Vestibular Disease in Dogs
The vestibular system is primarily responsible for keeping the head and body in the correct orientation with respect to gravity.

This system will alert the brain if we are standing, sitting, lying down, falling, spinning in circles, and keeps the body balanced. The vestibular system is comprised of nerves that start in the brain and continue to the inner ear. The sensors in the inner ear are responsible for informing the brain about any movement. Vestibular disease affects the ability of the brain to recognize abnormal body positions and also affects the brain's ability to correct these abnormalities.

Disorders of the vestibular system are divided into central vestibular disease and peripheral vestibular disease.

Central vestibular disease occurs due to an abnormality within the brain. Peripheral vestibular disease occurs due to an abnormality within the nerves of the inner ear.

Most cases of vestibular disease are peripheral and no known cause is determined. These are referred to as idiopathic.

Vestibular disease typically affects older dogs with an average age of 12 to 13 years.

Animal afflicted with vestibular disease become suddenly very dizzy and the symptoms can be very drastic and frightening to the owner.

What to Watch For


Falling

Incoordination

Head tilt to one side or another

Circling

Rolling

Eyes continually drifting side to side or up and down

Stumbling or drunken walking.

Diagnosis

Vestibular disease can affect an animal very suddenly. Due to the signs of head tilt, circling and staggering, many owners feel their pet has had a stroke. Fortunately, strokes are rare in animals.

Veterinary care should include diagnostic tests and subsequent treatment recommendations. Other disorders that result in signs similar to vestibular disease include:


Inner ear infections

Thiamine deficiency

Head trauma

Metronidazole (antibiotic) toxicity

Middle ear polyps

Middle ear cancer

Diagnostic tests are needed to determine the presence of an underlying disease or cause for the vestibular disorder and to differentiate vestibular disease from other disorder affecting the balance system of the body. Vestibular disease, for which an underlying cause cannot be determined after thorough diagnostic evaluation, is called idiopathic.

Tests may include:

Your veterinarian will take a complete medical history and perform a thorough physical examination including a complete neurologic examination and complete examination of the ear canal.

Blood tests may be recommended to determine your pet's general health and the presence of an underlying disease that may be causing the vestibular disease. Recommended blood tests may include:


A complete blood count (CBC or hemogram)

Serum biochemistry tests to evaluate blood glucose, liver and kidney function and electrolytes

Urinalysis

Other diagnostic tests may be recommended based on the results of the history, physical examination and initial laboratory tests such as spinal tap, CT, MRI or skull x-rays.

Treatment

Results of the history, physical examination and initial laboratory tests will determine the need for further diagnostic tests and will help determine the appropriate treatment for your pet's vestibular disorder. Treatment will be dictated by the underlying cause. When possible, the specific underlying cause of the vestibular disorder should be treated. Idiopathic peripheral vestibular disease generally slowly improves over the course of one to two weeks and little treatment is needed.

Due to dizziness, some pets benefit from motion sickness medication such as meclizine or diphenhydramine.

For central vestibular disease, treatment is specific for the cause of the disease.

Home Care and Prevention

Call your veterinarian promptly if your pet is showing signs of vestibular disease. This is a frightening experience for your pet so speak calmly and soothingly. Make sure he does not injure himself. Avoid steps and watch for worsening of signs such as vomiting or seizures.

For idiopathic vestibular disease, there is no known preventative since the cause is not known. For other causes, avoid traumatic incidence by keeping your dog on a leash or in an enclosed area. Keep your pet vaccinated and avoid exposure to poisons or toxins.

Section: Information In-depth

Peripheral vestibular disease primarily affects older dogs, age 12 to 13 years of age.

Typically, peripheral vestibular disease does not have a known cause. Many resolve and slowly improve over one to two weeks. The involuntary drifting of the eyes usually goes away in the first few days. Your pet may have a permanent head tilt, but most pets accommodate and do well.

Other diseases that have signs similar to peripheral vestibular disease are:



Inner ear infections

Low thyroid function

Trauma of the inner or middle ear

Cancer of the middle ear

A thorough ear examination will help determine if the cause of the symptoms is due to peripheral vestibular disease or another cause. Unfortunately, there are no specific tests that will confirm peripheral vestibular disease. If the animal is showing the typical signs and all other causes of these signs have been ruled out, the animal is diagnosed with peripheral vestibular disease.

