E in a synthetic (laboratory made) form, which is not considered to be as readily absorbed by the body as vitamin E derived from natural sources.
“There are many forms of vitamin E, yet the naturally occurring form has been proven to be the most bioavailable when consumed,” says Vargas. “When choosing a vitamin E supplement, it is essential to read the ingredient list. For the most bioavailable form of vitamin E, look for the ingredient d-alpha-tocopherol.”
For deficient horses, Steneck starts off with a liquid vitamin E supplement, as it is readily absorbed and boosts levels quickly. After about a month, the horse’s vitamin E level is rechecked and if sufficiently raised, Steneck recommends slowly transitioning from the liquid supplement to a powdered version–which is easier on the owner’s pocketbook.
“Once they have solely been on powder for a month, then I’ll check it again to make sure they are holding their level okay just on powder,” says Steneck.
Vitamin E is an important nutrient when it comes to maintaining both overall health and top equine performance levels. Deficient soils in the Northeast, combined with limited grazing, mean that the forage our horses consume does not provide them with enough of this critical nutrient.
“Vitamin E is very important for both neurological and muscular health,” says Steneck. “I feel that almost every horse that lives in New England should be supplemented.”
By Christina Keim