Sustain III Cattle Bolus 50ct - Prescription RequiredSustain III Cattle Sulfa Boluses 50 count Sulfamethazine in a sustained release bolus provides treatment level for 3 days in beef and non lactating dairy cattle. Effective against foot rot, shipping fever, calf diphtheria, acute metritis caused by organisms sensitive to sulfamethazine. Dose: One bolus per 200 lbs. *This product requires a prescription from your veterinarian. They can submit it in a few different ways: Fax a prescription form to 515