http://edis.ifas.ufl.edu/ps044 How old are your birds?
Terramycin/tetracycline is effective against many of the infectious upper respiratory bacterial diseases, but not all. Not coryza. It won't work if they do not get an effective dose (meaning if you put it in their drinking water, and they are too sick to drink enough, or if the mix is too old (change daily), or if you didn't use it for long enough.
Sulfadimethoxine (albon) is typically used for coccidia- which is not a respiratory disease, not a bacteria. It is also used for some respiratory diseases. It is labeled for coryza in CERTAIN poultry. Also will only work if used correctly and they are drinking the water soluble stuff.
Aureomycin (chlortetracycline) is another antibiotic in the tetracycline class. Unlikely to help you if you used the terramycin correctly.
Tylan/tylosin different antibiotic class from the tetracyclines and sulfa drugs, but it has alot of overlap with the antibacterial spectrum of the tetracyclines. It may or may not work depending on your bug.
You could even have a virus. Or a respiratory parasite. Probably a bacteria though.
Many of the upper respiratory diseases look the same, but can be differentiated by age of bird, how sick they get/how many die, what body part is the most severely effected, how fast they got sick from exposure- a vet can test the bird, or you can send a deceased bird to your state lab. Talk to your local poultry extension agent, or your vet can direct you to the right place.
Jess
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