Obese and insulin-resistant horses may benefit from the addition of psyllium to their diet.
Made from the husk of seeds of the shrub-like herb called Plantago ovata, psyllium is a high-fiber dietary additive commonly fed to horses to help expel sand from the digestive system. Intrigued by studies that found psyllium lowered blood glucose in people, researchers at Montana State University set out to see if it could do the same for horses.
For the study, the Montana State team selected 16 horses of normal weight who had no metabolic conditions. In a two-month trial, the horses each day received their daily hay and grain ration, along with either 90 grams, 180 grams or 270 grams of a psyllium or an inert supplement to serve as a control. On the final day of the study, each horse underwent a series of blood tests to determine his blood glucose and insulin responses immediately after meals.
The data showed that horses who received a psyllium supplement, regardless of dose, had lower blood glucose levels after eating. In addition, horses on the highest dose of psyllium supplement had lower insulin concentrations after meals, compared to the rest of the horses, indicating greater sensitivity to the hormone.
Exactly how psyllium can help lower blood glucose and insulin isn't clear, says Shannon John Moreaux, DVM, but "the consensus is that psyllium increases bulk in the stomach and small intestine, which in turn alters transit time and enzymatic and microfloral digestion to some degree."
Although the study horses were in good condition, "it is reasonable to expect similar results in obese and metabolically challenged horses," says Moreaux, adding that the drop in glucose seen in the study was significant enough to be beneficial for those horses.
"Any decrease in glucose absorption is significant when it comes to horses with metabolic syndrome, and any change in insulin sensitivity is, too," he says. "While exercise and nutrient control are always the most important treatment/management practice for these horses, we are interested in anything that may assist these obese or metabolically challenged horses, especially those that can't be exercised appropriately, due to laminitis-associated pain, for instance."
Although Moreaux's studies are still ongoing, he says, if you own an obese horse you may want to talk to your veterinarian about adding psyllium to your overall management plan. "I personally feel that we have shown enough benefits---and I have seen enough benefits in horses in my private practice---to continue using psyllium in conjunction with diet management and exercise when possible. It is important to note that psyllium's effect on micronutrient metabolism has not been studied in horses; however, in human studies no significant changes in vitamins and minerals were noted. If horse owners are interested in using psyllium to help manage an obese horse, or a horse with equine metabolic syndrome or insulin resistance, they should consult with their equine veterinarian."
Reference: "Psyllium lowers blood glucose and insulin concentrations in horses," Journal of Equine Veterinary Science, April 2011