Epistaxis (Nosebleed) in Horses

Courtnee Morton, DVM
By Courtnee Morton, DVM on Apr. 25, 2022
Close-up photo of horses mouth. Very shallow DOF, selective focus on the nose area.

In This Article


What Is Nosebleed in Horses?

Bleeding from the nostrils is medically termed as epistaxis. It may originate from the upper or lower parts of your horse’s respiratory tract. Epistaxis is a clinical sign that may be observed with many different conditions. There are no breed-specific causes of epistaxis in horses, although certain populations are much more likely to show this symptom. Racehorses, or athletes who undergo intense exercise, are prone to nosebleeds.

Symptoms of Nosebleed in Horses

Bleeding may be observed as a tiny trickle or heavy gushing from one or both nostrils. Blood may be mixed with mucus, pus, or froth. Nosebleeds may be seen at rest or after exercise.

Causes of Nosebleed in Horses

Nosebleeds may be caused by several different conditions, including:


Facial bone or skull-base fractures can occur from a kick, trailer accident, etc. These are the most common causes for nosebleeds in young horses that are not athletes. A nosebleed is often seen after a horse flips over backward and hits its poll. This can rupture the longus capitis muscle where it attaches next to the guttural pouch which leads to significant bleeding.

Progressive Ethmoid Hematoma

This is a non-cancerous mass that grows over time. Typically, red-tinged mucus is seen from one nostril intermittently, sometimes after exercise. However, bilateral bleeding/nasal discharge can also occur. Horses may have a foul odor when the face is approached, or they may have exercise intolerance.

Exercise-Induce Pulmonary Hemorrhage (EIPH)

EIPH affects most, if not all, intensely exercised horses to some degree. Risk factors include racing in temps below 68 degrees Fahrenheit and a higher number of lifetime starts. Post-race epistaxis, which is a sign of severe EIPH, is more commonly observed in older racing animals, in mares, and after shorter, more intense races. When a horse is racing, extreme respiratory effort is exerted, and their blood pressure is increased. During this severe hypertension of the tiny blood vessels in the lungs, there can be a “stress failure” of the capillaries, allowing blood into the lungs.


Sinusitis simply means inflammation of the sinuses, which can lead to decreased airflow, respiratory noise and occasional bleeding. Horses have six pairs of sinuses, so there is a lot of room for potential infection in this area. These typically occur due to infection of viral, bacterial, fungal, or parasitic origin, but can occur with cysts, neoplasia or polyps. Often, this is a unilateral disease process unless the cause is viral or there is extensive local involvement, so you may only see discharge/blood from one nostril. The most common viruses that may cause sinusitis include equine influenza virus (EIV) and Equine Herpesvirus 1 and 4 (EHV).

Guttural Pouch Mycosis (GPM)

This is a severe infection of the guttural pouches, most often caused by the fungus Aspergillus fumigatus. Fungal plaques grow in the pouches and often encroach upon one of the carotid arteries. The most common clinical sign is a bright red (arterial) discharge from one or both nostrils. Usually, a moderate initial bleed will occur and resolve uneventfully, then a more severe or even fatal bleed will occur within the next several days or weeks.

Neurological signs (droopy face, respiratory distress, trouble eating) can often be seen if the nearby cranial nerves are affected. If you see a bright red nasal discharge lasting for more than a few minutes, call your veterinarian right away.


Thrombocytopenia, or lack of platelets, can lead to prolonged bleeding after trauma, after venipuncture, or if an underlying disease process is occurring.

Disseminated intravascular coagulation (DIC) occurs when platelets become overactive and clump together inappropriately in some locations, leading to severe hemorrhage in other parts of the body. This is typically seen in the end-stage disease process from infection, inflammation, etc. Once this process occurs in a horse, it is typically fatal. Bleeding may be seen from the nose, urinary or GI tracts or it can occur internally.


Nasal passage masses/tumors may be seen. Primary lung tumors are uncommon in horses, although metastatic masses are occasionally observed. Chronic coughing, weight loss, exercise intolerance, and increased respiratory rate and effort might be observed.

How Veterinarians Diagnose Nosebleed in Horses

Veterinarians may perform several tests when horses present nosebleeds. These include:

  • Endoscopy: An endoscope allows for visualization of the respiratory tract from the nasal passages to the first split of the trachea stemming to the lungs. This exam can be performed while the horse is awake or slightly sedated, and at a minimum diagnose the anatomical source of the bleeding.  

  • Bronchoalveolar Lavage (BAL): This procedure allows vets to collect samples from the airway themselves. Saline is washed into the trachea, or a branch of the lungs, and then retrieved. Bacteria, blood, and other abnormal cells can be identified in the fluid.

  • Radiography: Radiographs allow for examination of the bony structures in the skull and upper respiratory tract. Although confusing to look at with so many small bones overlapping, vets can often see fractures, masses or fluid buildup within the sinuses.

  • Advanced Imaging: CT (computerized tomography) or MRI (magnetic resonance imaging) can provide a more detailed imaging analysis if the exact mass location or distribution is uncertain.

Your veterinarian will perform a thorough physical examination, including paying special attention to the heart. Horses with atrial fibrillation (an abnormal heartbeat in which the upper chambers of the heart quiver or beat too fast) have a higher pulmonary arterial pressure than other horses, so they are more susceptible to experience nosebleeds if they are high-performing athletes. Vets may also perform bloodwork to check platelet levels, particularly in severe bleeding episodes.

Treatment of Nosebleed in Horses

In severe, acute cases of nosebleeds with massive blood loss, IV fluids are necessary to help replace lost volume, and blood transfusions may be performed.

In cases of a progressive ethmoid hematoma, a series of injections of the lesion with Formalin is the most popular treatment method, followed by a laser treatment. Surgical removal predisposes horses to significant hemorrhage, which may lead to the horse needing a blood transfusion.

In cases of EIPH, furosemide (Lasix) is a diuretic used to treat bleeding symptoms. Cases of guttural pouch mycosis require the infusion of antifungals into the guttural pouches. Systemic antifungals can also be used as needed. Other causes of nosebleeds may require repeat flushing of the nasal sinuses, antibiotics and anti-inflammatories such as flunixin meglumine, steroids, and supportive care.

Recovery and Management of Nosebleed in Horses

Your veterinarian may recommend a controlled exercise program for horses with frequent nosebleeds. After any nosebleed, monitor for coughing, increased respiratory effort and fever. Some nosebleed episodes may predispose horses to pneumonia or other secondary complications.

Nosebleed in Horses FAQs

Is a horse nosebleed serious?

If your horse has a nosebleed lasting longer than five minutes, or has repeat episodes of bleeding after exercise, it should be examined by a veterinarian.

What to do if a horse has a nosebleed?

Move your horse to a quiet area and try to prevent them from raising their head up high to prevent blood from running down the trachea into the lungs. Feed the horse on the ground to let the blood flow out—if it’s not an acute gushing of blood.

Is EIPH fatal?

EIPH is rarely fatal, but severe post-race bleeding can occur and should be treated immediately.

Featured Image: iStock.com/zlisjak

Courtnee Morton, DVM


Courtnee Morton, DVM


Dr. Courtnee Morton is a 2017 Ross University School of Veterinary Medicine graduate. Since graduation, she completed an equine internship...

Help us make PetMD better

Was this article helpful?

Get Instant Vet Help Via Chat or Video. Connect with a Vet. Chewy Health