Determination of fluoroquinolone antibiotic residues in the plasma of Eurasian griffon vultures (Gyps fulvus) in Spain.

Due to the possible toxicological impact, the accumulation of pharmaceuticals in wildlife as a consequence of human practices is of growing concern. The consumption of carrion at feeding stations - the so-called 'vulture restaurants' - with no management of the veterinary drugs it contains may expose scavengers to pharmaceuticals. To demonstrate this, we analyzed plasma from Eurasian griffon vultures (Gyps fulvus) originating from two different areas of Spain for antibiotics such as enrofloxacin and ciprofloxacin, its primary metabolite. Quinolone residues were detected in about 65% (n=106) of birds, of which 15.1% (16/106) had quantifiable amounts of enrofloxacin (0.049±0.102μg/mL) and 5.7% (6/106) of ciprofloxacin (0.009±0.007μg/mL). The differences in exposure between the two sampled areas are attributable to different types of carrion management: the vultures that fed in areas with a high density of dead livestock (supplied directly to feeding stations) were more prone to exposure than those that sought food in areas where carcass availability is more unpredictable. Our findings are evidence that vultures have access to medicated livestock and that there are quantifiable levels of livestock antibiotics in vulture plasma. However, the vultures analyzed in this study had maximum antibiotic concentrations of only 0.4μg/mL, much less than the concentrations used in the clinical treatment of scavengers and a level that is probably too small to cause intoxication.