Join Date: Dec 2008
Location: At my house, or stable, duh!(Michigan)
Nosebleeds are fairly uncomman in horses. Trauma to the nose si your first possibility- a hard blow to the nose or a laceration or irritation to the nasal canal. But these don't happen that often.
I do not think horses are prone to dry sinuses or allergies, so I would assume that is not the case.
The big worry I would have is Guttural Pouch disease, which is the most comman causes of heavy nosebleeds. Guttural pouch is a pouch at the base of the horse's skull. Occasionally horses can get infection or bacteria into these pouches which can cause chronic problems. Worst yet, if they get a fungus there the fungus can slowly irritate the main arteries, and the horse can begin to have repeated nosebleeds. If left untreated the arteries will burst and the horse will rapidly bleed to death(which does not sound like it would happen to your horse since the blood is out of one nostril, adn not both).
I don't think it is horribly comman, but they do suggest that horses with nosebleeds be investigted for this as it is one of the main causes of nosebleeds. If this was my horse I would keep a close eye on her(like you said) for now. I would not be hauling her off to the vet after one minor nosebleed. But if I found heavy bleeding in the snow after this, or repeated minor bleeding, I think I would be visiting a good equine vet soon.
I hope you wont be too paroniod with my comment about gluttal pouch mycosis. But I wanted you to know a worst case senario in case the nosebleeds continue. Hopefully this was a one time thing and it wont happen again!