My Pekin duck has had common eye infections before in the winter when she couldn't flush it out properly. Her symptoms were; irritation around the eye, milky substance in eye, swollen and not opening the eye. I'm seeing that she may be starting to get it again. She's squinting and the feathers around her eye are slick with a miscellaneous liquid. I want to treat it or try to stop it before she gets it again. Since I may be paranoid or it might be something else but I don't want to give her any kind of drug or medicine unless necessary. She has access to a pond and clean drinking water constantly but we'll drain and refill the pond anyways just in case. I read last time this happened that you can use apple cider vinegar in their water to build their immune systems to fight off the infection. I can't find the original post so I've resorted to creating my own. I want to make sure I put the right amount of ACV in the water and that it's safe for them to drink. I figure using this would be safer then giving her drugs or waiting until the infection gets worse. Any advice would be fabulous I don't want to poison my ducks by accident.