Despite Stroke Like Symptoms, A Dog’s Health Prognosis May Be Good

 Vestibular syndrome refers to a group of diseases that affect the balance system also known as vestibular system. Common signs of vestibular syndrome include loss of balance, falling, rolling over, abnormal flickering of the eyes and general wobbliness.

 Vestibular signs are commonly (and usually wrongly) referred to as a “stroke.” It should be noted that whilea vascular accident is a possible cause of vestibularsigns, it is a rare cause. Vascular disease (diseases of blood vessels outside the heart and brain), whilecommon in people, is unusual in pets.

What is the vestibular system?
The vestibular system controls balance and tries to prevent the animal falling over. Like the other senses, the balance system consists of sensors (deep inside the ear inner ear) and a specialized control center (at the back of the brain). Control of balance requires tiny changes in the position and movement of the body and the eyes depending on the position and movement of the head. The balance sensors detect the position of the head in space while an animal is standing at rest or when he is moving. The information on the position of the head is converted into electrical signals which are sent to the brain.

 The balance control center in the brain processes this information and sends messages to the rest of the body to keep the animal upright. Messages are also sent to the muscles controlling movement of the eyes to change the position of the eyes according to the position of the head.

Photo and Dog by Simply Spotted Photo. Pongo is currently being treated for Canine Vestibular syndrome. To see Pongo up and walking after 3 weeks of being diagnosed visit:

 THE SIGNS OF VESTIBULAR DISEASe
If there is trouble in the vestibular apparatus, then one may not properly perceive one’s orientation. To put it more simply, one won’t know which way is up, whether or not one is standing up straight or slanted, and one will feel very dizzy.

 The following are signs of vestibular disease:

 • Ataxia (lack of coordination without weakness or involuntary spasms - in other words, stumbling and staggering around)

 • Motion sickness

 • Nystagmus (back and forth or rotational eye movements. The movements will be slower in one direction. This is the side where the neurologic lesion is likely to be; however, nystagmus is named according
to the direction of the fast component - i.e. there may be left nystagmus but the lesion is probably on the right side of the vestibular apparatus.)

 • Circling (usually toward the side of the lesion.)

 • Head tilt (usually toward the side of the lesion).

 • Falling to one side (usually toward the side of the lesion).

 • Trouble with other nerves controlling the head and face.

 The most common causes of vestibular disease are:

 • Middle ear infection

 • Brain lesion

 • Idiopathic (unknown cause - happens for no reason)
In order to determine prognosis and choosetreatment, one needs to figure out what has happenedto the vestibular system. The first step is to determinewhether the lesion is central (in the brain) orperipheral (in the inner ear).

BRAIN OR CENTRAL LESION
There will be some hints in the clinical presentation that the patient in question has a brain lesion causing the vestibular signs. For example, if other cranial nerves are involved and they are on the side opposite from the head tilt, then the lesion is likely to be in the cerebellum (central). If the nystagmus is vertical (the eyes are moving up and down rather than back and forth)
or only exists when the animal is placed in certain positions, then the lesion is more likely to be central. If the vestibular signs have a central origin, there could be a tumor, vascular accident, infection (especially Rocky Mountain Spotted Fever) or other lesion in the brain. Imaging of the brain will be important in determining the nature of the lesion and what treatment makes the most sense. This means a CT scan or MRI to image the brain and most likely a referral will be needed for this type of procedure. General anesthesia is required for a CT and MRI.

IDIOPATHIC DISEASE
Canine idiopathic vestibular disease (also called “Old dog vestibular disease”) begins acutely and resolves acutely. Usually improvement is evident in 72 hours and the dog is normal in 7-14 days, possibly with an occasional head tilt persisting. When a case of vestibular disease presents, it may be a good idea to wait a few days to see if improvement occurs before doing diagnostics beyond a routine blood/urine database. These two conditions are idiopathic. We do know that they represent problems in the periphery nerves of the middle ear rather than in the actual brain. Treatment of idiopathic vestibular disease generally involves control of nausea (motions sickness) while the condition runs its (relatively short) course.

 IDIOPATHIC VESTIBULAR DISEASE IS THE MOST COMMON FORM OF VESTIBULAR DISEASE IN DOGS

 MIDDLE EAR INFECTION
Middle ear infection is a likely possibility for vestibular disease especially if the patient has a history of ear infections. Concurrent facial nerve paralysis, creating a slackened look to one side of the face, or Horner’s syndrome, where there are some eye changes, often go together with middle ear infection.

 When an otoscope (used to look into the ears) is used to visualize the external ear of an animal with vestibular disease and debris is seen, this would be a good hint that there is infection in the middle ear as well. However, just because debris is not seen in the external ear does not mean that a middle ear infection is unlikely. Special imaging of the middle ear bones may be in order

 The most accessible way to evaluate the middle ear is with a special set of radiographs called a “bulla series” (so named because it focuses on an ear bone called the “tympanic bulla”). If the bulla appears abnormal, the ear may require surgical drainage. The problem is that radiography is often not sensitive enough to pick up damage in the middle ear and a normal set of films does not rule out disease. In these cases, special imaging such as CT Scan or MRI is better (though rather expensive). These imaging techniques, however, allow imaging of the brain tissue itself (which radiology does not) thus allowing brain abnormalities to be evaluated as well.

If a middle ear infection is present but is not known to be present, a routine cleaning of the external ear can lead to a flare up of vestibular symptoms. This is often unavoidable in long standing ear infections.

Treating a known middle ear infection can be difficult. Culture of the middle ear may be necessary and oral antibiotics are needed for 6-8 weeks to clear the infection from the tiny bones of the middle ear. Surgery may be needed to open the tympanic bullae and flush them out.

~Dawn M. Smith

Dog having a CT scan (Photo courtesy of Justin M. Goggin, DVM, Diplomate American College of Vet. Radiology.Vet MRI and RT Center of NJ)