Preparation of a new formulation of oxytetracycline 20% injectable solution was done for veterinary therapeutic use. Information about all the materials used in preparation of formula were collected from the well known pharmacopeia while analar material were provided and used to prepare about three pilot formulae, from which the final one was prepared. Stability of new formula was tested in different room environmental conditions by comparing any change in physicochemical properties concerning form, colour, transparency, pH in different storage room temperatures for 18 months as well their MIC value and bacterial inhibition rate formorethan 12 months. The results showed that the new drug proved its stability, antibacterial activity when tested both in vitro against E coli 0.78 was growth in which MIC was 0.2 µg /ml. It was also tested clinically in therapy of group of infected sheep and cows (4 each) with respiratory diseases, at the college of veterinary medicine, University of Baghdad as well as in the central veterinary hospital in comparison with other similarly infected group treated with common commercially used 20% oxytetracycline drug (Alamycin)® while control group treated with normal saline. The results showed improvement of the animals of both treated groups when compared with control one, which its animal health deteriorated and improved when treated with the formula. Both quantitative and qualitative results for oxytetracycline 20% formula as well as its physicochemical properties and steritity was tested by Board of drug and biological standardization, Iraqi Veterinary State Company (I.V, S.C.) and a certificate of approval of quality, quantity, antibacterial activity was issued by I.V.S.C. for new oxytetracycline 20% injectable solution and registered, it as new drug formulated by the College of Veterinary Medicine, university of Baghdad for veterinary use.