Feeding and Management of the Overweight and Insulin Resistant Equine
Obesity – the epidemic is rising in the equine population similar to what is happening with our human population. Higher quality nutritional products and improved pasture management over the years has made it easier for horses to get fat and stay that way. Also, just as their overweight human counterparts, many horses get little to no exercise on a daily basis. Overweight horses are prone to many disorders including organ failure, intolerance to exercise, higher oxygen requirements, problem pregnancies, developmental orthopedic disease and laminitis, just to name a few. It is also speculated that a horse or pony that has been hefty for most of its life will be predisposed to developing Cushing’s disease as a geriatric. Cushing’s is a condition where a tumor or enlargement on the pituitary gland causes a dysfunctional metabolism.
Horses of all ages that are overweight can also become insulin resistant, meaning when any amount of starch or sugar is consumed, the horse will not be responsive to the effects of insulin, the hormone responsible for regulating carbohydrate and fat metabolism. As the body’s cells become less sensitive to insulin, the body responds simply by producing more insulin. These higher levels serve to regulate blood glucose for a while, but eventually the body’s cells fail to respond even to these increasing levels and eventually lead to total failure of the insulin-producing cells. This condition is similar to diabetes, one of the most common problems facing chronically overweight humans, and was once thought to be nonexistent in the equine world.
All horses can develop insulin resistance but certain breeds are more predisposed to the condition. Cold blooded and pony breeds seem to pick up weight the easiest, and therefore these breeds should be monitored and managed for proper weight early in life. It is easier to prevent insulin resistance than to deal with a horse that already is insulin resistant and will have to be treated as such for the remainder of its life. These horses usually have fat deposits that are a result of the body’s inability to use glucose, and it is inappropriately stored as fat. It has been theorized that this fat storage ability may have helped these easy keepers outlive their skinny herd mates. The ability to store fat while surviving on minimal amounts of feed is advantageous to a horse during drought or famine. Additionally, fatter horses would have had a better chance of survival and went on to reproduce, so the genetics of these horses may have been selected over those of other non-insulin resistant horses.
What do we do to prevent our horses from becoming insulin resistant?
- More Exercise: Insulin resistance is reduced by exercise and any amount or increase will be useful.
- Manage Hay: If you have a horse you suspect is or could become insulin resistant, select forages that have been analyzed and are known to contain low levels of sugars, fructans and starches. Contrary to popular belief, grass forages are generally higher in sugars, starches and fructans than legumes such as alfalfa. However, legumes are higher in calories so need to be used sparingly. Forages with lower calorie levels are actually better for the insulin resistant horse because they can eat more of it throughout the day to avoid insulin dips and spikes without gaining too much weight. You can always add in protein, vitamins and minerals with a supplement.
- Manage Pasture: Don’t allow obese horses to graze unrestricted on pasture, especially during sunlight, this is when the plants are photosynthesizing. During the day is when the sugar content in the leaves and stems is the highest (the plants use the sugars for energy while trying to grow). Limit grazing time to overnight or early morning and strongly consider the use of a grazing muzzle (a muzzle with small holes through which the horse can consume much smaller amounts of grass) or put your horse in a dry lot. This is preferable to keeping the horse stalled on a continuous basis.
- Manage Feed Concentrates: It is imperative that the insulin resistant or IR prone horse be fed low sugar and starch concentrates and supplements if feed is needed in addition to hay. Products selected for the insulin resistant horse should contain as little fat as possible. These horses already have impaired fat metabolism due to the high levels of insulin they secrete (insulin suppresses fat metabolism and supports fat deposition). Many insulin resistant horses will begin to have heat in the hooves if they are fed rations that contain added levels of fat and high levels of starches and sugars (this signals the beginning stages of laminitis), so stick to a product that supplies protein, vitamins and minerals with high levels of fiber and lower fat. Triple Crown Nutrition carries two supplements suitable for easy keepers