Distribution of chloramphenicol residues in lactating cows following an external application

The aim of the present investigation was to demonstrate the presence of eventual chloramphenicol residues in blood plasma, urine and milk of dairy cows after topical application of a product, which contains 5% chloramphenicol in an alcohol solution and was commercially used as a spray registered for animals not intended for human consumption. The experiment was performed on two (A + B) Holstein-Frisian cows in the early lactation period. The indication for treatment with the described antibiotic solution was in the first case (cow A) a teat lesion and in the second case (cow B) skin lesions on the shoulders and the claws. Four consecutive dermal administrations inside first 41 h of the experiment were performed for both animals at the same time points. Milk, blood and urine samples were taken immediately before first treatment and in regular intervals inside applications and up to 12 days after the last application. All investigated matrices were analyzed using capillary GC-ECD after chloramphenicol derivatization. The outcome of our study confirmed our hypothesis that illegal and violative treatment (food-producing animals) of wounds with a spray containing chloramphenicol results in considerable residues of the active substance in milk, blood plasma and urine of the injured animals.