My chickens all have white specks, like dust, on their combs and faces. What is this? I can't find a definite answer anywhere. It's not dry pox. They seem fine otherwise. It just got colder here but we're in the south where it doesn't get very cold. It was about 32 degrees the other night, but that's a rarity. I'll take and post a picture. Coincidentally I gave them a small tub of yogurt yesterday so it could just be dried on yogurt, but it's odd that it's on all of them.