Labrador Retriever Dogs Blog

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 or 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 or 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.

The inside lining of the ear is normally smooth with a small amount of wax buildup. Many problems can cause the ears to be irritated, inflamed and/or infected. Any of these causes left untreated can lead to more complicated problems, including middle and inner ear damage and hearing loss. Most cats let you know that their ears are uncomfortable by scratching, shaking and/or tilting their heads.

CAUSES

Ear mites are most common in ear problems adult cats and puppies. These microscopic mites have hairs on their body that irritate the ears. They are also responsible for the itching and the dark brown, coffee-like residue. Mites live primarily within the ear canal. They can also live outside of the ear and on other parts of the cats body, they do not infest your home.

* Trauma to the ear from foreign materials like plant seeds or over-aggressive cleaning can also cause pain and inflammation of the ears.

* Flea allergies can occasionally involve the ears.

* Allergic reactions to pollen, mold, and dust are not common in ears. Ear infections associated with allergies often recur until the underlying cause of the allergy is determined and treated.

SYMPTOMS

* Scratch ears often.

* Shake or tilt head.

* Odor and/or discharge from ears.

WHAT YOUR VET CAN DO

* Diagnosis involves examining a sample of the ear discharge under the microscope. This is called a Cytology and will identify the problem. The most effective treatment will be determined according to whether mites, yeast or bacteria are present.

* Ear mites can also live outside of the ear, on other parts of your cat’s body. Flea control products can help to manage this problem.

* Instead of using eardrops to treat mite infections, you can now purchase a new topical treatment called Revolution (selamectin), applied onto the skin at 30 day intervals, which controls fleas, ticks, heartworms, intestinal worms and ear mites for cats and dogs.

* To prevent ear problems, check your cat’s ears regularly. Only use products recommended by your vet to clean your cat’s ears, and never clean any deeper than you can see.

* Long-term and/or recurrent ear infections may require a culture to pinpoint the exact agent responsible and the medication best suited to eliminate the infection.

NOTE: An otoscope is designed and illuminated to allow complete visualization of the ear canal

HEMATOMA (BLOODCLOT) OF THE EAR

* Hematomas usually occur as a result of self-inflicted trauma to the ear. Many cats vigorously Itch their ears because of a persistent underlying ear mite problem. A blood vessel in the earflap ruptures which causes bleeding into the earflap tissue. Treatment usually requires surgical

removal of blood clots and drainage of blood under anesthesia. Hematomas tend to recur until the underlying problem is eliminated because the cats continue to traumatize their ears by itching. Many ears scar down into an abnormal appearance.

TREATMENT

Milbemycin, is the active ingredient in Sentinel, a tablet given monthly to prevent heartworms, fleas, intestinal worms, and ear mites in cats. Selamectin is the active ingredient in Revolution, approved in cats, a monthly product that kills ear mites and walking dandruff mites, and prevents heartworms and fleas. New monthly flea preventative products have replaced ear drops to treat ear mites.

COMPLEMENTARY EAR TREATMENTS

Yeast Infections: Mixing equal parts of white vinegar and water (50:50) makes a good ear cleaning solution for yeast.

Bacterial Ear Infections: Garlic can be added to the diet only occasionally, continual high doses can cause anemia:

* Garlic has antibacterial and antifungal effects.

HERBALEAR REMEDIES

* Mullein (Verbascom thapsus)

* Mucilage or Sapenins have a demilucent effect.

* Use topically for bacterial ear infections.

* Calendula makes an effective ear cleaning solution: Mix one teaspoon of Calendula with a teaspoon sea salt and one cup of water.

* Calendula Oil is soothing to red inflamed ears. Apply two drops into ears once daily.

* To eliminate ear mites, Yellow Duck (Rumex crispus) two drops every 3rd day for three to six weeks.

HOMEOPATHIC EAR REMEDIES

For red, irritated ears try Pulsatilla (6c Windflower) one pellet every third day for two weeks. Withhold food ten minutes before and after treatment. Sepia officinalis (30C) two whole or three crushed pellets by mouth twice a day for three days then once a week, until the ears are healed. Helpful with itching and head shaking.

VESTIBULAR (MIDDLE EAR) DISEASE

Long-term and/or recurrent ear infections can spread to involve the middle ear. The middle ear houses nerves, called Vestibular nerves, which are responsible for balance and equilibrium. If these nerves are irritated, cats can lose their balance, tilt their heads, stagger and often fall over. This is called Vestibular Disease. Some cases are associated with ear infections and rarely brain tumors are responsible but the cause in most cases is unknown or idiopathic. The term Idiopathic Vestibular Disease is used in these cases.

DIAGNOSIS

X-rays are initially used to evaluate the middle ear. The bone housing the middle ear is called the Tympanic bulla and is located within the brain. The series of x-rays taken in this case, is respectively called a “Bulla Series”. A CAT scan or MRI are more sensitive imaging techniques that may be necessary to allow visualization of this area of the brain if the x-rays are inconclusive.

Typically, most cases of Idiopathic Vestibular Syndrome occur for some as of yet unknown reason in the spring and fall. Cats suddenly tilt their heads and begin staggering, for no apparent reason. Cats generally improve within 72 hours and symptoms usually resolve in a couple weeks. Occasionally the head tilt persists.

If you notice your dog or cat is scratching at its ears, shaking its head and its ears don’t smell too great, chances are your pet has ear mites. You can get rid of ear mites through some natural home remedies, or with medicine from the vet.

Ear mites are parasites which live off the bodily fluids of your pet. As the name implies, ear mites prefer residing in the ears. Ear mites resemble the look of coffee grounds or red, brown and black dirt. The inside of the ear will also look red and a little inflamed. You cannot see the ear mite with the naked eye.

Pets get ear mites due to poor hygiene and dirty surroundings. They are contagious with respect to other animals. If you insist that your pet is kept very clean and lives in pristine conditions, it is possible that the ear mites were caused by being around another animal who has ear mites, or your pet has exceptionally long, floppy ears which are especially susceptible to ear mite infestation.

It certainly is important to keep your and your pet’s surroundings as clean as possible and regular bathe your pet. Keep all other pets in your home away from the infected one and wash those additional pets regularly as well. It is imperative that you take action to rid your pet of ear mites because allowing the ear mites to remain in your pet’s ears will lead to deafness.

If you have an infected cat, you can use mineral oil to get rid of the ear mites. Simply place drops in the infected ear or ears, which will loosen up crusty build up. You can then take a small cotton ball to wipe out the build up. However, if your cat’s ears are raw and inflamed, the best thing to do is take it to the vet to make sure there is not some other problem with your cat’s ears.

If your dog is infected with ear mites, make sure to wipe its ears on a daily basis. You can make a mixture of garlic and olive oil and then put some drops in each infected ear. If you do not notice any change after a few days and your dog’s ears are raw and inflamed, take the dog to the vet to see if your dog has some other ailment.