Section 7
Chapter 6,811

Tissue reactions and residues in slaughter cattle after administration of long-acting oxytetracycline formulations

Petzer, I.M.; van Staden, J.J.; Giesecke, W.H.

Journal of the South African Veterinary Association 55(3): 107-111


ISSN/ISBN: 1019-9128
PMID: 6492061
Accession: 006810566

Samples from 40 slaughter cattle were investigated over 10 wk for determining macroscopic tissue reaction following i.m. administration of Liquamycin/LA (Pfizers) into the thigh and Terramycin/LA (Pfizers) G 333 into the neck, respectively. Antibiotic residues in the lesions were assessed under UV light and by microbiological means. Antibiotic residues were still detected after 7 wk in the thigh and 5 wk in the neck. One week old lesions in the thigh consisted mainly of a local necrotic center, up to 120 mm in diameter, with a hemorrhagic/zone and surrounded by edema and petechia in adjacent muscle. This was gradually replaced by mainly fibrotic tissue as the weeks went by and eventually by local abscess formation still apparent 10 wk later. Much the same pattern was seen in the neck but of milder degree and shorter duration, .+-. 6 wk. Alarming is the fact that only in 1 case of 40, a lesion could be detected in the carcass on the slaughter line, the others could have passed fit for human consumption in an abattoir. Because the manufacturer suggests a 28 day withholding period before slaughter and after administration of the product, results of this investigation raise several questions on format, completeness and contents of such directions for use and their implications for meat inspection, meat hygiene and public health.

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