Otitis Media and Otitis Interna in Dogs
Otitis media refers to an inflammation of the dog's middle ear, while otitis interna refers to an inflammation of the inner ear, both of which are commonly caused by bacterial infection. Long-eared dog breeds with excessive hair and non-erect outer ears, such as the Cocker Spaniel, Labrador Retriever and Springer Spaniel, are believed to be more susceptible to canine ear infections.
Cats are also prone to these two conditions. If you would like to learn more about how this disease affects cats, please visit this page in the PetMD health library.
Symptoms and Types of Ear Infections in Dogs
The symptoms apparent in cases of otitis media or interna are largely dependent on how severe and extensive the infection is. Signs may range from no visible symptoms whatsoever, to apparent nervous system involvement. If symptoms appear, they may include pain when opening the mouth, reluctance to chew, shaking the head, pawing at the affected ear, tilting the head, leaning to the side of the affected ear, and an altered sense of balance (known as vestibular deficits). If both ears are affected by inflammation, further symptoms may include wide swinging movements of the head, wobbly uncoordinated body movement, and deafness.
Additional symptoms may include vomiting and nausea, unequally sized pupils, redness of the ears, ear discharge, a grey bulging eardrum (known as tympanic membrane), and in severe cases, signs associated with nervous system damage such as facial nerve damage (e.g. inability to blink, or paralysis).
Causes of Ear Infections in Dogs
Bacteria are the primary disease-causing agents that lead to infection and consequent inflammation of the middle or inner ear. Other possible disease-causing agents include yeasts such as Malassezia, fungi such as Aspergillus, and ear mites which increase the likelihood of bacterial infection. Alternate causes include trauma to the body, such as from a car accident, the presence of tumors or polyps in the ear, and the presence of foreign objects in the ear.
Diagnosing Dog Ear Infections
One primary diagnostic procedure in cases of inner and middle ear inflammation is myringotomy, a technique in which a spinal needle is inserted into the air and the ear drum membrane to extract middle ear fluid for microscopal examination. This can help determine any infectious presences, such as bacteria or fungi. Other tests may include an analysis of cerebrospinal fluid in the cranium, in which the brain essentially floats, urine analysis, blood tests, and computed tomography (CT) or magnetic resonance imaging (MRI) scans.