Many people use the procaine penicillin without problems, and since it is one of very few antibiotics to treat wound infections or egg yolk peritonitis available without mail order or from a vet, many have no other choice for a quick antibiotic to use. Even one of the Preparation H products contains pramine or pramocaine, a numbing agent, and could be harmful to chickens. I just feel if it isn't necessary to use a product with benzocaine, lidocaine, and others, it would be prudent just to use plain blood stop powder, that's all. If a -caine product is all you have and want to take a chance, it's good to know that there could be side effects. I feel like it is good for everyone to share their experiences here on the things they have used without side effects. A vet student on here did say that lidocaine was used routinely in surgery at her vet school without problems, but the dosage is probably the real issue in poultry, since lidocaine can affect the heart rhythm.