Equine Metabolic Syndrome (EMS)
Equine Metabolic syndrome (EMS) or Cushing’s syndrome is a progressive disease that follows a predictable course in accordance with the parameters of the insulin resistance model. Insulin resistance (IR), in both humans and horses, initiates the metabolic syndrome and is considered to be the root of the disease process. IR refers to a breakdown in the cells’ ability to respond normally to insulin action; therefore the term “resistance”. Quantitatively, IR displays a pattern in blood tests that shows normal serum/blood glucose and elevated serum insulin. This pattern is the foundation of all the abnormalities found in the metabolic syndrome.
As IR progresses insulin levels continue to elevate while glucose remains “normal.” Increasing insulin production and secretion by the pancreatic beta cells elevates insulin levels in the blood. The reason that the beta-cells keep secreting more insulin, even though the glucose levels in the blood remain normal, is because they are “picking-up” the greater cellular need for efficient utilization of the glucose; another reflection of a greater resistance to insulin action. Therefore more insulin is needed to “keep” glucose levels in the blood “normal.” As insulin continues to rise the integrity of the cells diminish and the problems for the horse grow more severe.
For approximately a quarter of these horses serum levels of glucose will begin to elevate above the reference range while insulin levels in the blood reach inordinately high concentrations: at this place in the metabolic syndrome progression the horse is now diagnosed as type 2 diabetes. Each progression along the metabolic syndrome course increases the likelihood and damage of an acute laminitic episode as well as the many other associated health problems accompanying this disease process.
As soon as a horse enters the IR phase the risk of laminitis begins and the risk increases as the metabolic syndrome progresses with higher levels of insulin; and during this course less of a trigger is needed to initiate an acute laminitic event. Laminitis is the most “visible” of the constellation of abnormalities that accompany the metabolic syndrome; some of the others, not immediately noticeable, are a decreased immune functioning, vascular issues, a variety of categories of anemia, and gastrointestinal problems. Each of these serious health problems increases as the metabolic syndrome progresses.