How old are these birds? It sounds to me like it might be gleet. It'a a yeast infection and it causes a white nasty discharge from the vent. I don't know what the penatin is, but am assuming it is for diaper rash. if it is, then sure, it can't hurt. As a woman, at some point you've probably gone through the joys of a yeast infection so know what's what. Not a lot of fun shall we say? To treat, you should start giving them a good probiotic in their water or sprinkled over their feed. This will help to balance out the gut and hopefully get rid or it. I use a human probiotic called FloraGen3. It's a little pricey at $25 a bottle but it has a long shelf life if kept in the fridge and you shouldn't need the whole bottle of 30 capsules. You'd have to ask for it at the pharmacy as it has to be kept cold. If you decide to go this route, just open the capsule and sprinkle it over their feed once a day. I generally mix it into their feed by hand before adding the food to their feeder, this way I know it all gets covered with some of it.
