No stopped the corid after the 5 day treatment and used the safeguard 3 days because I was confused read 1 day and then read use it for 3 so to be safe I used it for 3. But why up to day 7 did they sound good and then some sound bad again.
I had them confined in the coop for that length of time. The wind dos blow for the last two days stirring up dust could that of done it!? I am about ready to give up! Can you mix the Tylan injectable with water I suppose we need to start over here.
Did the chickens start out with Respiratory Illness, Coccidiosis, or worms?
The Duramycin you treated for 7days? It looks like your dosage was incorrect (you used 1 Tablespoon). Use
5 Teaspoons per Gallon of drinking water. Make sure this is the only water they drink. Try this before you try the Tylan50 since you did see improvement with the Duramycin.
I understand why you kept them isolated in the coop, but they do need fresh air, so if you have a place where they can get some air and sunshine that may be helpful as well.
Don't give up, you are doing the best you can
It is possible they may get sick again, or if you add new birds to your flock in the future that the illness could be contracted. But that is in the future. It sounds like most of them have cleared up and are doing well for the moment, so treat the ones that are still sick.
Hopefully increasing your dosage will work for you. If not, then you can try the Tylan50.
Just my thoughts.
