Nosebleeds in horses can occur for a number of reasons. Most are a one off, mild to moderate bleeds that settle within 15 minutes and are usually nothing much to be concerned about, but it is always worth a call to us to put your mind at rest.
Others can be more severe, prolonged and quite alarming. Some mild to moderate bleeds may reoccur. This can be due to an underlying cause that requires investigation and treatment by your Vet. Please do seek veterinary advice if at all concerned.
One of the most common reasons for a nosebleed is trauma.
A stick up the nose while grazing damages the delicate nasal mucosa (lining of the nostril) and causes a nosebleed, generally from one side. Your vet has to insert a nasogastric tube and, as inevitably sometimes happens, the tube causes a little trauma to that delicate nasal mucosa and the resultant nose bleed. Your poor horse gets a bash to the head and it causes a blood vessel within one of the sinuses mucosa to rupture. These bleeds can look alarming but are not a problem and should settle within 15 minutes. It can look like large volumes of blood but it’s worth remembering a little blood goes a long way and your average 500kg horse can lose 5 litres of blood with no issues.
So what about when these nose bleeds keep happening or they are severe with no apparent traumatic cause?
These are important to investigate. We will take a thorough history including frequency, approximate amounts (teacup or a bucket), odour etc. and based on our history and clinical examination we can carry out further investigations. Usually this involves endoscopy (passing a small camera up the nose and into the trachea and Gutural pouches) and radiography. We can then work out the cause of the bleeding and an appropriate treatment plan.
Some other causes of nose bleeds include;
Infections of the sinuses. These are often secondary to dental disease resulting in a tooth root abscess as some of the molar tooth roots are adjacent to the sinuses. Generally, bleeding occurs from one nostril and is usually accompanied by pus and an unpleasant odour. Treatment includes antibiotics and anti-inflammatories but the sinus may well need to be flushed via a small hole made into the sinus or, in long standing cases where the pus has dried and hardened, a larger flap and the pus physically removed.
Masses in the nasal turbinates. There are a few growths that occur in the nasal passages, causing disturbances in the delicate nasal turbinates (elaborate folds of thin bone located in the nasal cavity. These are lined with mucosa that improve the sense of smell and warm and moisten inhaled air to stop the lungs drying out). Like mucosa elsewhere, it is highly vascular and prone to bleeding if damaged. The most common, (although still unusual) mass is an ethmoid haematoma. These are ‘non-neoplastic’ i.e. they do not spread to other parts of the body and are not classified as a cancerous tumour. They are locally destructive as they expand and so termed a space occupying lesion. They cause an intermittent bloody nasal discharge, usually from one side but if it has expanded to involve the nasal septum then it may cause bleeding from both nostrils. The bleeding is not associated with exercise or trauma. Usually we see these in mature horses (8-10years old) and other clinical signs include respiratory noise (or even difficulty breathing if very large), coughing, head shaking, halitosis and even facial deformity. They can be diagnosed via endoscopy, where a glistening yellowish green, smooth mass is seen, and radiography can also be beneficial to determining the turbinate damage. Biopsy can help distinguish it from a benign polyp or a more aggressive tumour which are even more rare (e.g. a squamous cell carcinoma or adenocarcinoma). They bleed profusely if removal is attempted and have a 50% reoccurrence. Other treatments include injecting formalin into the mass and possibly laser surgery.
Gutteral pouch mycosis. This is thankfully rare but a potentially life threatening cause of epistaxis. Several low volume and intermittent bleeds unrelated to exercise may precede a catastrophic massive haemorrhage. The cause is a fungal infection of the guttural pouches (theses are air filled sacs that are outpouchings of the Eustachian tubes. They are located either side of the pharynx and below the ear). Large blood vessels and nerves run over its mucosal surface and are therefore vulnerable to disease. The fungus erodes the blood vessels and causes haemorrhage. It may also result in nerve damage causing difficulty swallowing, head tilt and facial paralysis. It is usually one side affected but it can spread to both guttural pouches. Diagnosis is tricky as stress can cause fatal haemorrhage but endoscopy is the primary diagnostic tool. Treatment is ligation of the effected blood vessel under anaesthesia.
Exercise induced pulmonary haemorrhage. Some horses, after strenuous exercise, may develop a nose bleed from both nostrils. Technically this isn’t a nose bleed as the blood actually originates from the lungs. Only 10% of EIPH cases exhibit blood at the nostrils. It is usually seen in the trachea when performing endoscopy, possibly as part of an investigation into reduced performance, coughing, laboured breathing or excessive swallowing. The cause is still being researched but the high capillary blood vessel pressures in the lung when a horse is a full gallop, coupled with possible chronic airway disease (e.g. allergic airway disease) and laryngeal dysfunction could be predisposing factors. Diagnosis is based on endoscoping within 90 minutes of exercise and by taking samples of fluid from the trachea and further down in the lungs. Treatment is rest but affected animals are generally predisposed to bleed again. Treatment and management of allergic airway disease and secondary bacterial infection is beneficial. In the USA, horses are allowed a diuretic before strenuous exercise to try and reduce blood pressure but it is debatable whether it helps and illegal in the UK. There are other drugs which claim to increase the capillary wall strength and stability but they are also a little dubious.
So, to conclude, most nosebleeds are nothing to be concerned about. Stay calm, monitor blood loss and let the horse rest. Don’t attempt to stem the bleeding with cotton wool/towel plugs like in humans as horses have to breathe through their nose. They cannot breathe through their mouths. So if your horse has a bilateral nosebleed plugging both his nostrils could cause him a more serious problem! Then please do call us for advice. Rarely, nosebleeds can be an indicator of a more sinister underlying problem so any severe or recurrent bleeds should be investigated!