Terramycin or Tylan for Chick Congestion

[CharlieBaby]

Update and follow up questions: I bought the Tylan 200 liquid but never used because 1) believe illness was/is infectious bronchitis and not sure if any secondary infections were/are present, 2) worried about doing more harm than good by wiping out bacteria in young chicks, and 3) I didn’t feel confident in my ability to properly dose the Tylan.

Chicks are now 4 weeks old and still sneezing occasionally. My Giant Cochin hasn’t been gaining weight as quickly as the others and recently her poops went from normal (cecal, solids, etc) to watery. The pic is her best poop of today; all others have been 100% watery with no solid matter. As usual, lots of conflicting information online, with some saying to treat and others saying no biggie. Wondering if I should add apple cider vinegar ACV and/or Corid to water for 5 days, or possibly now dose with Tylan. I could also wait and do nothing. I still suspect infectious bronchitis and possibly coccidiosis and/or secondary infection.

To add, she is eating, drinking, and jumping around like normal. She is peeping a lot, but not the “9-1-1 chirp”. Other chicks have normal poops and acting normal minus very occasional sneezing (less sneezing than week ago).