The vestibular system

The vestibular system is the body’s ‘balance messenger’ – giving mammals (including humans and pets) key sensory information that allows us to stay upright and properly orientated in the world. The vestibular system is made up of two main components: the inner ear and the brain.

In the inner ear, the vestibular system is made up of tiny sensitive bones, membranes and tiny hairs, all strategically positioned to send signals about balance and where your limbs are and how your body is moving also called your spatial orientation. An example of this will, for instance, be your brain sending and receiving messages about which way your head is moving. The different parts of the brain involved in the vestibular system receive the sensory information from the ear and other body structures and help them to all function together to give you a perception of balance. The eyes, the head, the body and the legs are all included, allowing for smooth, balanced and harmonised movement. The proper functioning of the vestibular system allows you to stand on one leg and touch your finger to your nose without falling over.

What is vestibular disease?

Vestibular disease shows up as the sudden onset of balance problems in your pet. The causes of vestibular disease can originate either from the inner ear (peripheral (outside)) or from the brain (central (inside)). How it is diagnosed and treated will depend on the cause (infection, trauma, structural changes or hormonal influence) and the location (inner ear or brain).

How does vestibular disease occur?

Most cases of vestibular disease occur as a result of infection and inflammation of the inner ear (peripheral vestibular disease). Long-standing outer ear infections can progress to middle and inner ear infection leading to vestibular disease in pets. Ear infections at the best of times are difficult to treat because it in itself have many different causes. The ear canal in dogs and cats is much longer than the human ear canal and consist of two parts, the vertical ear canal and the horizontal ear canal. The long ear canal can in many cases contribute to ear infections, but sometimes ear infections are not primarily related to the ears but can be as a result of general skin allergies which then causes ear infections as a secondary problem. Because severe ear infections can lead to vestibular disease, which is a really serious condition, it is important to treat ear infections as early as possible. Other causes of peripheral vestibular disease can be due to damage to the bones protecting the inner ear as caused by head trauma, abnormal growths in this area, certain medications and even hormonal abnormalities such as low thyroid levels.

Central vestibular disease, which affects the brain, is more serious and can be caused by abnormalities in the brain or the membranes protecting it. This can result from bacterial or viral infections such as meningitis, abnormal growths, toxins or even a stroke.

What symptoms will I see in vestibular disease?

The cause of the disease will determine the signs you will see. The most common sign of both peripheral and central vestibular disease is a head tilt to one side. The head tilt almost always affects only one side; with one ear up in the air and the other pointing down. The downward ear is usually the culprit for the discomfort.

The head tilt can vary in severity – from a barely noticeable tilt to tilting all the way to the side, where your pet looks like they’ll fall over. Some pets develop instability where they tend to lean to one side or even fall and roll to the same side as the head tilt. Sometimes pets will walk in tight circles, always in the same direction toward the problematic ear. In some cases, the vertigo and dizziness can cause nausea where pets drool, lick their lips or even upend their dinner. Pets with outer ear infections often scratch their ears and shake their heads with irritation. Some pets with inner ear infections can develop signs of Horner’s Syndrome, where one side of the face may droop, one eyelid hangs, the third eyelid partially covers the eye and there is a change in the size of the pupil. Sometimes one eye appears squint and looks in a different direction to the other, especially when the pet’s head is lifted up.  

If the cause is located in the brain there will be subtle signs such as poor appetite and sleeping more than usual; as well as more frightening signs such as weakness of the legs to paralysis and seizures.

Is vestibular disease treatable?

Treating vestibular disease depends on the cause of the problem. If the problem originates with an inner ear infection, the vet can usually treat it with anti-inflammatories and antibiotics. However, if the problem is more complex and affects the brain or is caused by abnormal growths, the treatment decision would depend on what is found. If your pet is nauseated or vomiting, your vet can assist with anti-nausea medication.

What do I do if I suspect my pet might be affected?

The best option would be to bring your pet to the vet for a full checkup. The vet could first determine if vestibular disease is a problem in your pet and pinpoint the source of the problem, whether it be peripheral or central. It is important to mention to the vet when you first noticed any signs and how it has progressed over time, as well as if your pet is on any medication.

The vet will do a full check on your pet. This may include examining your pet’s ears with an otoscope, test nerve and brain responses, and the vet may even recommend x-rays to have a better idea of what is going on in the inner ear. If a brain-based problem is suspected, a Computed Tomography scan (CT or CAT scan) or Magnetic Resonance Imaging scan (MRI scan) might be recommended. These procedures are highly specialised and most veterinary practices do not have the equipment to do these scans in house and you may need to be referred to a veterinary specialist.

When is vestibular disease a problem?

On the basic level, vestibular disease can be a problem if your pet is falling over and hurting themselves, or even falling into the pool and unable to get out. Ear infections are uncomfortable and often painful and will not come right by itself.

On a more serious level, a head tilt can be the tip of the iceberg and may be the first sign of a very serious problem. If your pet has vestibular disease, it is something that does require further investigation and treatment – it will not simply come right on its own.

Either way, if you see your pet persistently tilting their head to the side,  please make an appointment with the veterinary practice.

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