It is preferable to not knowing what they had in the first place. And what you need to do to the housing or even if you can ever keep birds on the property again....I read that once you send your chicken to lab and get information back it's often too late but I will give them a call today and see what they say.
The problem with medicating before one knows what is afflicting the birds is that if a necropsy follows, the results can be rendered inconclusive by the meds.Well I finished 5 day injections with Tylon and decided to start tetra in their drinking water. Only 3 have respiratory symptoms at this point and they are quarantined, the others are just lethargic and stand around like zombies....
A surprisingly small percentage of things that could be wrong can be cured with antibiotics.