Rumor Buster: Insulin Madness

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Insulin resistance is a metabolic condition with some serious consequences, and Horse Journal first brought it to your attention in our magnesium article in January 2001. The recognition of insulin resistance has grown rapidly since then, and with that has come the usual a rash of magazine articles on the subject and even some special feeds. It’s good that the word is getting out, but it’s not good if you let unjustified concerns over insulin resistance cause panic and upheaval.

Insulin resistance involves problems when the horse has handling high dietary intake levels of sugars or starches. The results are easy weight gain and often laminitis, among other things.

• Not every easy-keeper horse is insulin resistant, and not every insulin-resistant horse is overweight.

• The only way to know for sure if your horse or pony is insulin resistant or not is to have blood work done. Most experts recommend a morning blood sample for insulin and glucose testing, with nothing but grass hay to eat since the evening before.

• Grain is not poisonous. Feeding your horse grain will not make him insulin resistant.

• Being overweight might create a degree of insulin resistance in horses, but problematic insulin resistance is more likely a part of the individual horse’s genetic makeup than his weight. However, you should avoid all the negative consequences of obesity by not overfeeding your horse and making sure he gets plenty of regular exercise anyway.

• Loafing in a field all day is not exercise. Formal exercise (riding, longeing, driving and so on) is also an excellent way to control/reverse insulin resistance.

Equine Low Carb
It would be difficult not to have noticed the explosion of “low carb,” “low grain,” “safe” feeds on the market. It’s happening with pet foods, too. If this all sounds like the current low-carb diets, it’s because it’s supposed to. Marketing executives know how to tweak concerned animal owners.

Don’t get us wrong. Insulin resistance is real, both in small animals (cats especially) and in horses, but the flashy feeds might not be the answer. Instead, consider:

• A diet based primarily on low sugar/starch hay with just enough soaked plain beet pulp to get needed supplements in is the ideal way to feed a horse or pony that actually is insulin resistant.

• Exercise is a potent weapon against insulin resistance, every bit as important and effective as the diet control.

• Many, if not most, “low carb” horse feeds aren’t actually low enough for the horse that is truly insulin resistant. Read the label ingredients list (see June 2004).

• Although it’s true that adding fat to a meal decreases the degree of glucose rise after feeding that single meal, the safety of long-term high-fat feeding to insulin-resistant horses is unknown at this time.

In other insulin-resistant species, high-fat diets worsen the condition. Many of the new feeds boost the calorie content by adding fat to the content, so they’re not appropriate for weight loss and may not be a good choice for an insulin-resistant horse.

Bottom Line
Some feed companies are genuinely trying to come out with a product that meets the needs of the insulin-resistant equine. Still other manufacturers fall short on their attempts because the sugar and/or starch contents in the feed are too high. And some manufacturers are just trying to cash in on the trend.

Don’t take feed claims at face value. Consult with a veterinarian or nutritionist that’s familiar with equine nutrition, insulin resistance and with the tolerance of your own horse, then ask the feed companies the hard questions about the feed’s contents.