Effect of dietary fructans and dexamethasone administration on the insulin response of ponies predisposed to laminitis.

The study examines the effect of dietary fructans and dexamethasone treatment on blood insulin levels in ponies predisposed to laminitis, a painful hoof condition, in comparison with healthy ponies.

Objective and Methodology

• The objective of the research was to find out if the grazing habit, specifically the intake of fructan carbohydrate found in grass, causes heightened changes in serum insulin concentration in laminitis-prone (LP) ponies compared to healthy ponies. Apart from this, it also aims to examine the insulin responses to the dexamethasone suppression test, a steroid treatment often used to combat inflammation and immune disorders.
• The study was prospective and performed on 10 LP and 11 healthy adult non-obese mixed-breed ponies. Several methods were used including insulin-modified IV glucose tolerance tests. In diet-related trials, ponies were initially exposed to pasture and later switched to a hay diet. In another test, ponies were given a basic hay diet, then supplemented with inulin, a kind of dietary fiber.
• Researchers measured serum insulin and plasma glucose concentrations before and after dietary changes. They also noted serum cortisol and insulin concentrations after the dexamethasone suppression test.

Findings

• The researchers found that the LP ponies were insulin resistant, with median insulin sensitivity lower than that of the control ponies. The median insulin concentration in LP ponies was significantly higher than that in control ponies when grazing.
• The insulin levels of LP ponies decreased after switching to a hay diet, but the same insulin levels significantly increased (5.5-fold) when inulin was added to the hay diet. This indicates that the ingestion of fructan carbohydrate heightened insulin concentration in these ponies.
• LP ponies showed a higher surge in serum insulin concentration 19 hours after the administration of dexamethasone, compared to control ponies.

Conclusion

• The study concluded that non-obese ponies with a predisposition to develop laminitis demonstrated higher insulin resistance, and this was further exposed when these ponies were fed plant fructan carbohydrates or underwent dexamethasone treatment. This research can help in devising dietary plans and medical treatments for preventing or managing laminitis in ponies.