The oral glucose test predicts laminitis risk in ponies fed a diet high in nonstructural carbohydrates.

The research article investigates the correlation between the development of laminitis in ponies and their insulin/glucose levels in response to an oral glucose test and a diet high in nonstructural carbohydrates.

About the Research Study

• The investigation involved 37 ponies, all subjected to an oral glucose test (OGT), in which they consumed 1g of dextrose per kg of body weight in their feed.
• The ponies’ 2-hour serum insulin concentrations ranged from 22 to 1,133 micro international units per milliliter (μIU/mL).
• Following the OGT, the ponies underwent a diet challenge period (DCP), where they consumed 12g of nonstructural carbohydrates (NSCs) per kg of body weight each day, for up to 18 days.

Data Gathering and Results

• On the second day of the DCP, both glucose and insulin responses were measured.
• The team of researchers also monitored the basal adrenocorticotropic hormone (ACTH) levels, as well as any clinical signs of pituitary pars intermedia dysfunction (PPID), a common hormonal disorder in older horses.
• Of all the ponies tested, 14 (38%) developed Obel grade 1 or 2 laminitis.

Significant Findings

• Ponies that developed laminitis had higher maximum concentrations of blood glucose and serum insulin in response to the diet.
• Furthermore, the occurrence of laminitis correlated with the pony’s insulin concentrations during the OGT. Specifically, laminitis occurred in none of the ponies with post-dextrose insulin levels under 50 μIU/mL, in 35% of those with insulin levels between 50 and 195 μIU/mL, and in 86% of ponies with insulin levels above 195 μIU/mL.
• Half of the ponies (8 out of 16) with basal ACTH concentrations above the seasonally accepted reference ranges developed laminitis, including all 5 ponies that exhibited clinical signs of PPID.

Conclusion

• Increased glucose and insulin responses to both the oral glucose test and the high-NSC diet were associated with the development of laminitis.
• This suggests that the likelihood of laminitis can be predicted based on a pony’s insulin and glucose responsiveness to oral carbohydrate challenges. This finding could have substantial implications for preventative care regarding laminitis in ponies.