Join Date: Oct 2011
Location: Illinois www.saddleonline.com
Yellow snot usually means some sort of infection- if it was clear or white I wouldn't worry, but yellow and green are not good. I would take his temperature and see if he has any sort of low grade fever, and call the vet. If it is that he caught something, you will be much better off treating it early that waiting to see if it gets bad.
Best of luck!
"Riding: the art of keeping the horse between you and the ground."