Two mares at the my stables that belong in the same paddock (including my mare) have suddenly gotten some eye discharge. I noticed my mare's left eye wasn't swollen, but had a creamy white-ish sorta yellowy discharge, but most of it was clear, that I had to wipe away. This only happened for, at the most 1 and half days. And then one of the miniature mares in her paddock also had the same thing, but only for a day or two. I looked, but I didn't notice anything wrong or stuck in their eye other than the discharge that I had to wipe off. Could this be allergies? Or something else I should look out for? No other horses have this in their paddock or in the rest of the barn.