Small units of genetic material called microRNAs (miRNAs) collected from a horse’s blood sample might help veterinarians diagnose equine metabolic syndrome (EMS). This finding benefits horses, owners, and veterinarians because EMS left untreated, or undiagnosed can put horses at risk for life-threatening and painful laminitis.

miRNAs are already widely used in human medicine to help diagnose various types of cancer, neurodegenerative disorders, autoimmune diseases, and endocrine conditions such as diabetes and metabolic syndrome. Using the knowledge and technology already established in the human metabolic syndrome arena as a launching pad, Spanish researchers hoped to determine if miRNAs were equally useful in EMS diagnosis.

A Spanish research team led by Elisa Mª Espinosa-López, PhD, and Guadalupe Gómez-Baena, PhD, both of the Universidad de Córdoba, collected blood samples from three groups of horses: (1) healthy nonoverweight/obese horses; (2) healthy overweight/obese horses, and (3) horses diagnosed with EMS. They isolated the miRNAs from the samples and compared them across the three groups. In total, 45 horses were included in the study, primarily Andalusian horses with a mean age of 12.91 years. As expected, basal (resting) insulin levels were significantly higher in the EMS group at 44.24 milliunits per liter (mU/L) compared with an average of 11.84 mU/L in the overweight/obese horses without EMS and 11.93 mU/L in the healthy nonoverweight/obese horses.

The researchers identified significant differences in the expression levels of four miRNAs: miR-15a, miR-186, miR-132, and miR-221. Specifically, levels of miR-221 were significantly higher in the EMS group compared to the healthy group, and miR-132 was significantly higher in overweight/obese horses compared to both healthy and EMS horses. Both miR-15a and miR-186 were significantly higher in healthy horses compared to the EMS and overweight/obese groups.

Espinosa-López and Gómez-Baena analyzed this information to better understand the practical roles of these four miRNAs. “Functionally, the target genes associated with these miRNAs include FOXO1, SIRT1, and TWIST1.”

In the paper, the researchers explained that, based on studies in humans, FOXO1 is involved in inflammation and oxidative stress and plays an important role in the regulation of insulin signaling and glycemic homeostasis (the body’s maintenance of blood sugar levels). SIRT1 appears to play a role in insulin resistance and diabetes, while TWIST1 appears to be involved in insulin resistance.

Future Research Directions

“Further research in this field will explore a broader panel of circulating miRNAs in larger cohorts (groups) of horses and will be directed to elucidate (explain) the mechanisms supporting the association between the identified miRNAs and FOXO1, SIRT1, and TWIST1 genes,” said Espinosa-López and Gómez-Baena.

Currently, the research team is developing a novel panel of candidate miRNAs to help diagnose EMS in horses. Espinosa-López and Gómez-Baena said they are also studying how the disease develops and worsens, including how tiny particles released by cells, known as extracellular vesicles, might contribute to its progression.

The study, “Circulating microRNAs as potential predictive biomarkers of equine metabolic syndrome,” was published in The Veterinary Journal in August 2026.