Publication Date


Degree Program

Department of Agriculture

Degree Type

Master of Science


A recent study has reported that blood glucose levels and founder in horses consuming forage/concentrate mixed diets are positively correlated (Pass et al., 1998). Other studies have reported body fat and insulin resistance are also positively correlated in horses and humans (Hoffman et al., 2003; Boshell et al., 1968; DeFonzo et al, 1991; Kahn et al., 2000). Few studies have monitored these relationships in horses consuming forage only diets, even though the incidence of grass founder is quite high in obese horses and ponies Four thin, four moderate, and four obese horses were grouped two mares and two geldings per group in a completely randomized design. They were allowed six months to adapt to an all forage diet consisting of free choice access to a mixed grass pasture. The pasture consisted of primarily Fescue with limited additional quantities of Bermuda Grass and Blue Grass. Following the adaptation period, blood samples were collected at four hour intervals, during a twelve-hour grazing period to determine effects of body condition, sex, and time of sampling on blood insulin and glucose concentration. Blood glucose analysis was done utilizing the Ultrasmart monitor. Accuracy verification was obtained by dual sample analysis with the Vetest 8008 animal glucose monitor. Results indicate the Ultrasmart monitor is a highly accurate and effective method of analyzing blood glucose concentrations in the horse. No significant blood glucose variation due to time of sampling, sex, or body condition was observed. Sex of animal and time of sampling had no significant effect on circulating insulin concentration. Mean blood glucose concentration for all horses consuming the pasture diet was 77 mg/dl. Results also indicated that the mean normal blood glucose concentration of horses consuming this grass pasture diet was similar to the mean of 74.7mg/dl reported for horses consuming forage/concentrate mixed diets (Williams et al., 2001). Blood insulin concentrations of the moderate horses were not different from those of the thin or fat horses. They were however significantly lower, in the thin horses than the obese horses. Therefore, fatter horses secreted greater quantities of insulin while maintaining normal blood glucose levels. In a second study, Glycosylated Hemoglobin (HBAlc) measurements of the aforementioned horses using a human blood meter was attempted. The technique was not effective for measuring horse blood and was abandoned. Further research in this area may provide an effective mechanism for evaluating long term blood glucose and insulin chemistry.


Agriculture | Animal Sciences