 This study investigated the effects of two xenobiotics, quaternium-15, a preservative used in personal care products, and thiocliprid, a neonicotinoid pesticide, on the hematological profile and erythrocyte osmotic fragility, EOF, of equine and bovine blood samples. Exposure to these xenobiotics caused decreases in red blood cell count, white blood cell count, hematocrit, hemoglobin, mean corpuscular volume, and platelet count, as well as increases in EOF. These findings suggest that exposure to these xenobiotics may cause damage to the blood cells of horses and cows, potentially leading to health problems. This article was authored by Federica Orrigo, Francesca Arfuso, Federica Impolitary, and others.