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Insulin Resistance in Horses Varies Throughout the Year and Among Breeds
Author(s) -
Moffatt Cheyenne N.,
Paquin Zachary W.,
Guild Ayla,
Johnson Kathryn M.S.
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.719.3
Subject(s) - laminitis , insulin resistance , breed , insulin , horse , medicine , zoology , biology , endocrinology , veterinary medicine , paleontology
In horses, insulin resistance is directly associated with laminitis, a severe lameness condition within the hoof and a leading cause of equine euthanasia. The onset of laminitis is most likely to occur in the early spring, and the risk of the condition is increased in specific horse breeds; however, it is unclear if insulin resistance is the mechanism that induces the seasonal onset of laminitis or increases occurrence in particular breeds. To determine if, 1) seasonal changes in insulin resistance occur as a possible precursor to laminitis; and 2) if insulin resistance is increased in breeds more susceptible to laminitis, horses (n=35) in southern Wisconsin and northern Illinois were classified as belonging to breeds that have an increased risk (Saddlebreds, n=7, and Welsh ponies, n=10), a decreased risk (stock horses, n=11), or an unknown risk (draft/draft crosses, n=7) of laminitis. Jugular vein blood samples were collected from all horses in September, November, January, March, and May. For all samples, plasma glucose and insulin levels were measured and insulin resistance was determined as the ratio of glucose to insulin concentrations (GIR), with lower GIR levels indicative of increased insulin resistance. There was no relationship between the time of year and glucose or insulin levels, but there was a significant seasonal effect on GIR (MANOVA, F(4,28) = 2.86, p=0.04). There was also a significant effect of breed on GIR (MANOVA, F(3,31) = 3.21, p=0.04), with the lowest GIR values attributed to breeds associated with a high risk of laminitis. Therefore, insulin resistance may be a mechanism by which breed and seasonality increase the risk of laminitis in horses. In addition, very little is known about the risks for insulin resistance and laminitis in draft and draft cross horses. Despite their greater stature and weight, often associated with insulin resistance, the draft and draft crosses had the greatest GIR, indicating the least insulin resistance. These findings suggest that despite their greater weight and likelihood of obesity, horses that belong to draft and draft cross breeds may have protective mechanism against insulin resistance, warranting further investigation.