Otitis Media and Interna in Dogs
Inflammation of the middle ear structures (otitis media) is usually caused by an extension of infection from the external ear canal or by penetration of the eardrum by a foreign object. The spread of infection through the bloodstream to these areas is also possible, but it is rare. Inflammation of the middle ear may lead to inflammation of the inner ear structures (otitis interna). This can in turn lead to loss of balance and deafness.
The signs of otitis media may be similar to those of otitis externa. Head shaking, ear scratching, rubbing the affected ear on the floor, and rotating the head toward the affected side are often noted. The ear is usually painful and may have a discharge and inflammatory changes in the ear canal. Inflammation of the outer ear (otitis externa) that recurs may be another sign.
Because the facial and sympathetic nerves travel through the middle ear, facial nerve paralysis, constriction of the pupil of the eye, drooping of the eyelid, sinking of the eyeball into the orbital cavity, and protrusion of the third eyelid may occur on the same side as the affected ear. If otitis interna occurs at the same time, head tilt toward the affected side will be more obvious. Additionally, an animal with inflammation of the inner ear may have an overall lack of coordination severe enough to cause difficulty in rising and walking. An involuntary rhythmic movement of the eyes from side to side (called nystagmus) may also be seen with inflammation of the inner ear. If the inflammation spreads to the brain, neurologic signs can be seen.
Your veterinarian may diagnose otitis media when the eardrum is ruptured, either by a foreign object or longterm inflammation. It is difficult to diagnose if the eardrum is not ruptured, which is the case more than 70% of the time. Otitis media has been found to be present in more than half of the dogs with longterm, recurrent inflammation of the external ear. Fluid in the middle ear or hardening and fibrous overgrowth of the round bone behind the ear may be detected through x-rays, computerized tomography (CT scan), or magnetic resonance imaging (MRI).
Otitis interna may be diagnosed based on similar signs with the addition of loss of balance. Examination using an otoscope and x-rays of the round bone behind the ear may confirm the presence of simultaneous middle and inner ear inflammation.
Because of the possibility of hearing loss and damage to the organ of balance (vestibular apparatus), longterm antibiotics given by mouth or injection may be prescribed by your veterinarian to treat otitis media or interna. Treatment may last 3 to 6 weeks. If the eardrum is ruptured, your veterinarian will carefully clean the middle ear. Small perforations of the eardrum usually heal in 2 to 3 weeks. Any inflammation of the external ear canal will be treated at the same time. Additionally, anti-inflammatory medications may be prescribed during the first week of treatment to decrease pain and inflammatory changes in nearby nerves.
If your dog’s external ear is clean and normal, but the eardrum is bulging or discolored, your veterinarian may perforate the eardrum to relieve the pressure (and thus the pain) within the middle ear, to permit removal of the inflammatory discharge, and to allow for culture of the fluid for diagnosis and treatment. Antibiotics given by mouth or injection may be prescribed for 3 to 6 weeks if inflammation of the inner ear exists. In longterm otitis media, surgery may be necessary to allow for drainage and adequate resolution of the infection.
Otitis media with an intact eardrum usually responds well to antibiotic therapy. However, if longterm inflammation of the inner ear exists and the eardrum is ruptured, the chances of successful treatment are reduced. If local nerve problems develop, they may continue even after the infection has been cleared. Inflammation of the inner ear usually responds well to longterm antibiotic therapy, but some neurologic problems (for example, lack of coordination, head tilt, deafness, drooping lips, or inability to blink) may persist for life. Animals recovering from inflammation of the inner ear should be given adequate time to adapt to any persistent nerve-related signs.
The sooner animals can be treated, the better the prospect is for a good outcome. If you notice any of the signs indicating a possible infection or inflammation in your pet’s ears or if you notice any changes in your dog’s normal head position or movement, a checkup should be scheduled promptly.
Also see professional content regarding otitis media and interna.