I have a standard laying hen that is about three years old and is a great layer, but recently I have noticed that she has/had lots of droppings stuck to her bottom, so I checked it out and her vent is very moist, gooey, red, puffy, and her butt stinks! I have tried looking this up but I didn't find anything on vent infections. I think she has been like this for a while now. So I put her in warm water and washed her bottom off and put her back with the flock. I checked her the next day and her vent is still oozing and the droppings are still sticking. I watched her all day and noticed that the rooster is mating her a lot more than the others, so I am thinking that she is either getting mated too much or she has an infection. I checked the other chickens and several others also have droppings that are sticking to their bottoms, but they don't have oozy, pussy vents. However, my white leghorn does and she even has a really dirty bottom. So I have separated these two, but I don't know how to treat them or how to get the droppings to stop sticking to the others butts. If it is an infection, can it be transmitted to the other hens if the rooster is mating them? The rooster looks fine. Should I be medicating all 40 of them or just the two?? I have been feeding them chicken scratch, egg maker, a little dog food, oyster shells, a little bit of DE, and sometimes they get at my goat's sweet feed. Should I be feeding them anything else to prevent their droppings from sticking or is this natural? Any help is greatly appreciated. I can post pics, but it is really gross.