Diseases of the inner ear are characterized by labyrinthitis, or dizziness. The labyrinth is part of a complex organ of balance composed of the semicircular canals, the utricle, and saccule. The labyrinth is like a gyroscope. Its purpose is to synchronize eye movements and maintain posture, balance, and coordination. The most common cause of labyrinthitis is inner ear infection.
A dog with labyrinthitis will often assume an abnormal posture, with her head tilted down on the affected side. Dizziness, lack of coordination, and loss of balance are evident. The dog circles and leans toward the affected side and may exhibit rapid jerking movements of the eyeballs, a condition called nystagmus. Some dogs vomit.
Idiopathic vestibular syndrome is a disease of unknown cause that affects middle-aged and older dogs. It is the second most common cause of labyrinthitis. The onset is sudden. The dizziness, staggering, and vomiting can be incapacitating. Vomiting may last for several days, in which case the dog may require intravenous fluids. Signs peak in 24 hours, but some degree of imbalance persists for three to six weeks. Recovery occurs in almost all cases. After recovery, some dogs experience a slight but permanent head tilt.
The prolonged administration of aminoglycoside and neomycin antibiotics can produce labyrinthitis, as well as deafness. Most ear preparations are capable of causing labyrinthitis and ear damage if they make contact with the sensitive structures of the inner ear. This is why the ears should never be flushed or medicated without first making sure that the eardrums are intact.
Other causes of labyrinthitis include head trauma, brain tumor, poisoning, and drug intoxication. Suspect one of these if your dog develops labyrinthitis without having had a prior ear infection.
Treatment: The underlying cause must be diagnosed and treated. Supportive care and medications to relieve the symptoms assist in recovery.