Texas Equine Veterinary Association

www.texasequineva.com • 21 Additional tips: • Soak hay for at least 60 minutes before feeding to reduce the water-soluble carbohydrates in the hay. Be sure to remove hay from the water prior to feeding. • Divide calculated amount of daily hay into multiple small meals to avoid prolonged fasting • Have NSC analysis of hay performed and aim for a hay with a less than 10% NSC content if possible • Provide ration balancer to avoid vitamin/mineral/protein deficiencies • AVOID feeds high in NSC and fat Once a horse achieves a BCS of 5/9, certain adjustments can be made based on signs of laminitis and results of repeat tests of ID. See "Monitoring" below for more details. For lean horses (BCS 4-5/9), a low glycemic diet should be offered. As previously mentioned, hay analysis to ensure that a hay with less than 10% NSC is ideal. The amount of hay fed will depend on the horse's current condition as these horses can occasionally be maintained on 1.5–2% of body weight on an as-fed basis as long as the glycemic index is low. Additional tips: • Goal is a low NSC, high fat, high quality fiber diet • Low starch grains, beet pulp, soy hulls are an additional option to low NSC hay • Provide ration balancer to avoid vitamin, mineral/protein deficiencies Exercise is recommended unless signs of laminitis are present or if there are any concerns for lamellar instability or other causes of lameness. Although the amount, intensity, and frequency of exercise can affect the degree of weight loss, any type of exercise including turnout (with restricted grazing) can be beneficial for animals with insulin dysregulation. Ideally, ID horses undergo directed exercise programs as long as lamella are stable and lameness is not present. 1,3 Low intensity exercise (on a soft surface) • Achieve heart rates of 130–150 beats per minute (bpm) for greater than 30 minutes three to five days per week • This can be achieved at a trot or canter on a lunge line • Low intensity exercise is best for horses that have had a previous episode of laminitis albeit stable at the time of exercise Moderate intensity exercise (on a soft surface) • Achieve heart rates of 150–170 bpm for greater than 30 minutes five to seven days per week. • This can be achieved by canter or fast canter under saddle or on a lunge line • Alternative option is 15 minutes of fast trotting five times per week A variety of heart rate monitors are now available for horses. One option being the Polar equine heart rate monitor that comes with an elastic surcingle and can pair to a smartphone application. Horses should be monitored for signs of lameness at all times. If any signs of laminitis occur, exercise should be discontinued until laminitis is well managed. Medical therapy can be implemented if diet and exercise are unsuccessful at reducing BCS and improving ID. Medical therapy should never be used as a substitute for appropriate nutritional management.1,3 • Levothyroxine—A thyroid supplement aimed to accelerate weight loss and improve insulin sensitivity. Powder products are available (Thyro L) and can be given in food at a 0.1 mg/kg dose once daily. Nutritional management should continue while the patient is receiving the levothyroxine. Once the patient has achieved appropriate weight loss, the dose should be gradually reduced over a period of two to four weeks before discontinuing. It is not recommended to keep a horse on levothyroxine for greater than six months. • Metformin – An oral compound aimed to reduce postprandial hyperglycemia. This product is used for the treatment of human metabolic syndrome and type 2 diabetes. The product is available in tablet form and can be given by mouth 30–60 minutes prior to feeding at a 30 mg/kg dose up to every eight hours. In order for the drug to be effective it MUST be administered prior to feeding. Research regarding the exact effects of metformin on insulin resistance in horses is still ongoing. At this time, there is no clear recommendation for duration of metformin treatment but one source recommends a period of two weeks (reference). • Sodium-glucose co-transporter 2 inhibitors—An oral compound that acts to reduce blood glucose by means of urinary excretion. Two drugs are currently available, canagliflozin and ertugliflozin; both are labeled for the treatment of diabetes mellitus in humans. The drug is expensive and should be reserved for horses that do not respond to any of the above recommended management changes. It can be given by mouth at a dose of 0.3 mg/kg every 24 hours. No recommendations currently exist for the duration of treatment but in general, administration can be considered appropriate until ID is better controlled and/or until the drug becomes too cost prohibitive. The drug should not be used in horses with marked hypertriglyceridemia. • Others—Multiple other drugs have been investigated for the treatment of EMS, including, pioglitazone, chromium, and magnesium. For the general practitioner, the three aforementioned drugs seem to be the most practical if medical therapy is needed to supplement nutritional and exercise management. Treatment and management of laminitis is of great importance but is beyond the scope of this article. The reader is directed to the references for additional information regarding endocrinopathic laminitis and its management. 12,13 MONITORING – Insulin dysregulation should be monitored regularly. Once dietary restrictions are initiated, testing should be performed monthly until adequate weight loss has been achieved, then every six to 12 months depending on the horse's state. Testing can consist of the OST as previously described, or measuring fed insulin concentrations while the horse is receiving the recommended diet. If ID is better controlled (insulin concentrations within normal limits with either of aforementioned tests), the horse might be able to resume some pasture grazing. Return to restricted grazing can

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