my birds having some respiratory issues now too.I treat with Tylan50. its excellent for respiratory problems. dose is large birds 1/2cc small birds 1/4 cc once daily in the breast muscle for 5 days. do NOT worry that the bottle says for cattle and swine many poultry owners including my self successfully treat with Tylan50 for respiratory issues. its an excellent choice and packs a big punch. to pinpoint your birds exact illness would require a blood test. there are so many illnesses respiratory in nature it's unlikely to be able to successfully guess with out more symptoms or the blood work. but DO start the Tylan50 ASAP. you can get it at the feed store along with the syringe. I would chose this injectable over a water soluble antibiotic because it gets into the blood stream faster and dose is more controlled. good luck to you hope this helps.
