Head Tilt in Dogs (Vestibular Signs)
Dr. John McDonnell
Vestibular signs, a disturbance of our sense of balance, can be seen as a head tilt as well as other alarming signs such as falling, rolling, continuous circling and nystagmus (rhythmical, jerky movements of the eyes). Other signs of vestibular disease include nausea, vomiting and lack of appetite. Otitis media-interna. Infection of the middle or inner ear caused by bacteria, mites or even foreign bodies such as grass seeds is the most common cause for vestibular signs. Infections may initially affect only the outer ear, but if this inflammation ascends into the middle and inner ear, vestibular signs may be seen.
The vestibular apparatus in the inner ear maintains our sense of balance. It is a delicate sense organ that is completely surrounded by an extremely hard bone (petrous temporal bone) at the base of the skull. The inner ear has intimate connection with the brain via the auditory and vestibular nerves. The inner ear is also associated with the middle and external ear.
Since the inner ear is intimately associated with the middle and external ear, signs associated with ear infections such as malodorous discharge from the ear, scratching or shaking the ear and pain or redness of the ear may be seen.
A head tilt is usually described according to the side of the animal's head that turns down. Animals typically fall or roll towards the same direction as the head tilt. Nystagmus (an involuntary rhythmic movement of the eye) is only a symptom of vestibular disease and does not indicate severity of the disease.
Since the middle and inner ear are located close to the temporal mandibular joint (jaw), there may be pain associated with chewing or opening the mouth. These animals may even yelp out in pain while they are yawning.
The most common cause of vestibular signs is ear infections. Damage to the inner ear structures or the brain itself may cause vestibular signs. Vestibular signs indicate either a problem in your pet's inner ear or brain. It is very important for your veterinarian to determine quickly whether the cause of your pet's vestibular signs are due to disease of the inner ear (peripheral vestibular disease) or to disease of the brain (central vestibular disease). The choice of different diagnostic tools and the prognosis depend on the suspected location of the problem. In general, peripheral vestibular disease has a better prognosis than central vestibular disease.
There are many causes for head tilt. Some of these include:
Idiopathic (unknown cause). In older dogs this is the second most common cause of peripheral vestibular signs. This disease (Geriatric Canine Idiopathic Vestibular Syndrome) can cause catastrophic vestibular signs acutely. The dog may have problems walking and standing, and may also experience nystagmus and vomiting. Pets can improve with little treatment, although other causes such as ear infections and brain tumors should be ruled out.
Ototoxic drugs can damage the ear resulting in vestibular disease. Not all animals have trouble with these particular drugs and medications; some of the most common ear medications contain some of these drugs. If your animal is being treated with one of these medications, it may be due to the administration of the drug. To determine if your pet's symptoms are caused by the drugs, contact your veterinarian and discuss this possibility. The list of potential ototoxic agents include:
Antibiotics such as gentamycin, streptomycin, amikacin, neomycin, kanamycin, erythromycin, chloramphinocol, polymyxin B or metronidazole.
Some ear cleaners including ethanol (alcohol), chlorhexidine, idodine containing medications, centrimide and benalkonium chloride.
Diuretics such as furosemide, ethancrynic acid and bumetanide.
Antineoplastic (cancer fighting) medications such as nitrosoureas (CCNU and BCNU) and cisplatin.
Some of these drugs can also cause deafness.
Other causes of head tilt include:
Head trauma can cause vestibular signs that may resolve with time.
Endocrine diseases such as hypothyoidism can cause vestibular signs.
Encephalitis affecting the area of the brain responsible for maintaining the sense of balance can cause vestibular signs. Some of the inflammatory causes for vestibular signs include canine distemper virus, Rocky Mountain spotted fever, ehrlichiosis, cryptococcosis, blastomycosis, coccidiomycosis, toxoplasmosis, neosporosis and granulomatous meningoencephalomyelitis.
Neoplasia (cancer or tumors) in older pets affecting either the ear or brain can cause vestibular signs. Some tumors can be removed successfully after diagnosis using CT or MRI.