Labrador Retriever Dogs Blog

Ear disease is one of the most common conditions in cats and comes in many shapes and forms – the most serious of which is a regular cause of pet insurance claims.  In this article I look at some of the causes, symptoms and treatments of ear disease, as well as methods of preventing it in the first place.  Although outer ear disease is a relatively minor problem that is easily treated, mid-ear infections can cause permanent damage and inner-ear infections can actually kill a cat.  For this reason, it is important to understand the signs and symptoms of different kinds of ear disease, to ensure that it is treated as quickly as possible.

There are many things that can cause ear problems, including allergies, parasites and microorganisms, as well as hereditary conditions and objects stuck in the ear canal itself.  Ear mites are a common cause of ear disease, especially in kittens, that must be treated with medication and frequent ear cleaning.  Bacterial and yeast infections are another very common cause of ear infections that often come about due to changes within the ear environment – excess moisture, for example.  These infections also require ear cleaning, as well as courses of antibiotics or antifungals, so as to ensure the infection doesn’t spread deeper into the ear.  These changes in the ear environment are commonly caused by allergies, which must also be treated to prevent the problem reoccurring.  To do so, allergy testing is normally conducted and followed up with a supply of antihistamines and fatty acid supplements.  

Common symptoms of ear disease include ear odour, scratching the ears, discharge from the ears and redness of the ear canal.  If the infection moves to the middle of the ear, additional symptoms include shaking or tilting of the head and loss of balance.  Deep ear infections have more obvious symptoms, including vomiting and loss of hearing and coordination.  In these cases surgery is often required, which can be an expensive investment for those without pet insurance.

For all kinds of ear disease, proper care and cleaning for your cat’s ears will go a long way in both preventing and treating the problem.  Cleaning cats’ ears is simple, but the correct procedure cannot realistically be guessed.  The advisable course of action is to lie your cat down and fill its ear canal with ear cleaning fluid, or body-temperature olive oil.  By massaging the base of the ear, you will work the fluid around the ear and release trapped debris.  Finally, use a cotton ball to wipe away the debris and excess fluid before repeating on the other ear.  Although cotton buds can be used to clean the outer ear canal, never attempt to clean deeper into the ear as this is more likely to compact dirt than remove it.

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 Skin and Coat System

The skin and coat system is your pet’s first line of defense to protect against harmful external bacteria and the elements.

Skin:

Smooth, supple skin is essential as a barrier against invaders. Healthy skin can heal more quickly from scratches and cuts. Skin is also the largest organ of the body and will help eliminate toxins when or if the liver becomes overworked and unable to keep up with demand. Healthy skin also holds the coat in better.

Coat:

The coat offers protection from the elements. Since hairs are often shed, there needs to be continuous replacement. The coat may thicken and shed seasonally to help regulate your pet’s body temperature.

Hair Follicles:

Hair follicles, the ‘root’ of the hair, are constantly working. The cells divide every one to three days, with the protein-based cells pushed upward to form the hair itself. With this rapid growth, the hair needs a constant supply of protein to grow.

Omega 6 and Omega 3 fatty acids are among the nutrients that are very important to your pet’s skin and coat. The right amount of high-quality fats and other balanced nutrients help keep skin smooth and supple so it moves with your pet, helps avoid dry skin and promotes a thick, lustrous coat. Protein, amino acids, vitamins and minerals are also key nutrients in promoting healthy skin and coat condition.

The Immune System

The immune system is designed to fight illness, harmful bacteria or other invaders that may attack your pet. It can learn to recognize specific invaders and fight them whenever they are encountered. Natural, raw foods set up and maintain healthy, natural biochemical reactions. These biochemical reactions set up a natural line of defense – a healthy immune system – that fights off bacteria, viruses, and parasites many times a day.

Mucosal:

The lining of the intestine defends against absorbed or ingested invaders. The mucosal lining not only absorbs the nutrients in the food your pet eats, but also filters out harmful bacteria and other invaders, as well as producing antibodies that attack certain disease-causing organisms.

Lymph Nodes:

The lymph nodes filter invading organisms, bacteria and other dangers from the body. They contain lymphocytes, a type of white blood cell that attacks infection, and play a role in developing the antibodies that help give your pet immunity from certain illnesses. There are lymph nodes clustered throughout your pet’s body.

Bone Marrow:

The bone marrow, contained in the center of bones, produces white blood cells, one of the body’s primary defenses against infection. These cells travel in the bloodstream and attack and destroy invaders. When there is an infection underway, more white blood cells are produced. Antibodies are made of protein, and the amino acids in protein are the raw material used to build white blood cells and components of the immune system. One of the keys to supporting a healthy immune system is an adequate supply of good quality animal protein.

The Digestive System

In addition to delivering nutrients from food to your pet, the digestive system serves as a barrier to internal invaders, like skin does for external invaders. It also produces antibodies and is home to helpful bacteria that perform a variety of crucial roles.

Stomach:

This is the first stop for food and ingested material. The stomach is where food begins to be broken down in preparation for absorption. It is a mixing place for various enzymes and digestive juices.

Intestines:

The intestines are where nutrients, minerals and water are absorbed for use by the body. An effective digestive system also will destroy invading organisms and other undesirable substances.

Liver:

The main function of the liver is to aid in the metabolism of food and to produce important chemicals, such as bile acids that help digest fats. In this way, it helps turn food into usable building blocks and energy for your pet. It also protects the body by acting as a filter of absorbed or ingested toxins, and produces substances that help blood clot.

By restoring your pet to his natural, health-giving diet, you can restore the myriad natural biochemical reactions that give strength to his immune system. This is the “magic” that keeps pets who are fed natural diets free of disease.