Endocrinology

A Cheaper Alternative for Metabolic Care?

By Adam Marcus

Here’s a good reason to let the cat back in the barn—or stable, anyway.

A new study suggests a feline formulation of the drug bexagliflozin can effectively regulate insulin in equids with minimal side effects.

Bexagliflozin belongs to a family of drugs called sodium-glucose cotransporter 2 (SGLT2) inhibitors, which promote the excretion of glucose in the urine, and which equine veterinarians—and physicians—use to control insulin in their patients. However, these agents can be expensive, prompting some clinicians to look for cheaper alternatives.

Caitrin Lowndes, MVB, a research fellow in the endocrinology laboratory at the University of Pennsylvania’s New Bolton Center, said she and her colleagues were inspired to conduct the new study after seeing an increase in the number of veterinarians treating horses with bexagliflozin, which has been approved for use in cats but not horses.

According to Dr. Lowndes, the drug costs about half as much to use as other SGLT2 inhibitors—$4 to $5 per day for a 1,000-pound animal versus $8 to $10 per day for compounded ertugliflozin—making it a compelling, if off-label, option.

Ertugliflozin is a human medication. No insulin-regulating drugs are currently labelled for equine use, and the FDA has approved only a few products for use in veterinary species, she said. However, ertugliflozin is used off-label to treat insulin dysregulation and related conditions in horses and ponies.

“We do some outside testing as a fully functioning endocrine laboratory, and we’d heard some vets were using this formulation as a more cost-effective alternative to other SGLT2 inhibitors,” said Dr. Lowndes, who presented the findings at the 2025 ACVIM Forum, held in Louisville, Ky.

Assessing Efficacy
To assess the effectiveness of the medication, Dr. Lowndes and her colleagues conducted a randomized, placebo-controlled crossover trial in 10 Arabian horses (age range, 5-18 years) with a diagnosis of naturally occurring insulin dysregulation that was not caused by treatment for another condition.

In the first phase, which lasted 10 days, half of the animals received placebo and half received bexagliflozin 15 mg once per day. After a 4-day washout period, the animals switched arms and were again observed for 10 days, followed by another washout period of 12 days. In the final phase, 8 of the horses received bexagliflozin 30 mg for 7 days.

“We based the initial dose on what people were using clinically,” Dr. Lowndes said. To monitor the effects of the drug, the researchers performed an oral sugar test using 0.15 mL/kg of corn syrup at the beginning and end of each treatment phase. They also measured insulin concentrations at rest and after the oral sugar test, as well as levels of triglycerides before and after treatment.

Treatment with the SGLT2 inhibitor was linked to a mean reduction in resting insulin of 15
µIU/mL for the 15-mg dose and 21 µIU/mL for the 30 mg dose, the researchers found. Resting insulin was unchanged for animals receiving placebo.

Insulin levels following a glucose tolerance test fell by 30 µIU/mL and 46 µIU/mL for the small and large doses, respectively, and similar changes were observed for insulin area under the curve. Concentrations of serum triglycerides at rest increased with both the 15-mg and 30-mg doses of bexagliflozin versus placebo. Still, this effect did not appear to be associated with short-term harm, Dr. Lowndes said. “These increases were also lower than those reported with other SGLT-2 inhibitors,” she added.

Long-Term Safety Data Needed
The new study and research on other formulations of SGLT2 inhibitors in horses demonstrated effectiveness with no major signals of harm, Dr. Lowndes said. However, she noted, the long-term safety of the agents in equids is not well understood, as the studies typically have a follow-up period of about 45 days. At least 1 group has reported elevations in certain liver enzymes in animals taking the medications, although whether the drugs caused the issue is unclear, she noted.

“I think it is fair to say in this study, bexagliflozin performed similarly to results reported in other studies investigating SGLT-2 inhibitors, and maybe was more effective than metformin or pioglitazone for treatment of insulin dysregulation, but further comparison studies are needed,” Dr. Lowndes said.
Despite the range of medical options for controlling insulin, Dr. Lowndes said drugs should be the last option, not the first. “Our advice is these are basically rescue drugs for horses that are experiencing laminitis or that are severely hyperinsulinemic,” she said.

“You should not replace diet and exercise” as the front-line approach, particularly in overweight or obese animals, she added. MeV