Canine Geriatric Vestibular Disease

Vestibular System

• The peripheral vestibular labyrinth contains tiny hairs that interact with nerve fibers. Information carried to the brain by these nerve fibers, along with information from other sensory systems such as visual, cognitive and visceral, combine in the brain to give the body a general sense of its location in space. This information is then sent to the balance control center in the brain. The brain uses this information to signal the muscles controlling the eyes and limbs, ultimately coordinating these muscles with the movement of the head. When vestibular disorders are present, these signals do not coordinate, and that leads to problems with balance, vision and muscle control.

Geriatric Vestibular Disease

• Geriatric vestibular disease, also known as idiopathic vestibular syndrome, is a common cause of vestibular problems in dogs. Most dogs affected are about 12 years old; however younger dogs may also be affected. This disease usually has a sudden onset, and many times is misdiagnosed as a stroke.

  Symptoms of idiopathic vestibular syndrome include ataxia, which is a lack of muscle coordination. Ataxia may cause the head and body to sway from side to side. Ataxia may also cause the dog to lean and fall to the side, or, in some cases, repeatedly roll onto one side. An abnormal tilting of the dogs head, simply called head-tilt, is also a common sign. Nystagmus, a rapid up and down or side to side motion of the eyes, is usually present as well. Some dogs will experience severe vomiting, which is caused by the feeling of dizziness associated with Nystagmus.

Diagnosis/Treatment

• There is no known cause for geriatric vestibular syndrome. The age of the dog and the rapid onset of symptoms is the first clue in the diagnosis. Many times, if your veterinarian suspects geriatric vestibular syndrome, treatment will be supportive during the initial 72 hours to determine if improvement begins. If your dog begins to show signs of improvement, no additional testing is usually necessary.

Prognosis

• Dogs usually begin to show improvement within 72 hours of the initial symptoms. Vomiting decreases, and the nystagmus and ataxia gradually begin to improve. Over the next several days, the head tilt is not as pronounced, and the ataxia begins to disappear. Most dogs return to normal within two to three weeks; however, a slight head tilt may remain. Most dogs do not experience repeat episodes. Dogs that are exposed to stressful situations may have a recurrence, however, they are usually mild and clear up quickly.

Other Vestibular Diseases

• In addition to geriatric vestibular syndrome, other vestibular diseases can affect dogs. These diseases can be broken into two categories: peripheral vestibular disease and central vestibular disease. These diseases present with the same symptoms as geriatric vestibular syndrome; however, they can usually be traced back to a cause. Causes of peripheral vestibular disease include middle or inner ear disease, trauma, congenital defect and an under active thyroid. Central vestibular disease can be caused by a brain hemorrhage, encephalitis, brain tumor, trauma or drug toxicity.