vestibular

Vestibular Syndrome is dizziness caused by a failure of the vestibular system – the organs involved with the sense of balance. The vestibular system consists of part of the inner ear called the semi-circular canals and regions of the brain that process the sense of balance. Usually only one side stops working, so the dog loses its sense of which way up it should be.

The dog appears dizzy or drunk and if it can stand it will tend to walk in circles and fall over to one side. Many dogs are unable to stand and will lie on one side only. The eyes tend to flick from side to side, moving slowly in one direction and flicking quickly back. They will often pant and may vomit. If able to stand, the head will often be tilted to one side.

Vestibular syndrome can be caused by an infection in the middle ear that spreads to affect the inner ear. In these cases, there is often pain in one of the ears and head shaking may have been present for some time previously.

The cause is unknown In most cases of vestibular syndrome. This is known as Idiopathic Vestibular Syndrome. This occurs in older dogs and is often referred to as a “stroke” to help people understand what has happened to their dog, although the cause is not the same as a stroke in humans – there is no blood clot or bleed to cause it. Factors that seem to be related to incidence of this problem include general anaesthetics, heart disease, poor circulation and very hot weather. These are all factors that can affect the blood flow in the brain and all indications are that the cause is a disruption of the blood flow to part of the brain. There are similarities with Meniere’s Disease in humans. It is possible for a blow to the head to cause vestibular syndrome, but this is rare.

Provided that only the vestibular system is affected, the prognosis is usually very good for a full recovery. However, in some cases, other parts of the brain can be affected at the same time. Generally, if the dog is able to recognise its owner and is at least partly aware of what is going on, it will recover eventually.

If an underlying cause is suspected, then treatment must be given for that. A middle ear infection will require antibiotics and anti-inflammatory drugs. No drugs have definitely been proven to help dogs recover from Idiopathic Vestibular Syndrome. An injection of steroid soon after it occurs has been proven to help many brain injuries, so it is possible this will speed recovery. Otherwise drugs that help to improve the blood flow to the brain are often given, such as Vivitonin or Fitergol, particularly if the dog has other evidence of poor circulation.

Treatment is aimed at making the dog more comfortable. Drugs may be given to prevent vomiting and if the dog is unable to settle, tranquillisers will help. In the early stages it is best for the dog to rest quietly lying down. They may require help taking food and drink until they regain some stability. Once they start to feel better in themselves, particularly after the eyes have stopped flickering, it is useful for them to try and get around. When they first start moving around again, they will be unstable and fall often. To help them through this phase it is best to protect them from falling on hard floors/objects and to loop a towel under the body when they walk to help them. They should not have access to stairs without help. Lifting them off the floor at this stage is often distressing – they learn to use the floor as a reference for their balance. Walking around at this stage will speed their recovery – it is largely a learning process, so practice helps.

Most dogs will make a reasonable recovery within 2 weeks of the problem starting. In many cases, it seems that the damage does not repair, but rather the brain learns to cope with the change in the sense of balance. The dog is often left with a head tilt, usually worse than when the problem first started, but will be able to get around normally. Many people contemplate euthanasia when a vestibular attack occurs. However, if the dog is otherwise in good health and aware of the people around them, the prognosis is good, although it takes a little time. If, however, the dog is already suffering with poor health or seems to have suffered damage to other parts of the brain also, euthansia may be the kindest option.

Canine Vestibular Disease

The Peoria Humane Society
http://www.peoriahs.org

One day our 15 year old dog became disoriented, unbalanced and appeared to be confused. He was leaning toward one side, shaking his head, going around in circles, etc. We thought he may have had a stroke and took him to the emergency animal clinic. Instead of stroke it turned out he was suffering from Canine Vestibular Disease—also known as “old dog vestibular syndrome.”

Vestibular means a problem with the connections between inner/middle ear and brain causing ataxia. Dogs with ataxia stand with their limbs braced, they walk with difficulty and have a “drunk” type of motion because they have lost their sense of balance. When the vestibular nerve, which travels from the inner ear to the brain, malfunctions. It disrupts the animal’s sense of balance and orientation.

