Enrofloxacin induces mild and transient vascular alterations following regional limb perfusion in horses

BACKGROUND: Regional intravenous limb perfusion (RILP) is widely used in equine practice for achieving high local antimicrobial concentrations while minimizing systemic exposure. However, certain drugs, including enrofloxacin, have been associated with vascular irritation and thrombosis, and their thrombogenic potential remains poorly characterized. OBJECTIVES: This study aimed to evaluate the thrombogenic potential of enrofloxacin administered via RILP in the cephalic vein of clinically healthy horses. METHODS: Ten adult horses underwent RILP in both forelimbs: the right limb received 10 % enrofloxacin (1.5 mg/kg) diluted in 0.9 % NaCl to a total volume of 20 mL, while the left limb served as control (0.9 % NaCl, 20 mL). Clinical, thermographic, and ultrasonographic assessments were performed at baseline, immediately after tourniquet removal, and 24 and 48 hours post-RILP. Statistical comparisons were made between treatments and time points (p < 0.05). RESULTS: No alterations in vital parameters were observed. No temperature differences occurred between limbs, although transient bilateral increases were detected immediately after tourniquet removal. Ultrasonography revealed temporary reductions in venous lumen diameter, returning to baseline within 24 hours in both groups. In the treated group, venous wall thickening was detected in six horses, and one developed mild thrombophlebitis. All lessons were resolved within 48 hours. CONCLUSIONS: A single administration of enrofloxacin via RILP in the cephalic vein induced only mild and transient vascular changes, suggesting a low thrombogenic potential in healthy adult horses.