Nosebleeds in horses
Epistaxis is the veterinary term used to describe bleeding from the nose. In horses this is a fairly common complaint and has a number of potential underlying causes. Nosebleeds in horses can be very dramatic, understandably causing a lot of distress for owners, however in most cases the bleeding is self-limiting so it comes to a stop on its own. Although it can seem that the horse is losing a large volume of blood, it´s important to remember that the horse is a big animal, and in many cases can lose several litres of blood with no compromise to the body or significant effect on him. In occasional cases horses can lose enough blood to cause a problem, and the signs of this can include pale gums, fast pulses and weakness. It´s important to get to know your horses normal parameters like heart rate (get used to checking your horse´s heart rate with a stethoscope), gum colour, temperature, and so forth. A reference guide can be useful to refer to, but always call your veterinarian if your horse has a nosebleed out of the blue so they can advise what to do next. A lot of nosebleeds stop without intervention but occasionally a severe bleed from a large vessel can be life threatening, your veterinarian will tell you if the horse needs to be seen right away.
What causes nosebleeds in horses?
There are a number of different causes of nosebleeds in horses that occur fairly frequently. In racehorses and other horses that perform at high athletic capacity, a common cause is a condition known as Exercise Induced Pulmonary Haemorrhage (EIPH). This is where small blood vessels in the lungs are put under extremely high pressures when the horse is undertaking strenuous exercise and this results in them bursting. The blood from these small bleeds then flows down through the trachea and can be seen at the nose but sometimes will only be appreciated if the horse is undergoing investigations for poor performance, where the bleeding can be seen on endoscópic examination of the lower airways.
A particulary worrying cause of equine nosebleeds can occur because of a condition called gutural pouch mycosis. The anatomy of the horse´s head is different in that the eustacian tubes extend into pouches called the gutural pouches, these connect with the pharynx and there is one on the left and the right sides of the head, maybe take a look at an anatomy book to get familiar with the horse´s head. These large airfilled spaces can be susceptible to a fungal infection (mycosis) and problematically through the gutural pouches also run a couple of very important nerves and blood vessels. When a horse suffers from gutural pouch mycosis the infection can be quite extensive and it can latch on to the Surface of these structures, this means that if it erodes through the nerve the horse can have neurological abnormalities, and unfortunately if it eats through the blood vessel wall the horse can suffer heavy, sometimes life threatening nosebleeds.
In some horses upper airway infections can cause damage to the delicate tissues of the nose and the bony holes inside the skull known as sinuses. These infections can also be associated with bleeding but they are often indicated accompanied by a purulent nasal discharge that is blood tinged rather than being frank fresh blood as in the above forms of bleeding at the nose. The sinuses can also develop tumour-like lesions inside them called ethmoid haematomas, these can cause nosebleeds as they can extend through the bony tissue into the nasal cavity.
Sometimes quite impressive bleeding can be seen from the nose when a nasogastric tube is being passed – for example, for a horse with choke, or colic. This is really quite common and isn´t anything that has been done wrong in passing the tube, the reality is that the back of the nose where the tube must pass in order to ge tinto the oesophagus is very well vascularised and easily irritated which can lead to this bleeding, thankfully most of these cases bleed heavily for just a short time before the body´s own clotting mechanisms take over and it stems with no further ado, but it can look very dramatic.
How are nosebleeds investigated and treated?
In a horse that has a nosebleed for no apparent cause, it´s possible your veterinarian will suggest some further investigation to figure out why. In mosst cases this starts with a thorough physical exam to rule out bleeding from anywhere else and identify any obvious cause, and it can be helpful to do an examination of the horse´s mouth and teeth. Depending on the suspicion of where the bleeding is arising from an endoscopy of the respiratory tract (passing a camera down the trachea) may be recommended, as well as the appropriate tests on fluid collected from here. Sometimes the camera needs to be used to examine the inside of the nose, the back of the horse´s mouth (the pharynx) and the gutural pouches to check for evidence of disease here, again simples are often collected and sent off for analysis. Finally in occasional cases chest xrays might be needed although given the size of the average horse these have their limitations, they are particularly useful for foals who have a smaller body size more amenable to radiography.
The treatment of nosebleeds really depends on the underlying cause, in some cases specific treatment is not necessary but where abnormalities are confirmed your veterinarian will be able to advise whether oral medications or surgery are needed to get the horse back to health.