Section 520.2200 - Sulfachlorpyridazine(a)Specifications.(1) Sodium sulfachlorpyridazine powder.(2) Each milliliter (mL) of suspension contains 50 milligrams (mg) of sodium sulfachlorpyridazine.(b)Sponsor. See No. 016592 in § 510.600(c) of this chapter.(c)Related tolerances. See § 556.630 of this chapter.(d)Conditions of use. It is used as follows:(1)Calves - (i)Amount. Administer 30 to 45 mg sulfachlorpyridazine powder per pound (/lb) of body weight per day in milk or milk replacer in divided doses twice daily for 1 to 5 days.(ii)Indications for use. For the treatment of diarrhea caused or complicated by Escherichia coli (colibacillosis).(iii)Limitations. Treated ruminating calves must not be slaughtered for food during treatment or for 7 days after the last treatment. A withdrawal period has not been established for this product in preruminating calves. Do not use in calves to be processed for veal. Federal law restricts this drug to use by or on the order of a licensed veterinarian.(2)Swine -(i)Amount. Administer 20 to 35 mg/lb body weight per day in divided doses twice daily for 1 to 5 days in drinking water or an oral suspension containing 50 mg per mL.(ii)Indications for use. For the treatment of diarrhea caused or complicated by E. coli (colibacillosis).(iii)Limitations. Treated swine must not be slaughtered for food during treatment or for 4 days after the last treatment. Federal law restricts this drug to use by or on the order of a licensed veterinarian. 75 FR 10166 , Mar. 5, 2010, as amended at 79 FR 28829 , May 20, 2014; 81 FR 17607 , Mar. 30, 2016; 81 FR 94990 , Dec. 27, 2016; 88 FR 27699 , May 3, 2023 81 FR 17607, 3/30/2016; 81 FR 94990, 12/27/2016; 88 FR 27699, 5/3/2023