It is important to find out where the vestibular abnormality is located. The disturbance can be peripheral, meaning it is located outside the brain, or central, located inside the brain. The distinction between the two is subtle and is best diagnosed by a veterinary neurologist. The peripheral disturbance is the most common and least serious.

It has been suggested that there is a correlation between old dog vestibular syndrome and hypothyroidism so blood work should be done to rule out this problem.

The ears should be thoroughly examined because the same symptoms can result from a severe ear mite infection. Also certain types of antibiotics such as streptomycin and gentomicin can cause vestibular syndrome.

This syndrome is not a life threatening condition, nor should it even be called old dog vestibular syndrome because young dogs have also contracted it. However, in most cases old dogs are seen by veterinarians with this condition more often.

Time is a major factor in old dog vestibular syndrome. Recovery time depends on the afflicted dog. Eventually the animal teaches itself to compensate and overcome old dog vestibular. Rest and quiet are required during this recovery time, and it’s important to keep the dog in a well lighted room. If possible, avoid carrying the dog, or, if this is unavoidable, lift the dog slowly and smoothly and hold the pads of it’s feet while airborne. Lifting and moving it through the air disrupts the dog’s sense of orientation. Keeping the dog’s feet firmly on the ground with it’s eyes on the horizon helps regain it’s balance. This condition is sometimes misdiagnosed and dogs who could have recovered have been euthanized because the condition appears so severe. It is important to note that there are no warning signs, which may lead to the conclusion that it is a stroke. Fortunately most dogs will be spared this affliction. However, if your dog does contract this disease, it is comforting to know that it is not fatal and recovery is merely a matter of patience and tender loving care. Please note that a serious inner/middle ear infection—which can occur without the customary smelly ear—has the same severe and frightening symptoms. An infection can usually be cured with antibiotics and the dogs have a complete recovery. Drugs that might be used to treat old dog vestibular syndrome include Cholodin Tabs and Winstrol V. As always, check with your vet.

reprinted with kind permission from Patti Schaffner Peoria Humane Society phscrc@yahoo.com

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Vestibular Disease in Dogs and Cats

Dr Matthew Homfray
www.whydoesmypet.com

The vestibular system controls balance and prevents an animal from falling over. It does this by holding and constantly adjusting the position of the eyes, head and body in relation to gravity. When there is disease affecting this system, though it is seldom life threatening, the symptoms caused can be particularly distressing for a pet owner. Animals may tilt their head to one side, circle either clockwise or anticlockwise, fall over repeatedly, roll to one side, be generally wobbly and display abnormal pupil movement in their eyes. Here we look at the physiology of the vestibular system in dogs and cats, what can go wrong and how a good veterinarian will diagnose and treat it.

What exactly is the vestibular system?
The vestibular system is a sensory system consisting of a receptor organ within the inner ear, the vestibular nerve itself, and a balance control centre at the back of the brain. The receptor organ in the inner ear detects the position and movement of the head in space, both when the animal is resting or moving. Information on the position of the head is converted into electrical signals, which are transmitted via the vestibular nerve to the brain. The balance control centre in the brain then processed this information, and sends motor signals to the muscles controlling the positions of the eyes and limbs according to the movement of the head.

What is vestibular syndrome?
Vestibular syndrome is a general term describing disease of the vestibular system. The term alone does not provide any information on which part of the vestibular system is affected, and what the cause is.

What are the signs to look out for?
Animals with vestibular disease may display any or all of the following signs:

1. Head tilt
This is rotation of the head so that one ear is lower than the other. It occurs due to loss of antigravity muscle tone on one side of the neck.

2. Circling
Circling often occurs with vestibular disease, but can also occur with forebrain tumors. Generally, tight circles mean vestibular disease while wide circles mean a brain tumor.

3. Nystagmus (wandering pupils)
This means involuntary rhythmic movement of the eyeballs. The pupils tend to drift to one side (the slow phase) and then jerk back to the middle (the fast phase). Usually the slow phase is toward the diseased side.

