Oxytetracycline HCL powder belongs to the tetracyclines class of drugs. The medication is effective against a wide range of bacteria including those infecting the eyes, bones, sinuses, respiratory tract and blood cells. It works by interfering with the production of proteins that the bacteria need to multiply and divide, thus hampering the spread of the infection. Besides being used for preventing bacterial growth in cats and dogs, Oxytetracycline HCl is effective for the treatment of bacterial enteritis and bacterial pneumonia in pigs, cows, sheep, chicken, turkey, and even honey bees.