Endocrinopathic Laminitis: An Incomplete Picture

Photo: Erica Larson, News Editor

Endocrinopathic laminitis--that which stems from hormonal conditions such as equine metabolic syndrome (EMS) or equine Cushing's disease--is detected commonly in equine practice, but it continues to puzzle veterinarians and researchers alike. Ray Geor, BVSc, PhD, Dipl. ACVIM, professor and chair of large animal clinical sciences at Michigan State University's College of Veterinary Medicine, spoke about "metabolic foot" topics he believes require more research at the 6th International Equine Conference on Laminitis and Diseases of the Foot, held Oct. 28-31 in West Palm Beach, Fla.

It's known that horses with endocrine disorders have an increased susceptibility for developing laminitis, and the whys and hows of this susceptibility are the subject of current research efforts by several groups around the world. Take EMS, for example: Over the past six or seven years researchers have made several breakthroughs in determining criteria related to this disease that are associated with laminitis risk, such as higher body condition score, higher serum triglyceride levels (fats), greater insulin response, and lower insulin sensitivity. However, Geor noted some significant knowledge gaps, including needs for:

  • Better-defined characteristics (e.g., breed, age, activity level, diet) linked to endocrine-metabolic phenotypes (physical traits) associated with laminitis;
  • Improved diagnostic approaches for identifying animals at risk for developing laminitis;
  • An understanding of the mechanisms of insulin resistance and abnormal insulin response in these animals; and
  • An understanding of the mechanisms of laminar damage in these animals (i.e. why does laminitis, the failure of the laminae that affix the hoof wall to the coffin bone, occur?).

Geor noted that the importance of obesity and regional fat accumulation in laminitis development in horses is hazy. After all, he pointed out, "Not all fat horses are insulin resistant and laminitis-prone, and some insulin-resistant, laminitis-prone animals are not fat." One hypothesis is that obesity might be tied to a pro-inflammatory state that could lead to laminitis, although recent work in this area suggests that high blood insulin concentrations rather than inflammation are key to the development of laminitis in EMS-affected horses.

Identifying horses and ponies at risk for developing laminitis is a key area for research, said Geor, because "more sensitive and specific diagnostic methods would facilitate early implementation of preventive measures so that laminitis can be avoided."

Ultimately, Geor said, researchers are making exciting progress in the endocrinopathic laminitis picture, but it is still incomplete. An ongoing study involving researchers from the University of Minnesota, Michigan State University, and Tufts University promises to yield important new findings regarding EMS (see www.cvm.umn.edu/equinegenetics/ems/home.html for more information or to participate in this research project). In the meantime owners of horses with any metabolic or endocrine disorders should work with their veterinarians to monitor their horses' laminitis risk.

About the Author

Alexandra Beckstett, The Horse Managing Editor

Alexandra Beckstett, Managing Editor of The Horse and a native of Houston, Texas, is a lifelong horse owner who has shown successfully on the national hunter/jumper circuit and dabbled in hunter breeding. After graduating from Duke University, she joined Blood-Horse Publications as Assistant Editor of its book division, Eclipse Press, before joining The Horse.

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