Although yogurt has probiotics in it this one is supposed to be very good http://www.amazon.com/Vet-Plus-Prob...e=UTF8&qid=1384656333&sr=8-1&keywords=probios and there are many probitoic capsules that can also be used. Tetracycline can be used for up to 14 days, but you should be able to tell if it is working by 1 week. If it isn't doing the job, maybe try Tylan, clortetracycline, oxytetracycline, or Gallimycin.