4. Strabismus (squint)
This means abnormal position of the eyeballs, rather like the condition commonly known as a squint.

5. Ataxia (wobbliness)
This means walking in an uncoordinated fashion, and is seen with a wide range of diseases other than vestibular disease, such as those affecting the brain, spinal cord or peripheral nerves. Animals can adopt a broad based stance, exhibit swaying of the head, and leaning, falling and rolling to one side.

Peripheral vs Central Vestibular Disease
Vestibular disease is categorized as either peripheral or central, according to where in the system the disease originates from. Peripheral vestibular disease is where the disease is located in either the receptor organs in the inner ear or the vestibular nerve. Central vestibular disease is where the disease is located in the balance control centre in the brain (to be precise, either in the brainstem vestibular nuclei or in the cerebellum).

The first task for the veterinarian is to identify whether he/she is dealing with peripheral or central vestibular disease. This is done by looking carefully for all of the symptoms described above, and further characterizing them by direction and nature. It is beyond the remit of this article to go into the exact way of differentiating them clinically, and though it can usually be achieved by a competent vet by examination alone, sometimes further tests are necessary to do so.

Causes of peripheral vestibular syndrome

1. Middle or inner ear disease (infection or tumor)
2. Nasopharyngeal polyps
3. Head trauma
4. Drug toxicity (e.g. gentamycin)
5. Underactive thyroid gland
6. Congenital (present at birth)
7. Idiopathic (cause unidentifiable)

Causes of central vestibular syndrome

1. Brain hemorrhage or infarct
2. Infectious encephalitis (bacterial, viral or fungal)
3. Meningoencephalitis
4. Head trauma
5. Drug toxicity (e.g. metronidazole)
6. Brain cyst
7. Brain tumor (primary or metastatic)
8. Thiamine deficiency
9. Neurodegenerative disease

Making a diagnosis
First, the veterinarian must distinguish between peripheral and central disease based on clinical signs. If there is doubt, diagnostics for both should be done. If the veterinarian suspects central disease, he/she may choose to rule out peripheral disease with various tests first because the tests for central disease are expensive (e.g. MRI or CT scan).

The following procedure is what is most commonly done when looking for causes of peripheral vestibular disease. If drug toxicity has been ruled out (no metronidazole, aminoglycoside antibiotics or topical chlorhexidine recently) then the external ears are examined using an otoscope (illuminated and magnified inspection device with a rigid conical end which is inserted into the ear canal). Ear infections, tumors and polyps may be detected this way. Middle ear disease is suspected if the ear drum appears to be ruptured, bulging, cloudy or red in color. Thyroid levels are usually measured by a blood test at this stage to rule out hypothyroidism.

The next step of the investigation is taking xrays of the skull. Several views are required but the most important one is that which shows the tympanic bullae in the middle ears most clearly. This requires general anesthesia to allow correct positioning.

If the tests at this stage have all come back normal, many cases will be given a presumptive diagnosis of idiopathic vestibular syndrome. This is usually because a) it is by far the most likely diagnosis, and b) further specialized tests are costly. If however further tests are to be carried out, MRI or CT scanning, electromyography and nerve conduction studies are a possibility in some referral centers.

Author: Dr Matthew Homfray
Website: http://www.whydoesmypet.com
Description: A new pet Q&A service connecting pet owners worldwide directly with veterinarians, vet techs, vet nurses, behaviorists, trainers, breeders, groomers, homeopaths and general enthusiasts. Visit us today, you will be impressed by the quality of our experts and the speed with which they respond to your question!
reprinted with kind permission from David Brooks

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Vestibular Disease in Animals

The above information is simply informational. It's intent is not to replace the advice of a veterinarian nor to assist you in making a diagnosis of your pet. Please consult with your own veterinarian for confirmation of any diagnosis. Your pets life may depend on it.

CANINE VESTIBULAR DISEASE

Canine Vestibular Disease

Vestibular Disease in Dogs and Cats