July 2015 - Whoa There!
Written by Allison Enriquez
Thursday, 02 July 2015 01:54
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Mustang owner learns first hand how to keep equine metabolic syndrome in check.

by Allison Enriquez

I can remember the moment when my vet first became alarmed.

It was six years ago and my Mustang gelding, Rebel—who was then 17 years old—had an abscess and I had called in my new vet just to make sure he was okay.

Rebel, around the time he was diagnosed with EMS. As you can see, his crest is quite large.

But my vet took one look at Rebel’s stocky frame and enormous crest and said, “I would like to run some tests.” Rebel’s crest—which had been large all his life—was larger than it had ever been, a fat deposit that signaling to my vet that Rebel may have insulin resistance.

When I heard the dreaded words “run some tests” I was immediately concerned and agreed, hoping that everything was fine.

In the next few weeks I was hit with some shocking test results: X-rays of Rebel’s hooves revealed a slight case of laminitis in his right hoof and blood work indicated that he was insulin-resistant.

Finally, my vet diagnosed Rebel with equine metabolic syndrome, commonly referred to as EMS. Calmly, he told me that while EMS isn’t curable, it is manageable and above all I would need to change Rebel’s diet immediately and that he should not graze on fresh grass.

If left unchecked, my vet warned me that Rebel’s laminitis could become more severe and he could possibly founder, which would mean he would need to be euthanized.

I was crushed by the diagnosis, and didn’t know how I could keep Rebel away from our long afternoons spent with me listening to him peacefully graze on fresh grass beside me.

With the help of independent equine nutritionist Dr. Clair Thunes Ph.D., I discovered how nutrition can help or hurt a horse with EMS, and what I could do to help Rebel live a healthy life.

Understanding EMS

EMS commonly affects ponies and hardy horse breeds, often called “easy-keepers.” This syndrome usually occurs around the middle of a horse’s life, from 8 years old and up. While some other diseases have been confused with EMS—namely Pituitary Pars Intermedia Dysfunction (also known as PPID or Cushing’s Disease)—which has symptoms like insulin resistance, laminitis, increased drinking and urination, fat deposits and delayed coat shedding, EMS is strictly defined by three distinct characterizations: insulin resistance, obesity and laminitis. Typically, most veterinarians run diagnostic tests to find out if a horse has EMS or not.

Rebel before he was diagnosed, when his crest wasn’t as out of control.

Though some vets can prescribe certain medicines for EMS, the right diet and fitness regime are significant factors to managing this syndrome. According to Dr. Thunes, a horse with EMS needs to have a reduced intake in starches and sugars.

This means horses with EMS should not graze on fresh grass, receive traditional high-starch feeds or be fed treats like apples and carrots. Hay also needs to be monitored; some try to find low-carb hay or barns can run tests to find the starch and sugar levels in their hay. For those who don’t test their hay, soaking it in water before feeding is advised to reduce soluble sugars.

However, Dr. Thunes warns not to reduce hay intake too much, stressing that owners should ideally feed 1.5 percent of their horse’s bodyweight a day, and, at very minimum, no less than 1 percent of their bodyweight a day.

“The horse’s digestive system is designed to eat plenty of forage; reducing intake too much negatively impacts digestive function. While reducing hay intake does help cut out calories you also cut out protein, vitamins and minerals.” Dr. Thunes said. “So you need to make sure that your horse’s diet is adequately fortified because you want all their systems to be working properly.”

Although there are ways to deal with a horse once they have been diagnosed with EMS, it is preferable to help prevent EMS by working to keep your horse in a normal weight range.

Maintaining Healthy Weight

Because many riders see their horse everyday they may not notice their constant weight gain. “That’s why I have my clients give their horses a body condition score every month.” Dr. Thunes said.

Paying attention to these small fluctuations is important because it may indicate metabolic problems. “Uneven distribution of fat, such as fat in the neck or in fat pads distributed over the body, are warning signs that something may not be right.” Thunes said. If owners see these signs, they should consult their veterinarian.

Another issue Dr. Thunes sees is owners who may feed their horses a bit too much because they worry about horses showing their ribs. This concern may have people view healthy horses as too skinny.

“Being able to see an outline of ribs doesn’t mean a horse is too thin.” Dr Thunes said. “You have to take it in the context of the whole horse.”

Lastly, owners can help prevent EMS through feeding in a way that better mimics a horse’s natural feeding cycle in the wild, where they vary in weight. Instead, owners can get obsessed with maintaining a horse’s weight and gradually the horse’s weight may increase until they become overweight.

“Owners don’t tend to let their horses go through the ebb and flow of weight loss and weight gain. Horses’ lose a little weight in the winter and gain it back in the spring. That sort of the fluctuation is okay.” Dr. Thunes said.

I have to admit, I was one of those people who didn’t let Rebel’s weight fluctuate. He was always an easy keeper who loved his food, and I never liked to take that away from him. Then, when Rebel was rehabbing from his abscess I still fed him the same amount of carb-heavy hay without minimizing it to compensate for the lack of exercise. These factors played a large role in Rebel’s weight gain, and resulted in his crest storing even more fat than usual (as a Mustang who was gelded late, Rebel always had a thick crest), a sign that my vet knew meant trouble.

Once Rebel was diagnosed, I was able to find a paddock that did not grow fresh grass and found suitable feed to supply him. I played with different amounts of hay and low-carb grain to find a feeding plan that brought Rebel to a healthy weight.

Though I’m sure Rebel did not like the reduction in starch and sugar heavy foods, I did notice that his physique improved and he slowly gained more energy on our rides.

Now, I understand a lot more about the disease and how to manage a horse that has EMS. Even though we can’t go graze fresh grass for hours, I am thrilled that my pony is healthy and happy.


Author Allison Enriquez is a lifelong rider and owner of the Mustang Washoe Rebellion, aka Rebel. The pair were active event and dressage competitors in the Bay Area, but more recently Allison is concentrating on riding for fun, including some OTTBs, and finishing her Masters in English Literature at Mills College in Oakland, where she lives.