Nosebleeds may look dramatic but are fairly common in all types of horses. Small one-off bleeds are often inconsequential, but frequent, prolonged haemorrhaging could be a sign of a serious underlying condition.

One-off bleeds

THE cause of some nosebleeds may be obvious, such as a blow or kick to the head, but horses can have a mysterious one-off nosebleed that drips for no longer than five minutes and never recurs. The reason behind the bleeding may never become apparent and there may be no cause for concern or need for further investigation. However, if a second nosebleed occurs, large quantities of blood are lost or the bleeding continues after 20 minutes, you should call the vet.

Exercise-induced pulmonary haemorrhage

NOSEBLEEDS are not an uncommon sight in the hunting field or on the racetrack and can be the result of short periods of intense, fast exercise. These can cause an exercise-induced pulmonary haemorrhage (EIPH) where pressure on the lungs causes small capillaries to burst and the resulting blood drains out through the nostrils. These nosebleeds may look spectacular and can limit racing performance.

Endoscopic investigation

IF a horse has more than one nosebleed a vet may carry out an endoscopic examination to ascertain the source of the problem. This is a clinical investigation of the airway that involves passing a flexible tube up the nostril and towards the lungs.

Endoscopy is vital to detect the rare, but potentially fatal fungal infection of the guttural pouches, as well as for making more straightforward diagnoses.

Guttural pouch mycosis

VERY occasionally horses can contract a fungal infection in the guttural pouches which erodes through the carotid artery and can cause uncontrollable haemorrhaging and death. This is known as guttural pouch mycosis and usually starts with a few warning bleeds. This is something vets will check for when investigating a nosebleed. A warning bleed would involve bright red arterial blood and, after the bleeding stops, a dark red-brown discharge would be evident over the next few days.

This article was first published in Horse & Hound. To read in full, see 9 October 2008 issue.