A structure in the horse’s respiratory system called the guttural pouch is unique to equine animals and a few other species. It is a pouch or pocket off of the respiratory tract in the horse’s throat area, adjacent to the Eustachian tube. Some people believe the function of these guttural pouches is to allow the arteries that carry blood to the brain to be cooled during intensive exercise because the pouch is lined by a thin membrane that covers the internal carotid artery. These pouches contain major arteries and nerves.
Multiple diseases can occur in the guttural pouch. The most common is a secondary infection after a strangles infection, which is bacterial. The pouch can fill with infectious material and the horse can continue to spread the infection to other horses even after the horse has no clinical signs. Treatment requires flushing the guttural pouch and packing it with antibiotics.
Another concern with the guttural pouch is a fungal infection called guttural pouch mycosis. Dr. Nathan Slovis indicates this infection can be a life-threatening disease as the internal carotid artery that I mentioned is only covered by a thin membrane. If the fungus destroys the membrane and artery, severe and even deadly bleeding can occur. The fungus can also affect some of the cranial nerves in the area and can lead to difficulty eating and swallowing. Treatment for the fungal infection usually requires surgery as treating this particular infection with antifungal medications are usually not effective. The best treatment is surgery in which a balloon is inserted in the artery to block the blood supply to the fungus. Without a blood supply, the fungus will die. So if your horse has a nasal discharge, especially if it is bloody, call your vet for an exam of the guttural pouches