The Inside Scoop on Vitamin E

As equestrians, the well-being of our horses is at the forefront of our minds. A major component of horse health is a quality, balanced diet that meets their unique nutritional requirements. In addition to forage and concentrated grain products, many equestrians utilize supplements to ensure that their horse’s dietary needs are being met.

One vitamin supplement that continues to be in demand by our customers is vitamin E. Keep reading to understand the importance of this vitamin and the surprising effects of vitamin E deficiency.

Vitamin E Explained

Vitamin E is a fat-soluble vitamin that acts as an antioxidant and protects cell membranes by neutralizing free radicals, unstable cells which can cause damage within the body. It is responsible for ensuring healthy immune, cardiovascular, and reproductive function in the horse. This essential vitamin plays a very important role in maintaining the health of your horse’s neurons as well as muscles, helping your horse recover after strenuous exercise and to decrease muscular stress levels. Because of the role that vitamin E plays in the body, deficiencies often manifest as neuromuscular conditions and diseases, such as Vitamin E Deficient Myopathy, Equine Motor Neuron Disease (EMND), White Muscle Disease, Equine Neuroaxonal Dystrophy (NAD), and Equine Degenerative Myeloencephalopathy (EDM)

In theory, horses receive their vitamin E from the food sources, because it is naturally occurring in green grass in the pasture. However for many horses, especially horses based in the New England area who do not have access to green pasture, vitamin E deficiencies are commonplace. Christina Cassano, DVM, an intern veterinarian at New England Equine Medical and Surgical Center in Dover, NH, explains, “It is easy for horses to become deficient in this vitamin since our pastures are only lush and green for several months out of the year. Selenium is another antioxidant that works along with vitamin E and is commonly deficient as well.”

Conditions Associated with Vitamin E Deficiency

Vitamin E deficiency is a serious health concern in horses and should be quickly addressed. In the beginning stages of vitamin E deficiency, horses may present with stiff muscles, dry skin, and a dull hair coat. As the deficiency of this essential vitamin continues, the symptoms may include less muscling along the topline, swelling of the joints, loss of coordination, poor wound healing, and distinct brown pigmentation in the pupils of the eye. If you see these symptoms, it is necessary to test your horse for a deficiency before it develops into permanent damage.

In addition to the general health of your horse, there are a number of conditions and diseases that can manifest during long bouts of vitamin E deficiency:

Vitamin E Deficient Myopathy is a condition that results in muscle atrophy and weakness, especially along the top line of the horse. Clinical signs include muscle wasting, muscle weakness, muscle fasciculations (rapid contractions), and poor performance. To diagnose Vitamin E Deficient Myopathy, blood tests are run to determine the vitamin E level, which can sometimes be normal despite clinical signs. In these cases, muscle biopsies can be performed to look for evidence of vitamin E deficiency at a cellular level. Vitamin E supplementation is the primary treatment for this condition. 

Equine Motor Neuron Disease (EMND) is the result of chronic vitamin E deficiency and affects the motor neurons that provide nervous input to muscles. “Without motor nerve input, the muscles experience atrophy leading to generalized muscle wasting, muscle fasciculations, a short-strided gait, shifting of weight while standing, a base narrow stance, elevated tail head carriage, and lowered head and neck carriage,” explains Dr. Cassano. EMND is diagnosed through muscle biopsy and/or nerve biopsy, as well as assessing the vitamin E levels in blood serum. Treatment of EMND is high doses of vitamin E, but it should be noted that affected horses may not recover completely from this disease. 

Equine Neuroaxonal Dystrophy (NAD) and Equine Degenerative Myeloencephalopathy (EDM) are two very similar conditions that affect young horses by the time they are six to twelve months old. These extremely serious conditions are the result of damage to the neurons within the central nervous system. According to Dr. Cassano, “Clinical signs of NAD and EDM include mild to severe ataxia that affects all four limbs, but manifests more severely in the hind limbs.” Horses can display a base wide stance and have deficits in body awareness (proprioception). “Diagnosis in the live horse is made through ruling out other causes of neurologic disease and by determining blood levels of vitamin E, but unfortunately a definitive diagnosis can only be made postmortem by performing histopathology on brain and spinal cord samples,” she explains. Horses with these conditions will have lifelong neurologic deficits. Treatment with vitamin E supplementation will prevent further damage to the central nervous system but will not reverse the effects.

Nutritional Myodegeneration, also known as White Muscle Disease, is a result of vitamin E and selenium deficiency that begins in utero. Usually diagnosed when the foal is still young, this disease results in damage to skeletal and cardiac muscle. Clinical signs include muscle weakness, inability to stand, muscle trembling, and firm and painful muscles. In extreme cases, the heart will be affected and will result in a rapid heart rate, difficulty breathing, and potentially heart failure leading to sudden death. A diagnosis is made by measuring muscle enzymes and vitamin E and selenium levels in the blood. Treatment includes vitamin E and selenium administration, but in cases of cardiac involvement, treatment will usually be ineffective. 

Vitamin E Testing and Supplementation

It is a good idea to have your horse’s vitamin E and selenium levels tested periodically to determine if they might need supplementation, and especially if you notice muscle loss along the topline in active horses. Veterinarians conduct a blood test to determine the amount of vitamin E in your horse’s system. “When blood is tested for vitamin E levels, a value greater than two micrograms per milliliter is considered adequate, while a level below this value is considered deficient,” explains Dr. Cassano. 

If your horse is vitamin E deficient, supplementation of this essential vitamin is recommended. According to Dr. Cassano, “The upper end of the recommended daily requirement for vitamin E is 20 IU/kg of body weight. A one-thousand-pound horse needs about 10,000 IU per a day. Most horses receive vitamin E in their regular diet but can be supplemented with 1-2 IU/kg of body weight per a day to reach their daily requirement.”

Due to its role in muscle health, many performance horses need additional vitamin E to support their body processes. Even horses who are not deficient in vitamin E may benefit from low levels of supplementation to ensure they maintain adequate levels.

There are a number of vitamin E and multivitamin equine supplements to assist you in supporting the health of your horse. Vitamin E is supplemented as alpha-tocopherol, which is the most bioactive form in animals. We carry a number of quality vitamin E supplements for horses in both powder and pellet form, including Animed Vitamin E Powder Concentrate and Kentucky Performance Products Elevate Se (which also contains selenium). Learn more about the various types of supplements on our blog post, Demystifying Vitamin E Supplements.

Work with your veterinarian to determine the proper dosage. Frequent testing can reaffirm the dosing and allow you to adjust your administrations accordingly. vitamin E toxicity can occur, so over supplementing is not recommended. Extremely high levels may prevent other fat soluble vitamins from being properly absorbed.

This essential vitamin plays a large role in the health and wellness of your horse. Fortunately, it is also easy and economical to supplement. Due to the environmental factors, the vast majority of horses living in the Northeast (especially horses who are not on lush pasture) will benefit from the addition of vitamin E into their diets.

Does your horse exhibit the signs of vitamin E deficiency? Talk to one of our experienced sales associates to determine which supplement would work best for your horse. We encourage you to consult with your veterinarian if you have any questions regarding your horse’s health and wellness. The information provided in this blog is for informational purposes and is not meant to replace routine veterinary care.