Labyrinthitis is an inflammation of the labyrinth in the inner ear of dogs. The labyrinth is a complex system of canals in the inner ear. It consists of the vestibule, semicircular canals and the cochlea. The vestibule and semicircular canals help the dog to maintain posture, balance and coordination. The cochlea is a part of auditory, or hearing, function.
Causes of Labyrinthitis in Dogs
The most common cause of labyrinthitis is an infection and inflammation of inner ear, also called otitis interna. An infection of the inner ear is often preceded by infection of the outer and middle ear. Another common cause of labyrinthitis is idiopathic vestibular syndrome. This disease has no known cause and affects adult dogs.
Some treatments of the ear can cause damage resulting in laryrinthitis. Antibiotics that are administered for long periods can damage the auditory and vestibular nerves. Ear preparations for medical treatments or cleaning of the ear can also cause damage if they come in contact with sensitive structures of the internal ear.
Dogs that have no history of prior ear infections or treatments can also suffer labyrinthitis. This can occur if the dog has recently experienced injuries due to:
-
Head trauma
-
Brain tumors
-
Poisoning
-
Drug intoxication
Symptoms of Labyrinthitis in Dogs
Many dogs will show symptoms of labyrinthitis and an associated infection of the ear. Symptoms may include:
-
Ear pain
-
Ear discharge
-
Abnormal posture
-
Head tilt (down, on affected side)
-
Dizziness
-
Lack of coordination
-
Loss of balance
-
Circling and leaning (towards affected side)
-
Difficulty rising
-
Nystagmus (rapid movements of eyeballs in a horizontal or rotating motion)
-
Vomiting
-
Deafness
Dogs that experience labyrinthitis due to idiopathic vestibular syndrome will exhibit a sudden onset of dizziness, staggering and vomiting. The dog may be temporarily incapacitated but recovery occurs in all cases. This condition may result in a permanent tilt of the head.
Diagnosis of Labyrinthitis in Dogs
Labyrinthitis is suspected if the dog is already suffering from severe or chronic infection of the outer, middle or inner ear. A veterinarian will examine the ear with an otoscope to confirm the diagnosis. The tympanic membrane, or eardrum, may be ruptured or appear bulging and discolored. A CT scan may be recommended to determine if fluid is present in the tympanic cavity. Bacterial cultures may be obtained for laboratory testing and to determine the appropriate course of treatment.
Treatment of Labyrinthitis in Dogs
The effectiveness of therapy depends on how quickly the condition is diagnosed and treated. If the dog has displayed signs of outer or middle ear infection and is given persistent treatment, otitis interna and the associated labyrinthitis can be prevented. A veterinarian will prescribe long term antibiotic therapy for up to 6 to 8 weeks. In cases where the eardrum is ruptured or medication must be administered to the inner ear, the veterinarian will recommend a careful cleaning of the inner ear that may require general anesthesia. Glucocorticoids may be prescribed for approximately the first week of treatment, to reduce inflammation.
If the veterinarian determines that the eardrum is bulging or discolored, a myringotomy may be recommended. In this procedure the tympanum is perforated to obtain fluid for bacterial culture tests, and to relieve pressure and pain. Treatment is usually effective to correct the condition but the dog may suffer permanent effects of incoordination, deafness or tilting of the head.