I have 24 chickens. 2 White Leghorn roosters. 1 White Leghorn hen, 2 Black Aussie hens, 1 mixed breed rooster and 19 Production Reds. The chickens have been outstanding all winter here in eastern Oklahoma. I have been getting 15 to 21 eggs every day since late summer. My concern is on 1-28-2014 I found the white hen on the floor of the chicken coop almost frozen. She was very cold and stiff. I brought her in the house and after a couple of hours she warmed up but has never recovered to the point where she can be returned to the flock. She eats and drinks well and her droppings are normal but seems to suffer from vertigo. This morning, 1-31-2014, one of the white roosters was also having symptoms of vertigo. In fact, he was staggering so badly, he was easy for me to catch. I brought him into the house and put him in the cage with the white hen. He too has a good appetite but just has a hard time keeping his balance. All the other chickens seem to be well at this moment. Any ideas on what is happening to my White Leghorns or is this just coincidence? Of course I am worried this will go thru the whole flock.