Pasture

• When dealing with an insulin resistant horse, keep an eye on your pasture and know what kind of grass is planted there. Drought-resistant grasses and grasses designed for beef cattle often have higher amounts of non-structural carbohydrates (NSCs) such as sugars and starches, which are bad for your insulin-resistant horse.
  You will also need to keep your horse off of pasture during times of drought, or times of extreme heat or cold. Stressed grass will produce more sugar. Greening grass in the early spring and dying grass in the fall can also cause insulin-resistant horses to founder.
  
  

Hay

• You need to know what kind of hay you are feeding your insulin-resistant horse, and what percentage of NSCs--preferably 10 percent or less--the hay contains. Buy hay from dealers or producers who have tested their crops, or are willing to do so at your request. Also, the longer the hay was grown was before harvesting, the more likely the hay is to have a lower amount of sugar.
  If you already have a large amount of hay that hasn't been tested, you can send a sample to a laboratory yourself (check with your county agricultural extension to find out where to send the samples). A short-term solution, especially if you have only one insulin-resistant horse in your herd, is to soak out the sugars in the hay. Place the hay in a tub with a cinder block or something equally heavy on top to keep the hay compressed, then fill the tub with water. Soak the hay for about an hour, then remove the water. Most of the sugar should be removed with the water.
  
  

Grain products

• Your insulin-resistant horse is best served by feeding as little grain products as possible to keep up his weight. In some cases, even pasture alone contains too many sugars and calories for your horse. If your horse does need a grain product, find a pellet (avoid sweet feeds or any other type of feed containing molasses) that is low in NSCs. Many feed companies now offer low-starch, weight-management or "light" feeds for horses that are insulin-resistant "easy keepers." (Easy keepers are horses that stay at an ideal weight or become overweight on little food.) You should be able to find the NSC percentage on the packaging.
  Another option is to put your horse on a "balancer" pellet that consists only of essential vitamins and minerals. The rest of your horse's diet can come from hay and pasture. Usually this is best for horses that are fairly easy keepers