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Nutritional Management of Horses With Metabolic Disorders

In the past three weeks, I have been writing about two of the most often diagnosed metabolic disorders of equines… Equine Cushings Disease or PPID (symptoms and treatment), and Equine Metabolic Syndrome. Getting a diagnosis is the first step. What are the rules of the road for the nutritional management of horses or ponies with metabolic disorders?

Have you seen the TV commercial about the insulin pump, featuring the “fluffy” guy on a cruise trying to decide what to eat at the buffet? The commercial talks about the “no” and “know”. The guy needs to know his blood sugar level so that he knows when to say no. In that case, that guy is in charge of his own diet and is responsible for his decisions.

We are responsible for understanding our animals’ nutritional needs. When I was in practice, I saw way too many overweight pets. On farm calls while in veterinary school, I saw way too many overweight horses.

Horses in the wild must move constantly to find forage. This article from UC Davis explains the shift in conditions that has occurred for our present-day equine companions.

This disorder often affects a subset of horses bred to survive in harsh climates, including ponies, donkeys, Arabians and mustangs. These breeds utilize glucose very efficiently to ensure that they have plenty of energy reserves when food is scarce. When these “thrifty” horses are placed in an environment where they have access to an abundance of carbohydrates and do not get as much exercise as they would in their ancestral habitats, they suddenly consume too many calories.

Amy Young, UC Davis Veterinary Medicine Center for Equine Health

Alan’s mare Sadie might currently live in the desert just as her ancestors did… but she most definitely doesn’t have to scrounge for feed!

A horse diagnosed with Equine Metabolic Syndrome probably is a fat horse. (However, not all horses diagnosed with EMS are clinically overweight, and not all overweight horses develop EMS.) As mentioned in Part Three of this series, EMS is a disorder of insulin production and response. Horses with EMS become resistant to the effect of insulin; therefore, the body produces more in an attempt to drive glucose into the cells. Understanding how to feed an EMS horse requires an understanding of different types of carbohydrates.

Structural vs non-structural carbohydrates

A structural carbohydrate is a complex sugar that takes more time and energy to break down into a useful source of fuel. This digestion occurs as a result of bacterial action in the hindgut of the horse and doesn’t result in the rapid sugar spike that is seen with non-structural carbohydrates (NSC) or simple sugars. Starches and simple sugars break down into glucose in the small intestine and cause a sugar spike, followed by an insulin spike.

Metabolic disorders

Horses diagnosed with EMS need a diet that is low in non-structural carbohydrates. The generally accepted rule of thumb is to try and keep the NSC level to less than 10% of a horse’s daily intake. It is a misconception that horses with EMS need a “low-carb” or “carb-free” diet… they just need a specific type of carbohydrate. A diet composed of <10% NSC helps to maintain a steadier insulin level.

The suggested amount of forage to feed is 1.5% of the horse’s desired body weight per day. Vitamins and minerals need to be supplemented by a compound that doesn’t add additional calories. No pasture access and no other source of carbs should be given. If the horse doesn’t lose weight, hay can be provided at a rate of 1% of the body weight, but no lower than that. Nature doesn’t like a “starving” horse, so dropping it lower than that puts nature in conservation mode, which negatively impacts the use of fats and the production of insulin.

How can you tell what you are feeding?

Finding a consistent source of low NSC hay is key to managing an EMS horse. Equi-Analytical is a laboratory that offers multiple options for testing forage. The best course of action is to actually know the nutritional content of what you are feeding. Soaking hay in water has the potential to lower the carb level, but it happens to a varying degree. A better option is to minimize the variability of the feed by testing it and feeding accordingly.

Beet pulp is a good source of calories with a low sugar content. Also, adding a fat supplement can help with caloric intake if forage isn’t enough. (Re-Leve)

Exercise is also a key component to managing a metabolically challenged horse. Little Miss Sadie doesn’t just hang out in a lush Oklahoma pasture and eat herself silly anymore. She climbs the Rocky Mountains and the Dragoons of Arizona!

There is much more to understand about the nuances of feeding horses with Cushings or EMS. Is alfalfa good or bad? What types of hay are naturally lower in non-structural carbohydrates? Here are several excellent articles that go into more depth about exercise, types of sugars, supplements, forage testing, and general management of metabolically challenged horses.

Feeding Metabolic Horses: Risky Business or Simple Solutions

How to Feed Horses With Metabolic Challenges

Equine Metabolic Syndrome

EMS and ‘Low-Carb’ Diets: What’s Right for Your Horse?

Nutrition for Horses with Metabolic Disorders

Equine metabolic syndrome–dietary and medical management (Proceedings)

The last article is more technical and was written by the DVM we interviewed for our podcast. My podcast partner has been ill and that has delayed our launch. I will keep you posted!

Best wishes for a wonderful 2022! Gosh, I’m old!

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