I was going to put flea collars on everyone and I asked the vet if they would put the flea collars on the feral cats while they were asleep, but they said they would not work that great and the ferals could get hung up on a tree or fence or something. I have always used flea collars and they have always worked fine. Even if I do decide to use flea collars now, I have no way to get them on the ferals. I don't know what to do.