Bradycardia associated with meningioma in a dog.

Clinical signs of bradycardia and syncope, associated with intracranial meningioma, were observed in a 4-year-old female Irish Setter. Electrocardiographic abnormalities confirming bradycardia and suggestive of sinoatrial arrest were demonstrated. Return to a normal heart rate and sinus rhythm after administration of atropine IV indicated that increased vagal tone was responsible for the observed abnormalities. Neither glycopyrrolate nor propantheline bromide therapy was successful in controlling bradycardia and syncope. Necropsy findings included the demonstration of a 3 X 2 X 2-cm mass on the ventral aspect of the right half of the brain. This mass covered half of the mammillary body and extended as a thick reddish brown membrane extending over the piriform lobe of the cerebrum, optic chiasm, and longitudinal fissure. Histologically, the mass was identified as a meningotheliomatous meningioma.