Over the past three years, veterinarians have increased prescriptions of the SGLT2 inhibitors as they have been proven to be effective drugs for treating acute laminitis, a life-threatening condition in horses. These medications are used in horses who are actively experiencing or are at risk for developing laminitis due to insulin dysregulation or equine metabolic syndrome. As these medications are used more frequently, we are seeing positives show up more often during drug tests.
In humans, SGLT2 inhibitors are used to treat Type 2 diabetes. Sodium-glucose cotransport protein 2, or SGLT2, is a protein in the kidneys. SGLT2 inhibitors work by blocking the protein, therefore preventing the kidneys from reabsorbing glucose and sodium. Instead of returning to the bloodstream, glucose exits the body through urine. In part due to lowering blood sugar, these medications have an insulin-lowering effect, though the precise mechanism of action has not been identified, said Dr. Erin McConachie Beasley, an internal medicine specialist at Grand Prix Equine.
There are no FDA-approved SGLT2 inhibitors for use in horses, though studies have shown that SGLT2 inhibitors, such as the commonly used ertugliflozin, are primarily used as medical therapy in two types of horses:
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Horses with active endocrinopathic or hyperinsulinemic-associated laminitis
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Horses with severe insulin dysregulation or equine metabolic syndrome due to hyperinsulinemia (excess insulin) that can’t be adequately controlled through diet and exercise changes
These medications are not intended to replace strict compliance with dietary and lifestyle management changes the veterinarian prescribes.
“The goal is that these are used as short-term medications during an acute laminitic episode or a severe at-risk period,” said Dr. Beasley. “There are a few cases where the horse needs to stay on the medication in addition to all the veterinary recommended management changes, but that would be the exception, not the rule. The hope is that the horse would return to a normal or less risky metabolic state and come off the medication.”
If your horse is on an SGLT2 inhibitor, know that he will likely drink and urinate more frequently due to its diuretic effect. Therefore, it’s important to make sure he has free access to fresh, clean water and sugar-free electrolytes, especially during periods of high heat and humidity. (Read more about electrolytes.)
SGLT2 inhibitors are prohibited substances at USEF-licensed competitions. However, they are subject to conditions of GR411 Conditions For Therapeutic Administrations of Prohibited Substances. These conditions include the medication must be prescribed by a veterinarian, a 24-hour withdrawal must be observed following the last administration until the time of competing, and a Medication Report Form must be filed appropriately.
If a horse does not have a medical need for SGLT2 inhibitors, these medications have the potential to negatively affect metabolism causing weight loss, increasing the risk for a hypoglycemic (low blood sugar) episode, and inducing hyperlipidemia. Hyperlipidemia is a rise in blood triglycerides (a type of fat) that can result in serious liver problems if the horse stops eating or has concurrent liver dysfunction.
If you have any questions about using SGLT2 inhibitors or other drugs and medications in competition horses, email [email protected]