What Exactly is Equine Metabolic Syndrome (EMS)?

By Kim Hallin

The truth is, it’s easier to determine what EMS is not than it is to determine what EMS is, exactly.  For instance, EMS is not a disease in itself. Rather, the term is used to describe a condition (or set of conditions) characterized by symptoms which may include insulin resistance, hypothyroidism, and obesity.

Veterinary medicine speaks of a “syndrome” when it finds visible and consistent symptoms without knowing what causes these symptoms are based upon. The definition of EMS is continually changing and evolving as scientists and nutritionists learn more about the syndrome and its components. While at this time there is no consensus among members of the scientific community as to a specific definition for EMS, it is clear that the syndrome is closely linked to, and may be caused partially by, obesity.  But the cause and effect dynamic between EMS and obesity is one of the factors that’s still up for debate.

Not long ago, veterinary medicine insisted that horses do not get diabetes. Today EMS is often referred to as “insulin resistance”, which is essentially the same as type II diabetes in humans. But, in horses it’s not quite as simple. There are horses diagnosed with EMS symptoms that do not test positive for insulin resistance. Conversely, there are some horses with insulin resistance that do not exhibit EMS symptoms. What this means is that not all horses with a blood sugar problem will exhibit typical EMS symptoms and some horses will exhibit the symptoms even before they officially become insulin resistant.

So, now that the definition of EMS is clear as mud, let’s look at some of the theories about what could be causing the growing epidemic of EMS in domestic horses:

What Causes EMS?
It has been shown in both animal studies and human studies (see links at end of this article) that selenium interferes with insulin signaling. So, some believe that the addition of selenium in many commercially available horse feeds and supplements may be associated with the appearance and increase of EMS symptoms in horses.

Another theory is that slow bowel movement caused by forage restriction, which massively disrupts the intestinal flora, is resulting in equine livers that are often overloaded with toxins. Poor liver function leads to stress to the immune system which, among other things, can lead to considerable stress in the metabolism of the horse.

Too much sugar being fed in the form of commercial cereal grains and horse treats is also believed to promote the development of insulin resistance via high blood sugar fluctuations.  Insulin resistance and pro-inflammatory activity of the fat tissue were documented to play major role in equine metabolic syndrome (Carter et al., 2010).

Metabolic problems affect almost all systems of the horse. Although we may see obvious outward symptoms such as a cresty neck and laminitis it’s important to remember that there is much more happening within the body, and those issues/imbalances may or may not be recognized as stemming from the same problem that caused the EMS symptoms.

For example, it is important to pay attention to the level of inflammation present in a horse’s body generally because this impacts how a particular horse might respond to stress or change. If a horse is showing signs of allergy for example, this could be an early warning sign of metabolic issues. These horses also tend to have exaggerated responses to any changes, even small ones, in environment, feed, hoofcare, etc.

Treatment and Prevention of EMS
The administration of pharmaceutical drugs without relevant changes to diet and overall management of the EMS horse is usually unsuccessful. A massive restriction of sugar, starch and nonstructural carbohydrates (NSC) in the diet, combined with a high intake of digestible fiber and medium chain triglycerides (MCT), is often recommended. Cool Stance (coconut meal feed) fits this bill.

Recently, the practice of limiting grazing time for horses with EMS has come under question because research with a variety of species has repeatedly shown that stress tells the body to hold on to fat.  And, restricting forage (especially grazing time) is the most chronically stressful thing you can do to your horse.

Deprivation of hay overnight is also detrimental. Researchers from Louisiana State University, found that mares having enough hay during the day but deprived of hay overnight showed the greatest degree of insulin resistance.

Getting aggressive about reducing inflammation can be very beneficial for both treatment and prevention. Boost your horse’s diet with antioxidants, anti-inflammatory herbs (including products like Turmericle), key minerals (MBC is a great product to consider!), and the right balance of omega 3s to 6s, preferably from supplements that provide wholesome ingredients, without the use of added preservatives.

Work with a nutritionist or use a service like FeedXL to ensure that your horse’s feeding regimen includes a balanced intake of vitamins and minerals.  Imbalances of magnesium, copper, zinc, chromium, iodine, and selenium can impact insulin resistance.

Consider limiting or eliminating the amount of time your horse spends in a stall. Exercise and movement are critical to your horse’s well-being. Researchers at the University of Queensland, Australia demonstrated that exercise improves insulin sensitivity and reduces cytokine production. And, researchers at Virginia Intermont College found that pastured horses were just as fit as horses who were kept in stalls and exercised five days per week.

Support your horse’s hindgut (cecum and large colon) because its microbial population is responsible for digesting the fiber in your hay and pasture. The majority of your horse’s immune function is in the hindgut, preventing the overpopulation of detrimental organisms. Many horses benefit from fermentation products and other “food” for existing microbes such as FORCO, especially during any time of stress or transition.

Slow down your horse’s intake. Horses in a natural setting do not eat large amounts at one time; instead, they graze on small amounts of forages, walking great distances to find that next tasty morsel. Hay should be offered in small piles or in slow feeders in many locations to encourage movement and natural seeking behavior. If your horse is stalled, you can place a slow feeder net or container (choose one that does not damage the teeth or soft tissues) inside the stall in two locations. And always keep them full! These are designed to stimulate saliva flow and satisfy the horse’s need to search and pull hay from the openings.

In summary, although the exact definition and causes of EMS are still unclear, allowing your horse to “be a horse” and to live as naturally as possible will lessen the likelihood he will develop EMS.  It’s also what will give him the best shot at recovery.

Resources: 

http://www.sciencedirect.com/topics/agricultural-and-biological-sciences/equine-metabolic-syndrome

https://www.jstage.jst.go.jp/article/jcbn/48/1/48_11-002FR/_pdf

http://www.equinews.com/article/selenium-for-horses-how-important-is-it

https://www.horsecity.com/2017/07/17/forage-deprivation-keeps-your-horse-fat-the-research/

http://www.horsetalk.co.nz/2017/01/03/insulin-resistant-horse-health/ – Vz5EC1j9XwpEhL44.99

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