Excretion of intra-uterine applied oxytetracycline and lugol in cows milk

Sixteen dairy cows with chronic puerperal endometritis between 3 and 8 weeks post partum were treated with intra-uterine applied oxytetracycline (OTC) and lugol. OTC was rapidly removed from plasma and was not detectable after 48 hours. The concentration of OTC in milk did not exceed 40 mu g/kg, and it was still detectable in milk 34 hours after treatment. The concentration of OTC in milk was always lower than the limit of 50 mu g/kg used by milk-testing stations and the European limit (MRL) of 100 mu g/kg. Milk from cows treated with lugol did nor cause inhibition in the plate test.