Oxytetracycline, also known by the names Terramycin® or Liquamycin®, is an antibiotic that inhibits bacteria by suppressing protein synthesis and growth in dogs and cats. Oxytetracycline belongs to a general class of drugs known as tetracyclines. Other related drugs in this class include doxycycline, tetracycline and minocycline. Oxytetracycline is effective against a wide range of bacteria as well as one-celled (protozoa) organisms. It is effective against bacteria that infect the eyes, oral cavity, bone, respiratory tract, sinuses and blood cells. Oxytetracycline is a prescription drug and can only be obtained from a veterinarian or by prescription from a veterinarian. This drug is not approved for use in animals other than livestock by the Food and Drug Administration but it is prescribed legally by veterinarians as an extra-label drug.