The Impact of Etomidate on Tear Secretion and Oxidative Stress Markers in Domestic Male Cats: A Clinical Study

The aim of the present study was to evaluate the effects of etomidate on tear secretion and tear oxidative stress parameters, including total oxidant status (TOS), total antioxidant capacity (TAC), and Oxidative Stress Index (OSI), in domestic male cats. Thirty client-owned male domestic shorthair cats were enrolled in a prospective controlled clinical study and allocated to either an intervention group receiving etomidate (2 mg/kg intravenously) or a control group that did not receive any anesthetic or sedative drugs. Tear secretion and oxidative stress parameters were assessed at baseline (T0) and at 5 (T1), 10 (T2), and 15 (T3) minutes following etomidate administration in the intervention group and at corresponding observation time points in the control group using the Schirmer tear test. Tear production was significantly reduced in the etomidate-treated group at all postadministration time points compared to baseline (p < 0.001), with a clear time-dependent decrease observed during the first 15 min after administration. In contrast, no significant changes in tear secretion were detected in the control group. Tear oxidative stress analysis revealed a significant increase in TOS and OSI at T2 and T3 compared to baseline (p < 0.001), accompanied by a significant reduction in TAC at the same time points. No significant alterations in oxidative stress markers were observed in control cats. These findings demonstrate that etomidate has a marked suppressive effect on tear secretion and induces oxidative stress in tear fluid shortly after administration. Reduced tear production combined with increased oxidative stress may compromise tear film stability and ocular surface integrity, increasing the risk of dry eye-related complications. Accordingly, the use of etomidate should be carefully considered in patients with preexisting ocular disease, and appropriate ocular protection should be implemented during anesthesia, particularly in cases requiring prolonged immobilization.