Vestibular Toxicity
Vestibular toxicity is also called peripheral vestibular disease, a toxic effect on the vestibule of the ear that afflicts dogs. Signs and symptoms are very dramatic and appear suddenly. The three main causes of vestibular toxicity are ear infections, medications placed in the ear and oral medications. Idiopathic cases are those with no known cause. Vestibular toxicity is treatable, and most dogs recover fully within two weeks of beginning treatment.
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Symptoms
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Onset of signs and symptoms is sudden and includes ataxia (loss of balance), nystagmus (constant shifting or rolling of eyes), dizziness, nausea, staggering, head tilt, stumbling, circling and rolling. Affected dogs frequently do not show signs of ear pain.
Ear Infections
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Infections of the middle and inner ear are a primary cause of vestibular toxicity. Unlike outer ear infections, they may not have any visible discharge or symptoms. They are caused by bacteria or fungi, and can come from an unnoticed or incompletely treated infection in the outer ear or mouth spreading inward or upward into the ear canal.
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Ear Medication Toxicity
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Another primary cause is introduction of medication into the dog's outer ear. This may be a toxic or allergic reaction to prescribed medication, but is more often from medication prescribed to a different animal or for a different illness. Human medications can also cause toxicity in dogs.
Oral Medication Toxicity
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Some vestibular toxicity is caused by oral medication. Metronidazole (trade name Flagyl) is the most common of oral medications. This type of toxicity is rare and usually occurs with prolonged or repeated exposure. Use should cease immediately at onset of symptoms.
Conditions with Similar Symptoms
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Pet owners and veterinarians can easily misdiagnose vestibular toxicity. It shares symptoms with many conditions, including benign and malignant tumors of the middle ear, inner ear and brain. Other conditions with similar symptoms are thiamine deficiency, head injury, thyroid disease and epilepsy. Severe bacterial and viral infections (such as rabies and distemper) resemble vestibular toxicity but, fortunately, most dogs in North America are vaccinated against these. Owners frequently misdiagnose vestibular toxicity as stroke, so one danger is unwarranted euthanasia.
Diagnosis
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Multiple tests may be needed for proper diagnosis. Basic tests are ear culture and analyses of blood, serum and urine. Idiopathic cases may need more aggressive diagnostics, including a magenetic resonance imaging exam.
Treatment
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Treatment depends on cause. Vestibular toxicity from ear infections is treated with antibiotics or antifungals. Cases caused by medication are treated by stopping the medication. The main dangers to dogs with this condition are nausea and secondary injury. Anti-nausea medication is usually necessary for the dog to continue eating and drinking. Feeding and watering may have to be done by hand. The dog will be distressed and disoriented, and must remain calm and protected from self-injury. A dog receiving treatment should recover within two weeks. If the condition progresses to vomiting or seizures, it is getting worse and vestibular toxicity may be a misdiagnosis.
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References
Resources
- Photo Credit dogs portrait image by Tomo Jesenicnik from Fotolia.com