Central peripheral disease also primarily affects older dogs. Most cases of central peripheral disease are due to tumors within the brain affecting the vestibular nerve.

Other diseases that mimic the signs of central peripheral disease include:


Thiamine deficiency

Head trauma

Metronidazole toxicity

Viruses such as distemper, herpes, parainfluenza, rabies

Bacterial brain infections

Rickettsial infections such as Rocky Mountain spotted fever, ehrlichia, Lyme

Leptospirosis

Fungal infections such as blastomycosis, histomycosis, cryptomycosis, coccidioidomycosis, aspergillosis

Protozoal infections such as toxoplasmosis, neosporosis

Thorough examination, blood tests, CSF tap, and possibly CT or MRI are necessary to determine the cause of central vestibular signs.

Section: Veterinary Care In-depth

Initially differentiating between peripheral and central vestibular disease can be difficult. Both are characterized by a significant loss of balance with head tilt, leaning, falling, involuntary eye movements (nystagmus) and staggering. There are a few clues that can lead toward a diagnosis of central vs. peripheral vestibular disease.

The eye movements can help differentiate between central and peripheral. The involuntary eye movement is referred to as nystagmus. The eyes can go side to side (horizontal), up and down (vertical) or rotary (circular).

Peripheral vestibular disease



Rolling is seldom seen

Horizontal or rotary nystagmus – not vertical

Facial paralysis may be seen with drooping of one side of the face

No mental changes noted

No body weakness

No difficulty in placement of feet

Central vestibular disease


More tendency to roll

Horizontal, rotary and vertical nystagmus

When the animal is placed on his back, the nystagmus will change. This is referred to as positional nystagmus. In peripheral cases, the nystagmus does not change when the animal is placed on his back.

Mental depression

Possible head tremor

Weakened jaw

Poor foot placement

Excessive staggering or stumbling

Diagnosis

Diagnosing central vs. peripheral vestibular disease can be challenging. Even with appropriate signs supportive of peripheral or central disease, additional tests are necessary to confirm the diagnosis. Unfortunately, the best diagnostic test is CT or MRI. Due to expense, this test is not available to everyone.

The importance of determining central vs. peripheral disease is to provide proper treatment and prepare for potential future problems. Peripheral disease usually resolves and the animal returns to normal. Central disease is more devastating and the animal may never recover, even with aggressive treatment.

Initial diagnostics include blood tests. These test will help determine the overall health of the animal and makes sure the animal is able to tolerate additional tests. A spinal tap is helpful to rule out infections. CT or MRI, advanced x-rays which look within the brain, can help determine if a tumor or brain abnormality is present. If all these tests are negative, the animal is diagnosed with peripheral vestibular disease.

Treatment

Initial treatment of vestibular disease, both peripheral and central, is aimed at reducing the symptoms associated with a loss of balance. Some animals are able to eat and drink, show no signs of nausea and do not need medication. Those that have no appetite or vomit may require motion sickness medications. Commonly prescribed medications include:


Diphenhydramine 1-2 mg per kg (1 mg per pound) twice daily

Meclizine 1-2 mg per kg (05-1 mg per pound) twice daily

These medications can help reduce the nausea associated with motion sickness and dizziness. Those animals with central peripheral disease will need additional treatments aimed at correcting the underlying cause.

Most diagnosed cases of central vestibular disease are caused by a tumor within the brain. Treatment for brain tumors include surgery, radiation therapy and, sometimes, chemotherapy. The type of tumor will determine which treatment, if any, is recommended.

Section: Follow-up

Careful monitoring is necessary during recovery from vestibular disease. Administer all prescribed medications and make sure your pet is slowly improving. Any relapse or worsening of signs should prompt an examination by your veterinarian.

For those animals with peripheral vestibular disease, full recovery is expected within two weeks. A residual head tilt may be permanent.

Those animals with central vestibular disease may not fully recover. Follow up is based on the extent of treatment. Patients undergoing surgery or radiation will need extensive follow up care with scheduled veterinary examinations and may need lifetime medication.