Reasons for Nosebleeds in Horses

Seeing blood coming out of your horse’s nose is terrifying. Especially when it happens randomly. Nosebleeds in horses are known as epistaxis.

There’s a few reasons horses can experience epistaxis:

• The horse has banged their nose/head. This is perhaps the most obvious reason for nosebleeds in horses. Just like a human who hit’s their nose, horse’s can get nosebleeds from hitting their heads. If a bump to the head is the reason, the amount of blood can vary from a small trickle to gushing.
• Another reason is dryness or dust in the environment. When the weather is extremely dry, in either cold or hot weather, small capillaries in the horse’s nostril can burst just like in humans. Surprisingly this isn’t something I’ve found much information on when doing research, but I confirmed it with my vet. Typically in this case, the amount of blood will be small. 
• If the nosebleed starts during exercise you might want to consider Exercised Induced Pulmonary Hemorrhage. Horse’s with this disorder are often referred to as ‘bleeders’. What happens is that when the horse experiences intense exercise, such as racehorses or barrel racers, capillaries in the horse’s lungs burst causing blood to pool in the lungs and fill the airways. While it sounds terrifying and it can be, EIPH is rarely fatal and can be managed. Only a small percentage of horses actually bleed from the nostrils with this disorder. Typically they bleed from both nostrils, but can bleed from just one. Other indications of EIPH is coughing after intense exercise (an attempt to clear their lungs) and a change in performance. This page from barrelhorse.com and this one from equimed.com are both good places to start for further information on EIPH.
• Guttural Pouch Mycosis can cause reoccurring nose bleeds. The guttural pouch is near the horse’s inner ear and can sometimes get infected primarily with a fungus. This infection can cause moderate to severe nosebleeds and should always be attended to by your vet. For more information on this check out this site.
• Occasionally tumors can cause minor nosebleeds. 

The key here is that while nosebleeds in horses can be as simple as dry weather they can be indicative of a larger problem. If you see blood in your horse’s nose, even if it seems like a minor amount contact your vet, and think about your horse’s behavior. Have their eating habits changed? Are they coughing more? Are they suddenly under performing? Thinking about these things can help you decide how serious your horse’s nosebleed might be, but always let your vet decide.