The key thing to remember if your horse has a nosebleed is not to panic as, although a nosebleed in a horse can appear both dramatic and distressing, in many cases the bleeding will frequently stop of its own accord.
It is important to assess how much blood is being lost, if you can count the drips then keep assessing it and seek veterinary attention if it hasn’t stopped in half an hour or significantly worsens, however, if the blood is pouring out then a vet is needed immediately as it may be a case of guturral pouch mycosis which is a rare condition that is often fatal.
It is also helpful if you are able to explain to the vet which nostril the blood is coming from as blood will usually only emerge from one nostril if the bleeding is coming from the head, however, bleeding from the lungs will come out of both nostrils (e.g. exercise-induced pulmonary haemmorrhage). The commonest cause of a nose bleed is a simple knock on the head, which, although can produce a large amount of blood, are usually self-limiting.
A moderate nosebleed, if accompanied by coughing, suggests a foreign body wedged in the nose or throat.
Occasionally tumours somewhere in the respiratory tract, or inflammation of the horse's sinuses (sinusitis), will produce a trickle of blood from the nose.
As previously mentioned the most common reason for blood coming down both of a horse's nostrils) is blood coming up from the lungs in exercise-induced pulmonary haemorrhage (EIPH). If a horse continues to have nosebleeds this should be properly investigated usually by performing endoscopy (looking down nasal passages and trachea and into the lungs) and taking x-rays of the head.