This study hypothesized that back fat thickness and some adipokines could serve as markers of obesity in mares via investigating the association of hyperinsulinemia and overweight, laminitis, with circulating insulin, insulin-like growth factor-I (IGF-1), catalase, glutathione reduced (GSH), nitric oxide (NO), total cholesterol, glucose, total proteins, albumin, globulins, and lactate dehydrogenase (LDH). The gene discussed is CAT; the disease is hyperinsulinism.