Skip to Main Content
Ask About Financing

What Is Equine Metabolic Syndrome?

What is EMS?

Equine Metabolic Syndrome consists of insulin dysregulation and a collection of other risk factors highly associated with increased risk of endocrinopathic laminitis. Many horses with EMS have increased body fat which can generalized and/or in specific regional areas (crest of the neck, shoulders, above the tailhead, and in the sheath/mammary glands). These horses are typically described as “easy keepers.” Other metabolic hormones may be inappropriately regulated in these horses, contributing to difficulty in losing weight. In older horses, EMS often coexists with another endocrine disorder called Cushing’s Disease (Pituitary Pars Intermedia Dysfunction).

EMS is caused by a combination of genetic and environmental factors. Donkeys, ponies, Mini horses, Morgans, Paso Finos, Rocky Mountain Horses, Saddlebreds, Warmbloods, and Andalusians tend to be genetically predisposed to develop this condition under the right circumstances, especially in certain family lines. Severity of the disease and risk level for laminitis depends on the level of contribution of genetic predisposition and environment. While we cannot change your horse’s genetics or cure EMS, there are many environmental management changes we can make to reduce your horse’s risk of laminitis.


  • Resting Insulin Concentration - The relative insulin levels in the blood are measured. This test should be run at least 4-5 hours after the last grain meal (hay/pasture is okay). Elevated insulin levels at rest indicate insulin resistance/dysregulation
  • Oral Sugar Test – If resting insulin concentrations are not clearly elevated, but we still suspect EMS, a dynamic test can be performed after a short 3-6 hour fast. Glucose and insulin levels are tested at multiple time points after a specific small amount of sugar is fed to your horse.
  • Body Fat Assessment – Body Condition Score, Cresty Neck Score, Body Weight (ideally on the scale at the clinic), and general physical exam can be used to assess your horse.
  • Hoof Assessment – Lameness exam, hoof testers, visual exam of the hoof for divergent growth rings, and radiographs of the feet can be used to asses current/ongoing and historical laminitis in your horse.

Feeding Management

The main goals of dietary management are aimed towards reducing carbohydrate and sugar intake, and in the case of horses with increased fat, total daily calories.

  • Do not feed any whole grains including sweet feed, oats, corn, or barley
  • Provide a vitamin/mineral supplement or ration balancer. Supplements include Northwest Horse Supplement, Horse Guard, or California Trace Plus. Ration Balancers include Purina Enrich Plus, Triple Crown Balancer, LMF Super Supplement. Triple Crown Lite is another good option. Be sure to follow the feeding instructions on the bag to ensure you are feeding adequate vitamin and mineral amounts for your horse’s body weight.
  • Do not allow access to grass, especially in the spring, late summer, and fall or to any lush grass at any time. If a dry lot is not available, use a grazing muzzle. Even an hour of grass without a grazing muzzle can be enough to trigger a laminitis episode.
  • For weight loss, feed 1.5% of current body weight in hay per day (15 lbs. for a 1000 lbs. horse). This is assuming no pasture access. Reassess body weight monthly using the clinic scale or a weight tape. Goal is losing 1-2% of body weight per week.
  • If weight loss is not achieved, gradually reduce to feeding 1.2% of body weight in hay per day (12 lbs. for 1000 lbs. horse).
  • Send hay for analysis to determine non-structural carbohydrate (NSC) levels. Please share this analysis with us to help you calculate NSC and evaluate your hay. Ideal is <10% NSC. See for information on submitting a sample for analysis.
  • For hay with high or unknown NSC levels, soaking hay in water for 1-2 hours prior to feeding can significantly reduce NSC content. If this is not feasible, 15 to 30 min can still be helpful. Be sure not to dump the sugar-filled water in grassy areas accessible to your horse.
  • Triple Crown Safe Starch is a chopped forage fortified with vitamins and minerals with a low NSC (8.7%). This can be used as all or a portion of your horse’s daily forage. It does not need to be soaked. Most Teff Hays are also naturally low in NSC. Grass hays are variable in NSC and should be tested and/or soaked.

Hay & Forage

  • In this area of the country, alfalfa hay is generally high in NSC as well as calorically density and is not ideal for horses, especially for horses needing to lose weight.
  • Use a slow feeder, such as a small hole hay net, or divide forage into frequent, small meals to avoid prolonged fasting

Medications and Supplements

  • Thyro-L (Levothyroxine) – While horses with EMS do not have hypothyroidism, short term use of a daily thyroid supplement (<6 months) can be helpful to jumpstart metabolism, encourage weight loss, and improve insulin sensitivity. This medication CANNOT be suddenly discontinued.
  • Metformin – This medication can be given twice a day. It helps decrease sugar absorption and reduces the insulin spike after a meal. It is ideally given 30 minutes prior to feeding, but it can be given with feed too.
  • InsulinWise Supplement – Some research supports use of this daily supplement in improving insulin regulation.

Other Care and Monitoring

  • Watch for signs of laminitis including tender feet on a divergent hoof rings, hard surface/gravel, lameness at the walk (especially in a tight circle/turn), not wanting to walk forward, weight shifting between legs, rocking back on hind feet, parking out, or laying down more frequently.
  • Routine hoof trimming and care is very important in management/prevention of laminitis. Hooves should be picked out daily and any signs of thrush, white line disease, or other hoof abnormalities should addressed promptly.
  • Regular exercise is recommended to accelerate weight loss and improve insulin sensitivity unless laminitis is present.

We'd Love To Hear From You.

Sound Equine Veterinary Hospital does accept new patients. Our tight-knit veterinary team works together and with our clients to achieve the best possible outcomes for the animals you love.

Contact Us

(360) 779-5557 Contact