I have 3 brooders in my garage. One has 2 week old chicks, one has 4 weeks old chicks & the other has 5 & 6 week old chicks. Friday night I heard a chick sneeze in the 2 week old brooder cage, by Sat. morning I had a couple more sneezing. Now there are a couple sneezing in each brooder. They are still eating and drinking and running around just like normal, just sneezing. I started them on Duramycin in their water first thing Sat. morning. My question is should I switch them to Tylan powder in their water instead. Which one is better at getting rid of respiratory problems in chicks ? I feel so guilty that this has happened, I got 3 chicks from a local breeder and put them in the brooder with my 2 week old chicks. I now know that she had some chicks sneezing before she let me have the chicks. I will never put new chicks in with my babies again