A study was conducted to determine whether 1 intramuscular injection of an experimental long-acting oxytetracycline formulation was effective in treatment of induced acute anaplasmosis in cattle and to compare this with the drug response resulting from repeated treatments with an existing, approved oxytetracycline product. The new formulation was supplied in solutions of 200 mg of oxytetracycline/ml and was administered 1 time at the rate of 20 mg/kg of body weight. The experimental formulation was compared with a product providing 50 mg of oxytetracycline/ml which was administered on 2 consecutive days at the dose rate of 10 mg/kg for each treatment. The response to treatment observed in the study animals indicates that 1 injection of the experimental formulation was equivalent to 2 daily injections of the 50 mg/ml product in treating animals with acute bovine anaplasmosis compared with infected nonmedicated control animals. The need for new chemotherapeutic compounds such as this formulation for use in the treatment and control of anaplasmosis is discussed.