Originally Posted by morganshow11
Nosebleeds are fairly uncomman in horses.
Actually, nosebleeds are more common than you think. It happens a lot it in barrel horses and other performance horses. Although it something to watch, my first thought would be induced pulmonary hemorrhage such as G and K's Mom had mentioned; generally these horses become labeled as "bleeders". There is a helpful article about it in this months Barrel Horse News, the OP might be able to find some helpful information there. Another idea would be to get information from your vet as well.
I would not worry a whole lot about it unless it becomes a reoccurring issue, defiantly something to keep an eye on though. Good Luck!