Oxidative Stress in Horses

What's the Story?

By Tom Schell, D.V.M.

The term “oxidative stress” has been bandied about in recent human research in relation to diseases ranging from allergies to cancer, but is there a connection to horses?

And, just what is oxidative stress?

Essentially, it’s an imbalance between antioxidant capabilities of the body and the level of free radicals being produced. Antioxidants are compounds consumed and produced by the body whose job is to neutralize free radicals. Examples of antioxidants in the average diet are vitamin E, vitamin C and selenium.

Free radicals are essentially toxic by-products of oxygen metabolism that are produced in the body as a result of normal breathing or respiration, diet, exercise and other physiological activities. They are also produced as part of the body’s natural defense mechanism in times of infection with bacteria and viruses.

Serving many purposes within the body, free radicals are generally associated with inflammation and quickly resolves once the activity is discontinued. They are damaging to tissue and can lead to altered fats and proteins, as well as cellular DNA, which can then lead to altered cellular function. Antioxidants are naturally produced within the body and are also consumed in the diet. Their main job is to neutralize and reduce free radical levels reducing cellular damage. Problems in the body begin to happen when one of two events occur: reduced antioxidant levels and/ or increased free radical levels.

Oxidative stress has been associated with many equine clinical conditions, such as recurrent airway obstruction (RAO), grass sickness, motor neuron disease, degenerative myelopathy, white muscle disease, post anesthetic myopathy, laminitis, degenerative joint disease and certain reproductive disorders. Exercise has also been shown to generate high levels of free radicals.

Timbercreek Veterinary Hospital in Jonesville, N.C. has been investigating oxidative stress in a variety of equine conditions presented by utilizing a specialized laboratory device called the FRAS-4, which evaluates d-ROM (reactive oxygen molecules), as well as BAP (biological antioxidant potential) level. The reactive oxygen molecules are related to the levels of free radicals, while the biological antioxidant potential is directly related to the level of antioxidants within the bloodstream.

The Timbercreek research shows a distinct pattern of elevated free radicals, as well as a deficiency of antioxidants in many disease conditions admitted for care. Based on Timbercreek’s research values, the average normal horse would demonstrate a healthy free radical level or d-ROM of 130-150 UCARR and a normal BAP level of >2200 uMol/L. In many instances of laminitis and other inflammatory conditions, the horses presented with d-ROM levels in excess of 250 UCARR and BAP levels averaging around 1700 uMol/L. This indicates that the inflammatory process occurring within the patient is generating an excess of free radicals and depleting the antioxidant stores creating an imbalance or oxidative stress.

So, the “big deal” is that free radicals are being generated as a result of many disease conditions affecting the horse. In order to potentially control many of these diseases, reduce clinical signs and help increase the exercise capabilities of the horse, free radicals must be controlled. This is an aspect of therapy that is not considered a top priority in many instances. The natural method of controlling free radicals is via antioxidants produced either naturally or consumed in the diet. A problem with today’s equine diet is that many grain products are processed, leading to lower nutrient levels. Hay products that are being produced from potentially depleted soils also contribute to lower overall nutrient levels.

Based on Timbercreek’s research, many horses with inflammatory conditions are presenting with decreased antioxidant levels, while being on normal perceived healthy diets on the farm. The results imply that supplementation with antioxidants is necessary to help boost levels and guard against potential disease.

The question is which antioxidants are needed and at what levels? Human research implies that supplementation with more than one antioxidant seems to provide better coverage than just one antioxidant, more likely due to synergism between compounds and different levels of action. So, which ones do we use?

In addition to evaluating oxidative stress in horses, Timbercreek has been evaluating the impact of an all natural anti-inflammatory compound which supplies natural antioxidants called Cur-OST®, which contains curcumin, green tea extract and other key ingredients.

Keep in mind that the use of traditional anti-inflammatory medications, such as phenylbutazone does very little to reduce free radicals in the equine body. These medications are generally utilized to help reduce inflammatory proteins such as COX-1 and COX-2, which then result in decreased levels of prostaglandins associated with pain and inflammation. The overall inflammatory process itself involves many players per se. One of them is inflammatory proteins such

as interleukins, matrix metalloproteinases and prostaglandins.

The other component is free radical production which can then trigger more inflammatory proteins to be produced. To control the overall inflammatory process, both the inflammatory proteins and the free radicals being produced, need to be controlled. Traditional therapies with non-steroidal anti-inflammatory such as phenylbutazone only tackle half of the problem

Oxidative stress clearly impacts the body in many different ways and can result in a multitude of problems ranging from orthopedic disease to exercise intolerance. Antioxidants are important means of protection against the effects of free radicals, which help to slow disease progression as well as improve physical performance.

Diet is very important in order to help supply antioxidants, but supplementation may be needed, especially for those horses at an increased risk. Free radicals as well as antioxidant levels can be monitored through specialized blood testing in order to ensure protection. Supplements, such as Cur-OST® have demonstrated the ability to reduce not only inflammatory proteins in the equine body, but also have the ability to decrease free radical levels and increase antioxidant capabilities, thus providing a good all around level of protection.

So, as you can see, an apple a day may just possibly keep the doctor away.

Timbercreek Veterinary Hospital Research Results

Joint fluid samples in a small population of arthritic horses were evaluated by Timbercreek Veterinary Hospital before and after supplementation with Cur-OST®, an all natural anti-inflammatory supplement created by Nouvelle Veterinary, Inc., which contains curcumin, green tea extract, vitamin C, vitamin E, Co-Enzyme Q10, mushroom derived beta-glucans and alfalfa herb powder. Vitamin C, E and CoQ10 serve primary purposes of providing antioxidant protection against free radicals.

The principal of the study was to evaluate for a reduction in inflammatory proteins PGE-2 and MMP-9. The study showed an average of up to a 50 percent reduction in PGE-2 and MMP-9 in synovial fluid after 30 days of supplementation, demonstrating the ability of the supplement to reduce inflammatory proteins in horses. This has been known to occur in humans based on prior research studies with the level of clinical lameness of horses also improved by at least one grade.

In another study performed at Timbercreek, insulin resistant horses with secondary laminitis were evaluated for free radical and antioxidant levels as well as overall response clinically to Cur-OST®. The study results indicated that the majority of the insulin resistant horses presented to the hospital demonstrated a level of oxidative stress with elevated free radicals and decreased antioxidant levels, which were improved after two weeks of supplementation. Insulin levels in six patients were also clearly reduced after two weeks as well as an improved lameness score. These results correlate well with a human research study that concluded that there was a connection between metabolic syndrome and oxidative stress.

Thomas Schell, D.V.M. is the founder of Nouvelle Veterinary. He is a graduate of The Ohio State University, as well as board certified by the American Board of Veterinary Practitioners in Equine Practice.

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