Possible eye infection. Further spread prevention?

[wayward]

As of today, two of my roosters have come down with some sort of eye infection. There's no swelling, some puss, and its pushed their eye way back into their head.

The second one we spotted today, I wiped off some eye foam with my shirt and brought him inside to clean out the puss. His eye has resurfaced, but he's keeping it partially closed. The entire flock has been given antibiotics, Tetracycline is the only medication I currently have access to. I'm not actually sure of its applications in this scenario, or if I should pick up a different antibiotic.

The first rooster displayed this problem yesterday, I wasn't home at the time but my girlfriend cleaned out his eye and put a bandaid over it. For the past couple weeks some of the chickens have been sneezing, but not at any alarming frequency.

Help? I'll try to get pictures whenever I can.

Edit: Doing some additional research, it appears to be Coryza and I'm going to seek out Tylan 200 to treat the symptoms. I have ample space to contain "carriers" if a culling can be avoided (Though I'm willing).

I have multiple coops with fully-closed pens keeping my other flocks from direct interactions, the infected flock is free-range and does spend time "around" the fences. Are the contained chickens at any risk of infection? What medications can I use to prevent possible infection while they're still healthy? I just put out into these contained pens a new batch of silkie chicks and a batch of various 2-month old pullets, I would hate to have to start over on this grand of a scale.

 

[Eggcessive]

Is there a bad odor from the 2 sick chickens? MG (CRD) and coryza can appear similar, and testing is the only way to know for sure. Tylan50 is what most use for shots in chickens, and Tylan200 is 4 times as strong. Both of these are contagious and could possibly spread to your other chickens. Treating them before they get symptoms is not something I would do. Sending one of the sick chickens off for a necropsy to be put down would be something you could do to find the exact disease, and if there are any secondary infections. I would think about culling the two sick chickens since it would be difficult to contain this disease from the whole flock. Here is a good link to read about the different diseases and symptoms and a link for your state vet:
http://edis.ifas.ufl.edu/ps044
http://www.aphis.usda.gov/animal_health/animal_dis_spec/poultry/participants.shtml

 

[wayward]

Thank you for your quick response and for the useful resources. I'm sorry as I didn't mean to imply I was going to give shots of Tylan to my entire flock. I've isolated the infected chickens and gave them each a size-appropriate dosage. In only one day I'm seeing significant improvements, particularly in the second case because we were able to treat it the quickest. I'm not going to jump to conclusions, but research and examination still points to coryza. I'm cautiously optimistic.