A nosebleed in a horse can appear both dramatic and distressing, but in many cases the owner is more worried than the horse and the bleeding will frequently stop of its own accord. The key message is ‘do not panic’ – instead, assess the situation.

Surveying the damage

It is important to ascertain the following:

  • How much blood is being lost?
    Even a small bleed can look dramatic, especially down the front of a grey horse. Equally, a large bleed can be concealed under bedding in a stable, so it helps to estimate the severity: would the drips slowly fill a teacup or rapidly overflow a bucket?

    Most minor nosebleeds stop within 15 minutes, but if a Thoroughbred-sized horse loses more than four litres of blood rapidly, it needs emergency treatment.

  • Is the blood coming from one nostril or two?
    This information is helpful in order to forma diagnosis, since if it is a true nosebleed originating from withing the horse’s head, blood will usually only emerge from one nostril, on the side of the head that is affected. A horse that is bleeding internally from the lungs will bleed from both nostrils.

  • Is there any obvious reason for the bleeding?
    For example, the horse may have just knocked its head in a fall, or is can occur if the vet has just passed a stomach tube up the nose.

  • Is it a one-off nosebleed?
    If so, this suggests a rupture in a minor blood vessel. On the other hand, if nosebleeds occur repeatedly, then this suggests potential damage to a more major artery, which needs investigation.

  • Has the horse just been exercising hard?
    If so, it is most likely to be suffering from an exercise-induced pulmonary haemorrhage.

    Common causes of nosebleeds

    Horses do not tend to have spontaneous nosebleeds, so even if you are not aware of a possible reason, b e suspicious – there must be a cause.
    A nosebleed – properly termed epistaxis – occurs when any part of the nasal passages (which are richly supplied with blood vessels), throat, lower airways or lungs are injured to such a degree that blood vessels are damaged and blood leaks out.

    The commonest cause is a simple knock on the head, when alarmingly large amounts of blood may pour from one nostril. Such traumatic nosebleeds are usually self-limiting, but always consult your vet.

    Another common reason for a nosebleed is if the delicate nasal tissues are knocked inadvertently when a vet passes a stomach tube up from the nostril. Sometimes this is unavoidable, particularly if the horse moves at the wrong moment – however, the bleeding always stops.

    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.

    The most common reason for blood coming down both of a horse’s nostrils (properly called bilateral epistaxis) is blood coming up from the lungs – so technically it is not a nosebleed at all.

    Exercise-induced pulmonary haemorrhage (EIPH) refers to bleeding from the blood vessels within the lung and is probably the most common abnormality affecting the horse during exercise.

    Such horses are sometimes called ‘bleeders’ or described as having burst blood vessels.

    The condition is not new, having been reported by the Greeks and Romans, but it has become much more clearly understood with the use of modern flexible endoscopes, which have allowed vets to see that the blood does indeed come from the lungs.

    It is now understood that the bleeding originates from the delicate pulmonary capillaries in the lung and occurs when these tiny, thin-walled blood vessels are put under extreme pressure by the huge air-and blood-flow demands associated with the galloping horse.

    There are various theories as to exactly how these blood vessels are affected, but somehow they are damaged and this results in bleeding into the lungs.

    Symptoms of EIPH
    Signs to watch out for include:

  • A nosebleed, usually from both nostrils after exercise
  • Coughing
  • Poor exercise performance

    In severe cases, bleeding is sufficient to well up through the airways and appear at the nostrils, but in the majority, the blood does not get that far and is reabsorbed, as it may be less than a teaspoon in quantity. Very rarely, a horse may sustain a fatal bleed from the lungs, generally towards the end of a race r the cross-country phase of a competition.

    As EIPH may affect performance, particularly in racehorses (around one in every 1,000 horses racing in the UK ends up with noticeable bleeding), it has attracted a lot of research effort – but it is not just racehorses that are affected. Following intense exercise, all horses break some of the smallest blood vessels in their lungs and EIPH can also affect horses used for cross-country, polo and show jumping, as well as some draught and endurance horses.

    What are the possible causes?

    The chances of EIPH are known to increase with:

  • speed of exercise
  • Age
  • The presence of any kind of disease of the horse’s lower airways, such as stable coughs and dust allergies – horses kept in dirty, dusty environments suffer more.
  • Abnormal blood clotting
  • Upper airway obstruction, such as roaring or gurgling – that is, if a horse makes a respiratory noise

    The treatment for horses that have had episodes of EIPH includes rest and anti-inflammatory medication, such as bute. A gradual return to training is usually recommended, together with efforts to ensure good hygiene to reduce small airway inflammation.

    Frusemide (brand name Lasix or Salix) is a popular treatment, but is banned in Thoroughbred racing in the UK (yet not in all states of the USA). The use of nasal strips (brand name Flair) has been shown to help, by making it significantly easier for horses to breathe during strenuous exercise.

    Such devices help open up the airway and reduce the turbulence of the airflow as the horse breathes – very important during fast work. They are banned in UK Thoroughbred racing, but have been seen on the noses of several successful event horses going cross-country recently.

  • This article appears in full in September’s HORSE magazine, on sale now.