Tissue Distribution and Residues of Antibiotics in Normal and Emergency - Slaughtered Dairy Cows After Intramammary...

Following intramammary infusion of normal cows with a single dry cow and four lactating-cow antibiotic formulations containing penicillin G, neomycin, dihydro-streptomycin, lincomycin and framycetin, low concentrations of drug residues were detected in the kidney, urine, and for some drugs, also in blood and the liver, during the first 24 h after treatment. Drug residues were not detected in meat. In emergency-slaughtered mastitic cows, drug levels were considerably higher and persisted for a longer period than in normal cows. Persistence of drug residues is discussed in terms of the rate and extent of drug absorption from the udder, differences between normal and diseased cows, and effect of dosage form.