I have Tylan 50 and injectible penicillin g procaine on hand, but have never had to give a shot before. Know it's iffy that these will work, but I have to try. Sydney's a 1 year old Australorp, head of the pecking order and normally a great layer and friendly bird. Poor girl. The area below her vent is very swollen, like a water balloon. I've isolated her in a dog crate, given water and scrambled egg, but she's hardly eating or drinking and very lethargic. At first I thought she was egg bound, so I soaked her in warm water. After all the poo was off, I could get a better look. Gently inserted some olive oil with a syringe. Then probed with gloved finger and realized the swelling was below the vent and was not firm. So did internet research and it sounds just like egg yolk peritonitis. But I can't find how much and what kind of antibiotic to give her.