Disclaimer: one person's experience with one batch of ducklings. Nothing scientific about it. Posting because maybe it will help someone else. A few days ago I received a batch of ducklings in the mail. They'd been 2 days in transit and the weather has not been premium for shipping. All ducklings arrived lively, hungry, thirsty, and peeping. Good, right? Except 5 of the ducklings had droopy eyelids, like they were sleepy. Unfortunately, I decided they needed rest and left them undisturbed for 5 minutes until I reached the conclusion I really didn't like the way their eyes looked. In that 5 minutes, one of the ducklings had died and the other droopy ones looked even droopier and one had some nasty diarrhea. I put some Tylan into their drinking water. The droopy ducks had bills full of mucus. I washed their bills out and made sure they drank the Tylan water. Every 5 minutes I made sure they swallowed at least one mouthful. They did not want to drink so I didn't just leave them with the medicated water. I made sure I saw them swallow. It's now 48 hours and no more losses. I can't pick out which ducklings were sick. I've removed the medicated water and added yogurt to their water (Tylan is a short usage antibiotic, follow label directions and always give a full course of antibiotic) I chose the Tylan because it is the strongest antibiotic I've got and the very first approved use on the label is for respiratory for poultry, so it is on-label use. Possibly any antibiotic might have worked, I don't know. Terramycin is good for respiratory and it is approved for poultry. It's also a heck of a lot cheaper than Tylan and a lot easier to find. Most feed stores will carry it. I've got terramycin in my fridge but didn't use it. Lesson learned. I'll be paying close attention to how the eyes look on any more poultry I get shipped in. Even the slightest suspicion about how they are feeling and I'm not waiting for symptoms to develop. All these guys looked fine and lively and it was literally minutes before they started dying. The only thing off about them was the sleepy looking eyelids.