Vestibular disease in dogs

Overview

Inner ear, nerve and brain

The vestibular system helps dogs stay upright and coordinate movement. Its peripheral part includes the inner ear balance organs and vestibular nerve, which carries signals to the brain. Central balance structures lie in the brainstem and cerebellum. Head tilt, staggering and involuntary eye movements can occur with disorders in either part.

Vestibular syndrome has several possible causes. If no cause is found and findings fit a peripheral disorder, it is called idiopathic vestibular syndrome.

The inner ear balance organ includes the vestibule and semicircular canals, which inner ear inflammation can affect.

Causes

Peripheral disorders

Common causes are middle or inner ear disease and idiopathic syndrome. Persistent outer ear inflammation can spread through the eardrum into the middle ear. Untreated middle ear infection can spread to inner ear balance organs. Some medicines can damage inner ear structures. Hypothyroidism can sometimes be associated with vestibular nerve dysfunction.

Among 188 dogs with peripheral disease undergoing MRI, 128 had idiopathic syndrome. Middle or inner ear infection occurred in 49. Seven, or 4%, had hypothyroidism. Two were considered to have congenital disease.

Brainstem and cerebellar disease

Tumours in these areas can cause staggering similar to inner ear disease. A blocked vessel causing cerebellar infarction can produce sudden balance problems. Brain and meningeal inflammation can also cause vestibular signs.

Risk factors

Idiopathic syndrome particularly affects older dogs. UK primary care records identified vestibular disease in eight per 10,000 dogs during 2016. Among dogs aged at least nine, prevalence was 36 per 10,000. Median age at first diagnosis was 12.68 years. Compared with crossbreeds, French Bulldogs had a diagnosis odds ratio of 9.25. The corresponding ratio for Cavalier King Charles Spaniels was 3.56.

Middle and inner ear infections may account for a greater proportion of peripheral disorders in young dogs than older dogs. Rapidly recurring outer ear inflammation after successful treatment can reflect untreated middle ear infection. Medication history matters because metronidazole toxicity, for example, can cause vestibular signs.

Typical symptoms

Signs can develop within an hour, changing normal movement into severe staggering.

• Head tilt with one ear clearly lower.
• Leaning or falling to one side.
• Circling or rolling on the ground.
• A wide stance to maintain balance.
• Rapid involuntary eye movements, called nystagmus.
• Abnormal eye position when head position changes.
• Nausea and vomiting associated with dizziness.

Nauseous dogs may lick their lips or drool without vomiting.

Idiopathic signs are often worst during the first 24–48 hours. UK primary care records noted head tilt in 530 of 759 dogs, or 69.82%. Nystagmus occurred in 516, or 67.98%. An unsteady, poorly coordinated gait occurred in 489, or 64.42%.

Difficulty balancing may make dogs refuse to move. Nausea may stop them eating. Inner ear inflammation can cause horizontal or rotary nystagmus.

Complications and consequences

Dehydration, injuries and residual signs

Severely unsteady dogs can be injured by falls or collisions with furniture. Inability to drink normally can require hospital fluids. Mild head tilt can persist despite otherwise restored movement. Inner ear inflammation can impair hearing through effects on the vestibulocochlear nerve. In follow-up, peripheral disease recurred in 26 dogs, or 17.6%, during the following 12 months.

Inner ear infection spreading to the brain can cause meningitis. Affected dogs may become dull and feverish.

Middle ear disease-associated facial paralysis can alter muzzle or lip position. Middle ear disease can also cause dry eye and corneal ulceration.

Diagnosis at the vet

Neurological examination

The vet observes gait, head position and eye movements to localise dysfunction. General examination also assesses pain, as idiopathic syndrome is usually painless. Altered alertness can suggest brain involvement. Delayed correction of an abnormally positioned paw can indicate central disease. Vertical nystagmus alongside other findings can suggest brainstem or cerebellar injury. Facial nerve dysfunction can accompany peripheral disease because this nerve runs near the vestibular nerve.

