Prevention and Management of Equine Metabolic Syndrome

Equine Metabolic Syndrome (EMS) Prevention and Treatment.


Horses with signs of EMS usually need to lose weight.  Hay nets are really valuable tools in promoting weight loss.  You should talk to your vet, of course, but generally horses fed 1.5% of their ideal weight in hay will lose weight.  You may need to adjust that slightly up or down.  To get a feel for how much this is, weigh out multiple flakes of hay.  A 1000# horse getting 15#  (1.5% BW) of hay per day will typically feel that he should have more hay.

  • Use a slow feeder hay net to help your horse eat more slowly, feel more satisfied, and prevent ulcers from low ration intake.
    • Nibble Nets
    • Smart Pak Small Hole Hay nets.
      • These nets can be tied and put low down to promote more normal eating posture vs hanging slow feeders on the wall. You DO need to monitor for entrapped shoes and hooves.


Horses with signs of early metabolic syndrome should all be protected from the dangerous sugars in stressed grasses.  Here in Vermont, where we have mostly C3 grasses that generate fructans, it is important to avoid times of grass stress (spring, fall, drought) and times of the day when the grasses are accumulating fructans (afternoons.)

  • Wait to turn your horse out on the fields until the grass has grown in fully and is thriving and healthy. This will have the added benefit of saving your pastures.
  • When your horse is out, make sure that he has a muzzle on. Try GreenGuard Grazing Muzzle or Best Friend’s Grazing Muzzle.
  • Turn your horse out at night or early mornings.  Avoid afternoons.


Horses with EMS or signs of the disease should also be exercised if possible.  Exercise will greatly help muscles take up sugars after meals and moderate blood sugar.  Exercise can contribute to reversing EMS.

  • Exercise, even at a brisk walk, for 15 minutes 5 days per week.


Horses with signs of EMS should eat a low sugar hay, a ration balancer, and fresh water.  It is great to get your hay tested and send your forage report to your veterinarian for evaluation and to help diet planning.  Unless indicated by your veterinarian, it is best to avoid all grains and processed feeds except a ration balancer which provides necessary vitamins and minerals and proteins.

  • Test your hay if you can.  For “easy keepers” or EMS horses, we want hay that is high in protein, digestible, and low in sugar and starch.
  • Ration balancers:
    • High volume (about 3 cups per 1000# depending on brand)
      • Poulin’s ETec Balancer
      • Blue Seal’s Min-a-Vite
      • Nutrena’s Progressive Nutrition Grass Balancer
    • Low volume (2-4 oz per 1000# depending on brand)


Horses with signs of EMS may need to take a Thyroid supplement during the spring and fall.  Your vet may do this because levothyroxine can help increase blood flow to feed to prevent laminitis and it can help with weight loss.  The effects are short lived.  60-90 days per treatment period.  Many horses benefit from 40-60 days of therapy as the grass comes up and as the grass transitions toward winter if there is no way to keep them off grass entirely during those times.  Some EMS horses are put on Thyro-L to help get the disease under control, also.  This seems to be primarily because of the weight loss that thyroid hormone can provide.


If your horse has been diagnosed with EMS, your vet may use other drugs as well.  Metformin is a popular choice for its ability to regulate insulin levels.