I wrote the details here: https://www.backyardchickens.com/forum/viewtopic.php?pid=4926877#p4926877 in hopes other folks can help me prevent this from happening to the rest of our geese. Briefly, I put him outside this morning to benefit from the fresh air & sunshine. He didn't seem any worse, and a bit better. At 1pm we brought him in to give him his second injection, and as my son was holding him Big Bird bent his head & clear mucus flowed out. I gave him his injection but he died about 5 minutes later.
I need to know what to do for the rest of my remaining geese, so this doesn't take them too. Should I give them the antibiotic too, just in case?