Antibiotics are used worldwide to control bacterial infection and promote healthy farm animals for milk production. Tetracyclines (TCs) are broad-spectrum antibiotics, widely used in animal husbandry.

In cattle, tetracyclines are used when treating general, respiratory, urinary, and local infections and frequent milk contamination is intramammary administration.

Milk tetracyclines contents reach 50-60% concentrations of those in blood plasma. To prevent any harmful health effects such as permanent stained teeth, hepatoxicity, hypersensitivity reactions on consumers, WHO and EU established the MRL for veterinary drugs.