One of my hens looks like she has been dragged through mud puddles, and she is acting strange. Her backside feathers look like she could use a good bath, and all over she just looks greasy-dirty, as if she is not preening at all. All other 14 in the flock are fine. This one is also hiding a lot more than usual, is timid, but she still wanders around and is eating and drinking and going in and out of the coop just fine. Should I quarantine her? Give her a bath? Just leave her alone? It is possible that one of my dogs may have played with her. I have found on occasion that they will trap a hen between their paws and lick on them (..tastes like chicken?) until they get all sloppy looking, but after drying out they are just fine. This hen has looked like this for 2 days. Is there a condition that makes one stop preening?