) Legacy Gentamicin Sulfate Solution is recommended for the control of bacterial infections of the uterus (metritis) in horses and as an aid in improving conception in mares with uterine infections caused by bacteria that are sensitive to gentamicin. Legacy contains 100 mg gentamicin sulfate solution per ml. The recommended dosage is 20-25 ml daily for 3-5 days during estrus. Each dose of Legacy should be diluted with 200-500 ml of sterile saline and infused into the uterus. Gentamicin Sulfate.