Here's some information about treating Vent Gleet.
https://www.tillysnest.com/2012/12/vent-gleet-prevention-and-treatment-html/
I'd check the hens over for lice/mites and make sure the crops are emptying overnight.
If the respiratory distress is caused by a Virus, an antibiotic will not help, usually the Virus will just have to run it's course.
If the respiratory distress is caused by a bacterial or bacteria-like disease like Mycoplasma, then Tylosin (Tylan), Tiamulin (Denagard) or a Tetracycline can be used to treat symptoms.
You mention giving Tylan. Was that water soluble Tylan(Tylosin) or the Injectable Tylan50 or 200?
Tylan/Tylosin is bitter and if it's the soluble in the drinking water, the hen must drink. If she didn't drink very well, then she likely didn't get enough medication. You may have to syringe the medicated water into her several times a day.
Injectable Tylan 50 or 200 can be given orally. But it needs to be given 3X a day for 5 days in a row.
Injectable Tylan 50 dose is 0.25ml per pound of weight given orally 3 times a day for 5 days.
Injectable Tylan 200 dose is 0.05ml per pound of weight given orally 3 times a day for 5 days in a row.
Hopefully your hens will improve.
https://www.tillysnest.com/2012/12/vent-gleet-prevention-and-treatment-html/
I'd check the hens over for lice/mites and make sure the crops are emptying overnight.
If the respiratory distress is caused by a Virus, an antibiotic will not help, usually the Virus will just have to run it's course.
If the respiratory distress is caused by a bacterial or bacteria-like disease like Mycoplasma, then Tylosin (Tylan), Tiamulin (Denagard) or a Tetracycline can be used to treat symptoms.
You mention giving Tylan. Was that water soluble Tylan(Tylosin) or the Injectable Tylan50 or 200?
Tylan/Tylosin is bitter and if it's the soluble in the drinking water, the hen must drink. If she didn't drink very well, then she likely didn't get enough medication. You may have to syringe the medicated water into her several times a day.
Injectable Tylan 50 or 200 can be given orally. But it needs to be given 3X a day for 5 days in a row.
Injectable Tylan 50 dose is 0.25ml per pound of weight given orally 3 times a day for 5 days.
Injectable Tylan 200 dose is 0.05ml per pound of weight given orally 3 times a day for 5 days in a row.
Hopefully your hens will improve.