Horses Prone to EMS and PPID

Horses Prone to Equine Metabolic Syndrome (EMS) and Cushing’s Disease (PPID)

Equine metabolic syndrome (EMS)

Equine metabolic syndrome (EMS) has become more and more prevalent in our equine community. It is most often found in middle-aged horses (ages 8 to 18). EMS is characterized by a combination of three main symptoms:

  • Obesity with regional adiposity in the neck, tail head, and supra-orbit (pouch above the eye)
  • Laminitis, both acute and chronic
  • Insulin resistance (aka insulin dysregulation)

Since not all obese horses have EMS and not all EMS horses are obese, an episode of laminitis is often the first indicator of the syndrome. Upon further testing, insulin dysregulation is revealed. It is the combination of these symptoms that yield the diagnosis of EMS. Some EMS horses go on to develop PPID, but not all.

Pituitary pars intermedia dysfunction (PPID) aka Cushing’s disease

Pituitary pars intermedia dysfunction (PPID) aka Cushing’s disease is commonly found in older horses (18-plus years of age). PPID shares several characteristics with EMS so the two are often confused. Some EMS horses will develop PPID, but not all horses with PPID develop EMS or insulin dysregulation. While PPID and EMS horses have some similar symptoms, such as obesity with regional adiposity, laminitis, and insulin dysregulation, PPID is most easily differentiated by the presence of additional symptoms, such as:

  • Abnormal sweating
  • Delayed shedding
  • Hypertrichosis (long, curly hair)
  • Increased drinking and urination
  • Infertility
  • Lethargy
  • Neurological deficits, including blindness
  • Recurrent infections
  • Skeletal muscle atrophy

Supportive Management Practices

For optimal results, supportive management practices should be combined with medication and supplement therapy.

Dietary adjustments

In overweight horses the total calorie intake should be adjusted to encourage weight loss and then maintenance of a healthy weight. Limit sugar and starch (nonstructural carbohydrates) intake. Restrict access to pasture grass.

In hard keepers or horses that are still competing maintenance of a healthy weight is critical. Much needed calories should be derived from high fat and fiber concentrates. Limit sugar and starch intake. Feed alfalfa with caution, as excess protein can cause issues in some metabolically challenged horses. Monitor weight closely and adjust calories accordingly. Don’t allow a horse to become overweight.

For all EMS or PPID horses:

  • Pasture should be eliminated or severely restricted by using a grazing muzzle. Pasture is particularly dangerous in the spring and the fall in areas where cool-season grasses flourish.
  • Avoid high starch and sugar feeds and treats. Choose feeds with a nonstructural carbohydrate (NSC) level of 10% or less.
  • Limit dietary NSC in forage to 12% or less. 10% is optimal, particularly in horses with a past history of laminitis. There are several specialized hay chaff or hay cube products on the market that meet this criterion. Long hay should be tested before fed to determine NSC levels.
  • Soak hay that is above 10% NSC to reduce sugar content. Completely submerge hay for 60 minutes in cold water, or 30 minutes in hot water. Drain well before feeding.
  • In overweight horses, to encourage weight loss, slowly reduce forage intake from 1.5% to 1.25% of ideal body weight over 30 days. Do not feed less than 1% of ideal body weight. Once ideal weight is attained, increase level fed to 1.5% to 2% of ideal body weight. Sudden feed restrictions should be avoided.
  • If additional calories are needed once optimal forage intake is achieved, supply fortifi­ed concentrates that are 10% or less NSC.
  • Adequate exercise is important. Physical exercise has been shown to reduce insulin resistance by assisting in weight management. Horses that are sound should be exercised on a routine basis. Caution must be used with laminitis horses; exercise should be restricted until the horse is sound and then introduced slowly to protect damaged laminae.

If you think your horse is challenged by EMS or PPID, seek the advice of your veterinarian. He or she will help you chart the best treatment and management plan for your horse’s individual circumstances.