Insulin resistance, obesity and Cushing’s disease all put your horse at risk for laminitis. The metabolic changes associated with these conditions require strict limitation of sugars and starches in these horses. Being fat can also affect fertility and greatly increases joint stress.
While horse owners try all kinds of things to keep these horses healthy — from drugs to shoes to “miracle” supplements — nothing is going to be a real fix if you don’t get back to the basics: diet.
A few years ago, beet pulp was considered a bad choice for horses with metabolic disorders because of its high NFC (nonfiber carbohydrates) content. However, we now know that most of that NFC is actually pectin, a soluble fiber that’s removed by the same analysis techniques that pull out sugar and starch. In fact, beet pulp without molasses is the best thing to feed these horses. Plain beet pulp has the lowest glycemic index of common equine feeds, lower even most than grass hays.
The glycemic index of a feed is how high a spike in glucose/sugar is produced after the horse eats it. And you don’t want a sugar spike in these horses any more than you do in a human diabetic. As much as 30 to 40% of the horse’s diet by weight can come from beet pulp. At higher amounts, hay intakes may drop off because beet pulp is filling.
Because beet pulp has a calorie level higher than grass hay, if the horse is overweight, substitute beet pulp for hay at a rate of 1 pound of beet pulp (weight before soaking) for each 2 pounds of hay removed. For normal-weight horses, feed 1 to 1.5 pounds of beet pulp for each 2 pounds of hay, adjusting as needed to hold the correct weight. For horses that are underweight, substitute on a pound-for-pound basis to encourage weight gain.
Stabilized flaxseed meal and rice bran are good choices as grain substitutes in terms of their effect on blood sugar and insulin, but they’re both high in fat, which may be a worry. Feed these products only at levels necessary to provide essential fatty acids (1 to 2 oz. each). If your horse’s weight is OK, you can feed up to 6 oz. a day to help with mineral balances. We recommend a rate of 2 oz. per 1 pound of beet pulp fed.
Be careful with alfalfa hay, which can cause laminitis flare-ups in some horses. The mechanism for this isn’t clear — and technically it shouldn’t — but the fact of the matter remains that some horses are sensitive to it. If your horse tolerates alfalfa well without foot pain, you can include it up to 20% of the hay ration.
Grass hay has always been the staple of the diet for overweight and laminitic horses. However, research by agricultural consultant Katy Watts presented at the 2003 Laminitis Conference showed that not all grass hays are equal when it comes to their safety for these horses. A safe level of sugar and starch in the hay appears to be 10% or lower. Most strains of Bermuda grass have the lowest levels, making it your first choice if you can get it. Timothy is second.
Orchard grass, oat hay and other grain hays are the worst choices. Their sugar content can be close to 20% or higher. Other factors that influence the sugar content of a hay include growing stresses and rapid curing conditions.
And don’t underfeed either. The best results are obtained when the horse is fed hay at a rate of a minimum 1.5% of his ideal body weight. For example, if the horse currently weighs 1,200 pounds but should only weigh 1,000, feed him a minimum of 15 lbs. of hay a day. Cutting back to near starvation rations can actually worsen insulin resistance and is rarely effective in getting weight loss. This also cuts back too far on the protein and minerals the horse needs.