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Vitamin E in the equine diet

Vitamin E is an essential antioxidant that plays an important role in muscle, immune and neurological support in horses.

It is mainly supplied in the equine diet through green pasture. Horses are not very efficient at storing this fat-soluble vitamin and when access to green pasture is limited through management such as stabling, or due to environmental reasons such as hot and dry summers, the risk of vitamin E deficiency increases and supplementation is important to consider.

A deficiency of vitamin E may cause a variety of different symptoms and pathological changes, which may include poor immunity to diseases (recurrent cold and cough) and muscle stiffness, soreness or damage. If vitamin E levels in muscle tissue are inadequate in working horses, the risk of exercise induced muscle damage is increased.

Research in horses has mainly revolved around the role of vitamin E in maintaining normal function of the immune and reproductive systems, in optimising athletic performance and in studying diseases associated with vitamin E deficiencies.

One of the many highly qualified veterinarians and equine nutritionists that presented at the Kentucky Equine Research 30th anniversary conference in October 2018, was Stephanie Valberg, D.V.M., Ph.D., a professor at Michigan State University and director of its Neuromuscular Diagnostic Laboratory.

Dr Valberg provided information about the value of vitamin E as adjunct therapy for several neurological diseases, including equine neuroaxonal dystrophy/degenerative myeloencephalopathy (eNAD/EDM), equine motor neuron disease (EMND) and vitamin E deficient myopathy.

The goal of supplementation in horses susceptible to these diseases, according to Dr Valberg, is to increase the concentration of vitamin E in the central nervous system and muscle tissue.

“The impact of vitamin E deficiencies causing subtle but significant muscle atrophy and a decline in performance are under-recognised by many performance horse veterinarians,” Dr Valberg says. “It should be on everyone’s radar because it’s easy to diagnose with blood samples for vitamin E and can be readily treated with liquid vitamin E supplements.”

Vitamin E supplementation will vary according to the individual case and the amount of green pasture available to the horse, however Dr Valberg suggests a powdered, natural vitamin E supplement to maintain status in healthy horses. Horses suffering from EMND or vitamin E deficient myopathy should be supplemented with a natural liquid form at 5,000 IU/day until all clinical signs are gone, before transitioning to powder over a series of weeks once the horse returns to normal. Expect it to take several months for the horse’s signs to disappear.

Because horses’ responses to vitamin E supplementation vary, Dr Valberg urges veterinarians and/or nutritionists to measure vitamin E levels before and 4 weeks after supplementation and to adjust the dose accordingly.

NRM equine products all contain natural vitamin E formulated at the correct levels to meet requirements for horses in New Zealand, if fed according to directions.

For further assistance and advice on vitamin E supplementation, consult a qualified equine nutritionist.

Article supplied by Luisa Wood, Equine Nutritionist.