EN
The aim of the studies was the evaluation of relationship between the tetracycline residue levels in milk of cows treated intrauterinary with different doses of tetracycline and clinical form of endometritis. Six cows were treated by intrauterine route with pessaries containing tetracycline hydrochloride. The cows in group 1 (n = 3) were affected with acute endometritis, and the cows in group 2 (n = 3) by chronic endometritis. The animals were treated with Tetramykoin supp. uter. ad us. vet. (Léčiva, Praha, Czech Republic) at a dosage of 3g/cow (group 1), and 2g/cow (group 2). Milk samples were collected before treatment and at 12-h intervals for 144 h. The samples were analysed by the high-performance liquid chromatography method with solid phase extraction. The mean concentrations of tetracycline in milk 12 h after treatment were 227.7 μg.1⁻¹ in both groups. The tetracycline residues reached their maximum mean concentrations 24 h after the treatment (276.4 μg.1⁻¹, and 369.6 μg.1⁻¹, for group 1 and 2 resp.). Residues of 13.7 μg.1⁻¹ were detected in group 2 at 108 h. At 120 h the mean concentrations were 33.1μ g.1⁻¹ for group 1 and zero for group 2. No residues were detected after 144 h.