Question
I have an 18-year-old Fjord mare with insulin resistance. She’s on limited pasture, ration balancer, and glucosamine/chondroitin, which I recently read was not a great choice for insulin-resistant horses. Should I be feeding her other supplements for the metabolic issue? Also, I’d like to know how much exercise she should be doing to help ward off complications of the insulin resistance.
Answer
Evaluating both exercise and diet when trying to achieve metabolic equilibrium is a great idea. A general recommendation would be 30-40 minutes of structured exercise daily, but that is dependent on soundness, age, fitness, and myriad other factors. Discuss with your veterinarian an exercise program that would be best suited for your mare.
Regarding diet, additional information would help me evaluate your mare’s situation. What is your mare’s current body condition score? Does she need to lose a significant amount of weight? How much and what kind of hay does she consume in addition to pasture? Does she wear a muzzle in the pasture?
A ration balancer is a good choice for an easy keeper because it provides the necessary nutrients without excess calories. You didn’t mention how much ration balancer she gets currently. If it is below the minimum feeding rate based on the feeding directions, she may need a more concentrated micronutrient supplement.
Horses that need to lose a significant amount of weight may do best with a supplement like Micro-Max that provides the nutrients missing in forage. Micro-Max contains highly digestible forms of natural-source vitamins and chelated minerals. Depending on weight, 2-4 oz daily will provide the nutrients necessary for optimal health. Unlike other micronutrient supplements, Micro-Max is highly concentrated. Micro-Max doesn’t contain added protein like the balancer pellet because most mature, idle horses consume enough protein to meet their needs through forage. You can continue with the current feed if she is consuming the recommended amount to meet nutrient requirements. In Australia and New Zealand, look for Gold Pellet.
You pose a common question about the use of oral glucosamine in horses with metabolic diseases. Many people fear that glucosamine may enter the glucose pathways that influence insulin sensitivity and glucose uptake. In human studies, the only time there was a slight increase in the plasma glucose concentration was through intravenous glucosamine administration at 500-1,000 times the concentration expected in oral administration. Oral administration, even at high doses, did not show any effect on glucose in humans.
In horses, the absorption rate of orally administered glucosamine is lower than humans, which is why the source of ingredients and amount fed are so important. With that said, if you feed the proper levels and source of glucosamine (research shows 10,000 mg for a 1,200-lb or 500-kg horse) to achieve absorption for improved joint health, glucosamine is not likely to ever reach blood concentrations that would interfere with glucose metabolism.
In an effort to improve glucose tolerance and insulin sensitivity, you should consider omega-3 fatty acid supplementation with EO-3. Kentucky Equine Research has found that supplementation with DHA and EPA, two specific omega-3s, has been beneficial for metabolic horses, including those with insulin resistance. Marine-derived DHA and EPA are the most beneficial sources of omega-3s. Supplementation with omega-3s, like those found in EO-3, reduces inflammatory conditions associated with metabolic conditions and improves glucose tolerance. EO-3 is a deodorized, single-source fish oil designed to be fed at 1-2 oz (30-60 ml)/day. We recommend gradual introduction to feed by starting with less than 0.5 oz (15 ml) and working up to full dose. Average-sized horses with inflammatory conditions or metabolic disease would benefit from 2 oz (30 ml)/day.
