Recurrent vestibular paroxysms associated with systemic hypertension in a dog

Abstract

A 9-year-old 19.7-kg (43.3-lb) spayed female Australian Shepherd was examined for an increase in frequency of episodic neurologic signs, often occurring upon exercise. Between episodes of neurologic signs, the dog was considered clinically normal on the basis of findings on physical and neurologic examinations. An episode of ataxia with central vestibular signs was induced by exercising the patient in the hospital. All clinicopathologic values were within reference ranges, as were findings on magnetic resonance imaging of the brain and peripheral vestibular system. Systolic blood pressures of 180 to 200 mm Hg were recorded, and systemic hypertension was diagnosed. While the dog received amlodipine and enalapril, blood pressure returned to within reference range, and episodes of neurologic signs no longer occurred. When clinical signs later recurred, systolic blood pressure was again found to be high. Following an increase in medication dosage, blood pressure normalized, and only 4 further episodes of neurologic signs were observed during a follow-up period totaling 30 months. Transient ischemic attack is a common diagnosis in humans but has not been described for dogs. In humans, it is defined as focal brain dysfunction caused by vascular disease that resolves completely in less than 24 hours and is often recurrent. Systemic hypertension is one of the most common preexisting conditions. We propose that the dog in the present report had clinical signs and diagnostic test results supportive of a diagnosis of transient ischemic attack.