I have six almost 3-week old chicks. The first 3 chicks I got via mailorder on May 1. There were actually 5 in that first batch but 2 died within 5 days of receiving them due to unknown causes; they just got lethargic and died. Two days after the second one died, I went to a local feed store and bought 3 more chicks (with the same hatch date as the first crew) and put them in the brooder with the remaining chicks. Thinking back, I probably should have kept these two groups separate for a while, but I was thinking integration would be easier because they were the same age. I wasn't thinking about the possibility of introducing outside diseases The only big difference between the two sets of birds is that the ones I got from a hatchery were vaccinated for Marecks, and the ones from the feed store were not. They are all eating medicated chick starter feed. Six days after getting the new chicks, one of the new chicks seemed to be sneezing. The next day, she sounded kind of raspy and wheezy. You could almost hear a gurgly sound if you massaged her chest/crop area. The thing that has me confused is that although she had these symptoms, there was no discharge from her eyes, nose, or beak. Also, she continued to eat and drink normally, activity level was normal, and had normal poops. Someone suggested I give her and the rest of the crew Sulmet mixed in with the drinking water. I did that, and within 48 hours her symptoms disappeared. Unfortunately, another chick (from my first batch of chicks) started with the same symptoms not long after the first one cleared up. The chicks had been drinking the water with Sulmet for about 72 hours when the second one started getting sick (and they're all still on it; today is day 5 of antibiotics). The second chick is acting normally (except for the cold symptoms) too, and no discharge from eyes, nose, or beak. My questions are 1). Most of the reading I've done about respiratory illnesses usually include symptoms of discharge from the eyes, nose, or beak, so what kind of respiratory illness do you think I'm dealing with? 2). Is Sulmet the best way to treat this, or should I use something else? The feed store where I bought the chicks from advised using Sulmet. 3). If this is day 5 of antibiotics, should I expect any of the others to get sick by now? 4). Another thing I've read with regard to respiratory illnesses is that even if a bird gets better, they'll always be a carrier of whatever it is that they had. Should I be concerned about this? We bought these chicks just so we could have our own supply of eggs. We will not have a rooster, and I am not interested in hatching eggs or selling chickens to other people. I am receiving another batch of chicks next month, but those chicks will be separated from the first crew for a while because they'll be six weeks apart in age. Thanks for any info. you can provide.