One of the more common phone calls we receive concerns a horse having a nasal discharge. These can be insignificant or very significant depending on the amount and type of discharge. Probably the most serious discharge is a hemorrhage out of the nose, although most of these are not an emergency as most are an exercise-induced pulmonary hemorrhage. Exercise-induced pulmonary hemorrhage is usually noted after an event that requires all-out performance and the hemorrhage noted at the nose is usually very small drops of blood.
However, one condition resulting in a severe nose bleed can be deadly, and this bleeding occurs due to a fungal infection in the back of the horse's nasal cavity. The fungal infection damages a major blood vessel in the area and causes it to rupture. If this vessel ruptures, the bleeding can be so severe it can lead to death. If a large amount of blood is noted from the nasal cavity, emergency surgery is usually required and the horse needs to go to a surgical facility immediately. Trauma, such as the horse running into a wall or falling and landing on the head, can also cause bleeding but usually these bleeds are limited and there is little chance of losing a significant amount of blood.
Another cause of nasal bleeding is a mass called a progressive ethmoidal hematoma and these masses usually cause intermittent bleeding from one nostril only. The other cause of nasal bleeding is a hematoma in the sinus cavity and many of these require surgery.
The other significant type of nasal discharge is a purulent discharge. A purulent discharge is yellow or green pus and usually indicates an infectious process. Some of these infections are just upper respiratory infections in the nasal cavity and will respond well to antibiotics. However, many of these infections are located in either the guttural pouches or the sinus cavities. If your horse has a discharge that does not respond to antibiotics, it is critical for your vet to place a scope in the nasal cavity and upper airway to determine the source of the discharge. The guttural pouch is a structure unique to horses and is a small pouch with an opening just in front of the horse's throat. This structure can become infected and is a common site of infection in horses with strangles. The difficulty with infections in this pouch is that oral or injectable antibiotics are rarely effective, and in many cases the infection must be flushed out with a catheter. The other source of a chronic nasal discharge is a sinus infection and like a guttural pouch infection, flushing out the sinus is usually required. The difficulty in this procedure is that to flush the sinus, a hole must be made in the bone of the face to insert a tube for flushing or a surgery must be performed to remove a flap of bone to examine the sinus. Sinus infections can be a primary infection or they can commonly occur as a result of dental disease. An infection in the mouth around the teeth can enter the sinus, so any horse with a sinus infection must have a thorough dental exam to determine if dental disease is the source of the infection.
If you have a horse that has consistent bleeding out of the nose, even if it is a small amount, be sure and call your veterinarian as an endoscopic exam is required to determine its source.