Equine Metabolic Syndrome (EMS) is a disease similar to Type 2 Diabetes in humans. Normally, when horses eat a meal, they absorb sugars from their intestines, causing an increase in blood sugar levels. In response, the pancreas secretes insulin, a hormone that helps glucose get into the cells where it can be used for energy. The circulating blood sugar thus goes back to a lower level. This is an active balancing mechanism.
In the EMS patient, the body becomes much less sensitive to insulin, and ever increasing amounts are required to return the blood sugar to normal. This lack of sensitivity to insulin causes a number of problems. First and foremost, there is significant evidence that chronically elevated insulin levels directly damage the lamina in the feet, causing founder. In addition, there is strong evidence of immune system damage, and increased fat deposition both externally (the crest, loin, and tail head), and internally, particularly in the liver. The internal fat is particularly damaging, because it releases various other compounds that amplify the insulin resistance.
Management of EMS in the horse is centered on dietary changes and increased exercise. Exercise is the best insulin sensitizer available. Riding 4-5 days a week for an hour is great therapy for both horse and owner. Each session should work up a sweat.
Modification of the diet to limit intake of soluble sugars is very helpful. There are broadly two types of sugars available in the horse’s diet. These sugars are classed as soluble and insoluble. Soluble sugars are things like glucose and fructose and taste sweet. Insoluble sugars are more like pasta. It is possible to measure the soluble sugars in hay and grain samples. The goal is to have less than 10% soluble sugars in the horse’s diet. Hays with more than 10% soluble sugars can be soaked for 30 minutes to remove the soluble sugars. Remember to pour out the water before you feed the hay! There are sources of low soluble sugar hay pellets and pre-formulated rations available from Purina, Nutrena, and others.
The other essential part of dietary management is total caloric intake. EMS horses need to be a little on the thin side. Normal recommendation for total caloric consumption is 1.5 pounds of feed (total hay and grain) per day per hundred pounds. If your horse is over weight, a weight loss program should be devised to get his weight down. Remember, less fat = less insulin resistance.