Tympanic Membrane Rupture and Middle Ear Infection
My dog has been diagnosed with a middle ear infection. What is it?
The tympanic membrane or “eardrum” is a thin membrane that separates the outer ear canal from the middle and inner ear. The middle ear contains the three tiniest bones in the body, the malleus, incus and stapes, more commonly referred to as the “hammer, anvil and stirrup.” The Eustachian tubes are also located in the middle ear. If the eardrum is perforated or “tears,” bacteria and fungi from the outer ear canal may enter the sensitive middle ear resulting in otitis media or middle ear infection.
Middle ear infections are considered serious and aggressive treatment is often warranted.
What causes a ruptured eardrum?
A ruptured eardrum can be the result of trauma, infection, exposure to toxins, sudden severe changes in atmospheric pressure, very loud noises and foreign objects.
How can I tell if my dog has ruptured its eardrum or has a middle ear infection?
Most cases of ruptured eardrum and middle ear infection will be identified by your veterinarian. Symptoms include discharge from the ear (often thick and “pus-like” or bloody), sudden hearing loss, red and inflamed ear canal, pain when touching the ear, a head tilt, stumbling and incoordination and darting of the eyes back-and-forth (nystagmus). Facial nerve paralysis and drooping of one side of the face and mouth, inability to blink or a completely closed eyelid may occur in some cases. Middle ear infections are often accompanied by inner ear infections and disruptions of balance and equilibrium.
A dog that is tilting his head or experiencing any pain around the ears should be taken seriously.
A thorough ear examination, sometimes requiring sedation or anesthesia, is necessary to diagnose a ruptured eardrum. Many pets will require warm saline flushes. A classic test is to look for tiny air bubbles that form deep in the ear canal when the pet breathes. Another common test is to infuse a special dye, fluorescein, into the ear canal. If it escapes and exits through the nose, the eardrum is ruptured.
A special test called a myringotomy is usually performed in cases of middle ear infections. A myringotomy involves obtaining a sterile sample of the fluid within the middle ear for culture and analysis. A myringotomy is performed under sedation or anesthesia and is usually part of the thorough ear examination. Your veterinarian will discuss whether or not this diagnostic test is necessary for your pet.
Skull radiographs are often helpful in determining the severity of a middle ear infection. CT and MRI scans are also recommended in some cases and provide certain diagnostic advantages.
How is it treated?
A thorough ear flushing, usually under sedation or anesthesia is required in most cases. Your veterinarian will use appropriate medications and flushing solutions based on your pet’s specific condition. Oral antibiotics and antifungal medications are used in many cases. In addition, systemic corticosteroids (“steroids”) are beneficial in pets that have severe inflammation and pain. Some patients will require surgery. In these cases, your veterinarian will discuss with you the reasons for a surgical procedure, risks involved and expected outcomes. Surgery is typically reserved for cases thought to have severe, irreversible changes of the outer ear with concurrent middle ear infection.
What is the prognosis?
The majority of patients heal without significant complications within three to six weeks. Most ruptured eardrums heal without surgery within three to five weeks. Middle ear infections often require oral antibiotics or antifungal medications for four to six weeks. Most pets will require frequent recheck examinations and follow-up care to ensure the infection is resolving and the eardrum is healing properly. It is critical that you closely follow your veterinarian’s instructions to prevent serious complications or prolonged healing. In severe cases with nerve damage, there may be permanent changes in the face, lips, eyes or hearing loss. Your veterinarian will provide you with a more accurate prognosis based on your pet’s specific condition.