Equine Metabolic Syndrome and Founder

By: Mark Hale DVM

Bolivar, MO

            Spring brings nice weather for trail riding, good fishing, and green grass. It is the latter that increases the risk of one of the most common problems of horses, "grass founder".

            Founder is a term used to describe inflammation of the inside structures of the hoof called "sensitive laminae". This inflammation can be caused by a variety of circumstances, including grain overload, cold water ingestion, uterine or other severe infections, and hard surfaces. In my experience grass founder, however, is by far the most common type seen in this area.

            Grass accumulates starches or sugars by photosynthesis. It is these substances that provide energy to a grazing animal. These are in grasses all the time but become much more concentrated as the lush spring growth begins. Cool season grasses such as fescue can also produce a large amount of starch in the fall. Pastures with legumes, such as clover and alfalfa, are more likely to cause the condition. Horses that develop grass founder are usually overweight and have a heavy crest on the neck. Often they have repeated small bouts of laminitis that weakens the laminae and allows chronic changes in the feet. The owner is oftentimes unaware that there is a problem until a lot of chronic damage is already done.

            In the last few years researchers have found that this is very similar to a human condition called "metabolic syndrome". This syndrome in humans includes insulin resistance, hypertension, and obesity. It is this insulin resistance that causes diabetes in many individuals. In horses, metabolic syndrome (MS) is characterized by obesity, insulin resistance, and the risk of laminitis. Therefore it is imperative to identify these horses, and institute corrective and preventative measures before serious and potentially life-threatening founder occurs.

            The key therapeutic objective is weight reduction. Controlled food intake and physical conditioning have shown significant improvements in insulin resistance. The most important aspect of feeding a horse with MS is limitation of the soluble carbohydrate portion of the diet. Simply eliminating grain products and using a hay-only diet may result in dramatic improvements in laminitis pain in just a few days. The safest feedstuffs in maintaining blood glucose are beet pulp, rice bran, and Bermuda hay. Laboratory analysis of hay samples can be beneficial.  Free-choice access to unlimited grass should be avoided in horses with MS. Use of grazing muzzles are an option in certain instances. Owners of these horses should monitor daily for weight gain, a change in abnormal fat deposits (e.g., cresty neck), and early signs of laminitis (e.g., less spontaneous movement, reluctance to turn in a small circle). I have seen dramatic improvements in a horse's laminitis and quality of life with adequate weight loss.

            If you have questions about your horse's health and nutrition, please make an appointment with your veterinarian. Founder can be a very painful, expensive, and life- ending problem that is much better to prevent, than treat.