Equisul-SDT® (Sulfadiazine Trimethoprim) Oral suspension is proven effective for the treatment of lower respiratory tract infections caused by susceptible strains of Streptococcus equi subsp. zooepidemicus in controlled field trials. Contains 400 mg combined active ingredient (333 mg sulfadiazine and 67 mg of trimethoprim). 400 mg/mL.