Feeding the Metabolically Challenged Horse
Amanda Blanton, DVM
Establishing an appropriate feeding plan for a horse with an endocrine disorder (PPID/Cushings disease, Equine Metabolic Syndrome, and/or Insulin Resistance) can be challenging and is tailored to each horse’s specific situation. As a result, it is important to discuss your horse’s endocrine status and nutritional needs with your veterinarian and to closely monitor your horse’s body condition, appetite and presence of any foot soreness (in those horses that are at high risk of developing laminitis.)
The goals in feeding a horse with an endocrine disorder are to decrease body fat in obese horses and to avoid feeds that will worsen insulin resistance (IR.)
Overweight horses (body condition score 7-9) require a strict program of dietary management and exercise. It has been shown that the risk of developing insulin resistance (IR) increases as the length of time a horse is overweight increases, and studies have shown that IR horses are more likely to develop laminitis. As a result, it is imperative to get the excess weight off these horses. Obese horses should be fed a diet of hay plus a vitamin and mineral supplement. Since they will be receiving no other calories, these horses should be fed enough hay to meet their energy requirements: 1.5-2.0 % of their body weight. This is equivalent to 15-20 pounds of hay per day for a 1000 pound horse.** Obese horses that are not actively laminitic should also be exercised daily to further reduce weight.
Avoiding Insulin-Resistance Causing Feeds
The key here is to avoid excess sugars and carbohydrates. Most sugars in a normal horse’s diet come from pasture grasses. As a result, when managing IR ponies or horses, you must restrict or eliminate pasture from the diet. Options for pasture restriction include strict dry lots, use of a grazing muzzle, free grazing for 1-2 hours a day and strip grazing with electric fencing. It has been shown that grasses are highest in sugars during dynamic stages of growth. Therefore, it is important to avoid grazing during the following times of year: spring (when grass is growing quickly and turning green,) early summer (when grass is starting to dry out,) following heavy summer rains (when grass is rapidly growing,) and fall (when grass is entering winter dormancy.) Sugar content in pasture grasses also varies with the time of day. Sugar content is low early in the day and high later in the day. As a result, it is best to graze horses with metabolic issues in early morning versus late afternoon. However, since each case is different, consult with your veterinarian to determine the best option for you and your horse.
Unlike the obese horses, some horses with endocrine disorders (lean horses in regular work and/or ribby horses with regional adiposity) will require supplemental calorie sources. How do you increase caloric intake without increasing the sugars and carbs that can lead to IR? If your horse is one of these and needs to be fed a concentrate, look for those feeds that are low in sugars and carbohydrates. Dividing the feedings into smaller, more frequent meals is a great way to decrease your horse’s natural glycemic response to each meal. It is also good practice to feed hay before concentrates to slow the transit from the stomach to the lower digestive tract where many carbohydrates are broken down into harmful sugars. You will also want to feed a hay that is <12% non-structural carbohydrates. To achieve this, you can send away hay to be tested or you can soak your hay for 60 minutes in cold water (30 minutes in hot water) prior to feeding it to your horse.
Other additives that may be used in tailoring a diet specific for your horse’s needs include rice bran, rice bran oil, or corn oil as high calorie, low carb supplements. Molasses free, soaked beet pulp is another great way to add calories and fiber to the diet while avoiding carbohydrates. Again, ask your veterinarian for recommendations to meet your horse’s specific requirements and tastes. Remember to make all feed changes gradually, at least over 10-14 days. And don’t forget to stay away from high sugar treats (no sugar cubes!)
As you can see, there are many factors to consider when establishing a feeding plan for a horse with a metabolic disorder and it can be challenging to create a plan that is feasible for you and palatable for your horse. However, it is very rewarding to see the results when an appropriate feeding plan is couple with exercise and appropriate medication (if needed.)
1. Frank, Nicolas. How to Feed Horses with Endocrine Disorders. AAEP’s 53rd Annual Convention Proceedings. 2007:186-192
2. Gordon, M.E. et al. The effects of dietary manipulation and exercise on weight loss and related indices of health in horses. Longview Animal Nutrition Center, Land O Lakes Purina Feed, Gray Summit, MO.
3. Gordon, M.E. The Effects of Nonstructural Carbohydrate Content and Feeding Rate on Glucose and Insulin Response to Meal Feeding in Equine.
** TREES note: Feeding only hay may not be possible in elder horses with advanced dental problems. Talk to your vet about finding a suitable replacement.
For more on pasture in relation to metabolic disorders visit SaferGrass.org