Tylan 200 is 200mg per ml, while Tylan 50 is 50 mg per ml. 50mg per 5 pounds is about standard, given orally twice a day, for 3-5 days. I would use 1/4 ml of the Tylan 200, and I would give it for 5 days. There is no need to alternate with Terramycin (oxytetracycline.) They both treat the same...