Equine metabolic syndrome is a challenging condition for both veterinarians and horse owners to deal with, especially for horses with insulin dysregulation (ID). In a recent study, researchers from Denmark considered previous findings that point toward the role of intestinal microbiota in gastrointestinal barrier protection against leaky gut syndrome and metabolic disease. They evaluated the benefits of dietary supplementation with oligosaccharides and how it could mitigate insulin dysregulation.
Crossover Study Evaluating Oligosaccharide Supplementation
The crossover study involved 15 horses aged 3-19 years enrolled in two feed supplementation periods between September and January. All horses had a body condition score of ≥ 5 (Henneke scale), with most having a BCS of 6-8 and all but one having a cresty neck. Two horses had previously been diagnosed with pituitary pars intermedia dysfunction (PPID), five horses had previous laminitis, and one horse had polysaccharide storage myopathy (PSSM).
Prior to the study, it was noted that five horses had received oral metformin hydrochloride (MH), which indirectly decreases enteric glucose absorption. An increase in some intestinal bacteria is a response to MH; these beneficial bacteria increase production of short-chain fatty acids with anti-inflammatory properties. Oral bioavailability of MH in horses is poor at less than 7%. MH was discontinued for the duration of the study.
All horses in the study were fed the same volume and type of feed and had similar housing and paddock access. The horses received either oligosaccharide supplementation (OS) or calcium carbonate once daily. The research team measured plasma insulin, endotoxin, serum amyloid A, and blood glucose concentrations using an oral sugar test (OST) both before and after each supplementation period. They also evaluated fecal samples for microbial communities. The washout period between trials lasted 14 days, then each horse received the other supplement.
At the beginning of the study, 10 of 15 horses had plasma insulin concentrations > 60 mIU/L. Geldings had higher glucose measurements than mares; plasma concentrations of insulin were equivocal between mares and geldings. The results at the end of the study showed:
- A significant reduction in insulin concentrations in geldings fed the OS.
- No significant change in insulin in mares fed the OS.
- No significant changes to the gut microbiota of mares fed OS.
- Horses with insulin concentrations > 60 mIU/L had greater microbial diversity compared to those with insulin < 60 mIU/L. This could in part be due to previous MH treatment or related to intestinal microbial effects of low-sugar diets fed to overweight horses with previous laminitis.
- Intestinal bacterial community composition differed significantly between horses with previous laminitis compared to those without. Horses with laminitis had significantly greater beta diversity.
- There were no significant effects on SAA or endotoxin concentrations in any of the horses.
Final Thoughts on Oligosaccharide Supplementation for Metabolic Horses
The authors suggested that oligosaccharide supplementation might be a means to elicit noninvasive, improved effects in horses with insulin dysfunction and equine metabolic syndrome.
von Münchow A, Torp Yttergren S, Jakobsen RR, Luthersson N, Hansen AK and Lindenberg F. Oligosaccharide feed supplementation reduces plasma insulin in geldings with Equine Metabolic Syndrome. Frontiers in Microbiomes 2023, vol. 2:1194705. doi: 10.3389/frmbi.2023.1194705