Vestibular Disease in Dogs
Strokes are rare in dogs. A stroke, or cerebrovascular accident, occurs when normal blood flow to the brain is disrupted, resulting in neurological signs that depend on the area of the brain that is affected. It occurs suddenly, and the signs produced do not worsen over time.
Signs of a cerebrovascular accident may be focal, such as circling and head tilt, or generalised, resulting in seizures, weakness, or coma. A stroke is due to occlusion of a blood vessel by tumour cells or emboli. An embolus is a blockage that originates elsewhere in the body and lodges in a cerebral vessel. The blockage may be blood clots (such as after surgery), air, or fat.
Vestibular Disease
Much more common than strokes is Vestibular Disease which produces signs that can look like a stroke.
The vestibular system is responsible for maintaining normal balance and disease of the system affects the head and body’s ability to orient themselves with respect to gravity.
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, such as a tumour, blood clot or injury. 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.
Old Dog Vestibular Disease
Peripheral vestibular disease is not an uncommon problem in older dogs, and is characterised by a sudden onset of signs including head tilt, wobbliness, falling or inability to stand due to loss of balance. Disorientation may be severe. Nystagmus (flickering of the eyes) is present and some dogs have transient nausea, vomiting and anorexia.
Since the cause of this problem is unknown it is termed ‘idiopathic’. It is diagnosed by eliminating other causes of peripheral vestibular disease such as inner ear infection, and the condition improves over time (usually a few weeks although in some cases the head tilt is permanent). Some dogs benefit from motion sickness medication to treat nausea and vomiting.