Ear examination and imaging

Otoscopy can identify eardrum bulging, rupture or other abnormalities. The eardrum can appear intact despite middle ear infection. MRI can examine inner ears and brain when location or cause remains unclear. CT can reveal middle ear fluid, for example. Fluid findings need interpretation alongside signs because dogs without ear symptoms can also have fluid. Suspected bacterial middle ear infection can be sampled directly for culture.

Imaging was normal in 83 of the 128 idiopathic dogs, or 65%. Contrast enhancement affected only the facial nerve in 30, or 23%.

Blood tests and further investigations

Cerebrospinal fluid sampling may be needed if a more serious cause is suspected. Brainstem auditory evoked responses can investigate whether sound signals reach the brainstem when hearing is impaired. Blood tests can investigate hypothyroidism. Blood pressure may be measured when investigating suspected cerebrovascular disease and predisposing conditions.

Treatment

Fluids and nausea control

Idiopathic syndrome treatment relieves symptoms and supports recovery. Medication can treat dizziness-associated nausea or vomiting. Hospital care may be needed if eating or moving independently is impossible. A medicine controlling vomiting may have limited effects on nausea, so behaviour also informs assessment.

A randomised comparison investigated nausea treatment in 14 dogs with vestibular syndrome. Nausea signs were monitored for four hours. Signs were observed to resolve one hour after ondansetron administration in treated dogs.

Four of the 14 dogs had also vomited before medication. Behaviour was used to assess nausea even without vomiting.

Treating the underlying cause

For bacterial middle or inner ear infection, antibiotic selection ideally follows culture. Surgical drainage of the middle ear cavity is sometimes needed. Inner ear infection treatment and recovery can take months. Cerebral infarction care supports the dog and manages any underlying disease.

Recovery time

Initial idiopathic improvement often appears within two to three days. Head position and gait can gradually improve over seven to 10 days. Full recovery is possible within one to two weeks. Many recover completely within two to three weeks. Recovery can also take two to four weeks. Failure to improve as expected or deterioration can prompt further investigations.

In idiopathic peripheral disease follow-up, 47 of 94 dogs with available recovery data, or 50%, recovered completely. Head tilt remained in 25, or 27%. Facial paralysis persisted in 28, or 30%. Another episode occurred in 19 of 85 idiopathic dogs with recurrence information, or 22%.

Prevention

Unknown cause prevents targeted prevention of idiopathic syndrome. Early treatment of recurrent outer ear inflammation can reduce chronic disease. Persistent outer ear inflammation warrants investigation of middle ear involvement. Follow-up confirms resolution. Do not use leftover ear drops without veterinary advice: some can damage balance organs if the eardrum is ruptured.

Treating underlying causes helps prevent recurrent ear inflammation.

Important for dog owners

Keep an unsteady dog at floor level in a small, softly bounded area to prevent fall injuries. Put food and water near the bed once independent eating and drinking are possible. If your dog can take steps, a broad towel beneath the abdomen can provide support for brief toilet trips. Tell the vet when staggering started and about previous similar episodes. Contact the vet again for worsening signs or inability to drink.

If walking outside is unsafe, carrying may be needed for short transfers. Supporting a large dog outdoors may need two people. Report current ear drops if balance problems began during ear treatment.

Frequently asked questions

Does a sudden head tilt mean a stroke?

It can arise from inner ear or brain disease. Cerebellar infarction can resemble idiopathic syndrome. Neurological examination and, when needed, brain and ear imaging help distinguish causes.

When does an older dog's vestibular syndrome start improving?

Many dogs with idiopathic syndrome improve clearly within two to three days. Head position and gait can take seven to 10 days to settle. Deterioration prompts reassessment of investigation needs.

Can dogs feel nauseous without vomiting?

Yes: lip licking, drooling and restlessness can indicate nausea. Report food refusal or behavioural changes during dizziness. The vet can prescribe medication for associated nausea.

Can head tilt be permanent?

Some dogs retain mild tilt or unsteadiness after other signs resolve. Many adapt and move well. Renewed deterioration in balance needs veterinary assessment.

Does every dog need MRI?

Tests are selected according to signs and neurological findings. MRI may be considered if improvement does not begin as expected, for example. It helps examine the inner ear when more diagnostic information is needed.