Have a small herd of St. Gertrudis cattle that have started have a white discharge from their eyes. It started as just clear but now is turning white. Started with only 1 cow being affected, but has now spread to 2 more, with 1 at the clear stage. Eyes themselves do not look cloudy, nor are they squinting their eyes as if the sun is causing discomfort. Appetites are normal. Any ideas as to what this might be?