Introduction to Otitis Media and vestibular system in pets

The vestibular system is the part of your body that controls balance. When you are having a problem in your vestibular system you become dizzy. This dizziness can lead to a head tilt, rapid eye movements, problems standing up and nausea.

The vestibular system is located in two places in your pet’s body: the inner ear and brain. A deep ear infection can affect the inner ear. This is a deep ear problem, behind the eardrum and near your pet’s skull.

Symptoms of otitis Media/Interna

Head tilt
Circling
Leaning, falling or rolling
Abnormal eye position (Strabismus)
Ticking movements of the eyes (Nystagmus)
Small pupil, with a slightly closed eye (Horner’s Syndrome)
Drooping lip or ear, or inability to blink (Facial Paralysis)
Ear pain or itching
Discharge from the ear
Hearing loss

In this diagram we see all the parts of a dogs ear. The part of the ear we can see is called the pinnae. The vertical and horizontal canal make up the ear canal. The sharp turn can make it difficult to see the ear drum, aka the tympanic membrane. The middle ear is a large bony chamber that is normally filled with air. In an infection, it fills with pus. Finally in the inner ear we have the structures that control balance as well as our ability to hear.

Underlying causes of Otitis Media/Interna

Very commonly, dogs and cats develop otitis media/interna secondary to another problem. For instance, 39% of dogs with otitis media/interna have underlying food allergies that result in skin disease. This condition is known as atopy, and it's quite common.

Treating this underlying condition is crucial for long-term success. If we don't address the underlying cause, the problem is very likely to recur.

Underlying causes in dogs

Atopy
Short faced breeds (Pugs, Bulldogs, Shiatzus)
Fox tail or other plant matter in ear
Narrow ear canals or presence of hair
Ear mites

Underlying causes in Cats

Upper respiratory infections
Short faced breeds (i.e. Persians)
Polyps: these growths form secondary to inflammation.
Facial abscesses
Ear mites

Diagnosis of Otitis media/interna

Otitis media/interna can occasionally be diagnosed solely through an ear exam. If your pet has a ruptured eardrum, or if we can see material behind the eardrum, that’s usually indicative of otitis media/interna. However, this condition can only be diagnosed through an exam about half the time because the eardrum is not always visible. Even if it is visible, it doesn’t always provide conclusive evidence.

The condition is best diagnosed with advanced imaging, such as a CT scan or MRI. Often, an MRI is preferred because it allows us to simultaneously assess the health of the brain. While some pets may be diagnosed with just an ear exam, many ear structures are not visible during this exam, so it's important to realize that some conditions might be missed with only a visual exam.

In more complex cases, or when another disease may be masquerading as an ear infection, advanced imaging becomes even more crucial. For example, some ear tumors can become infected and initially appear as ear infections. In cats, polyps that grow secondary to infections may need to be removed. Advanced imaging can help distinguish these various conditions.

An MRI showing otitis media/interna in a dog

This is an MRI showing fluid in the middle ear of a dog (arrow). A culture would be needed to know for sure if this is an infection.

An MRI showing otitis media/interna in a cat

This is an MRI showing fluid in the middle ear of a cat (arrow). A culture and a PCR test for common cat viral infections helps us determine how to best treat this.

Treatment

We often recommend a myringotomy for pets with this condition. In this procedure, we make a small hole in the eardrum and flush out the pus trapped behind it. This step also allows us to culture the area and select the most effective antibiotic. Post-procedure, your pet’s symptoms may temporarily worsen due to irritation; however, this is usually short-lived and improves within a few days. While rare, there is a risk of permanent damage from the procedure. The primary benefit of a myringotomy is that it enables us to remove a significant amount of infected material, potentially speeding up your pet's recovery, and allows for accurate culture testing.

Your pet will be prescribed both topical and oral medications. These infections can be stubborn, requiring treatment for at least six weeks, sometimes longer. It’s crucial to refill your medications on time to avoid running out. Unfortunately, some patients may not respond to medical therapy despite our best efforts. If this is the case with your pet, we will refer you to a surgeon to discuss the possibility of ear surgery.

Prognosis

Studies have shown that 82% of dogs with otitis media/interna can be successfully managed with medications and ear flushing, and similar success rates have been observed in cats. It's very important to address any underlying causes, such as food allergies in dogs or upper respiratory infections in cats, as failure to do so may lead to recurrence of the infection.

In animals that do not respond to medical management, surgery is sometimes recommended, which often resolves the problem.

Unfortunately, sometimes the damage caused to the nerves by this infection is permanent. As a result, some symptoms, like a head tilt or facial paralysis, may persist despite successful treatment.