Welcome to BYC. I am sorry to hear about your chickens. How did you give the injections? Tylan50 is normally injected into the breast muscle 1/4 inch. Many people give Tylan injectable ORALLY to prevent problems. How are the chickens doing at this time?
I injected in the back of her back. In between where her wings meet..her symptons immediately got worst..matter of fact it seems her weezing was gone until I gave the antibiotic shot. And right now I can still here the weezing just not as bad