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Cholesteatoma in Dogs

Dogs have an "L" shaped ear canal. At the bottom end of the "L" is the eardrum (tympanic membrane), and behind the eardrum is the middle ear. When the ear becomes infected, only the outer, "L" shaped portion of the ear is usually affected, a condition referred to as otitis externa. Sometimes, the middle ear will become infected as well, in a condition referred to as otitis media. Infections of the middle ear can occur if the eardrum is ruptured or if an infection of the outer ear goes on for a long time. When middle ear infections go on for a long time, one of the complications that may follow is the formation of a cyst (fluid filled sac) near the eardrum. This cyst is called a cholesteatoma.

Symptoms and Types

• Infection in one or both ears, present for a long time (chronic)
• Shaking the head a lot
• Pawing or scratching at the ears
• Pain when eating
• Pain when yawning
• Pain when the jaws are handled
• Rarely, head tilted to one side or difficulty walking
• Rarely, deafness or decrease in hearing

Causes

Ear infections that are present for a long time, sometimes more than a year, are the most common cause of cholesteatomas in dogs. All breeds and ages of dogs have been reported to get cholesteatomas, though some breeds may have certain physical characteristics that predispose them to ear problems.

• Ear Infection
• Ear mites
• Foreign bodies (e.g., grass awns)
• Excessive use of cleaning agents or swabs in the ear canals
• Predisposing factors
• Breeds with narrow ear canals and/or excessively folded ears
• Excessive hair in the ear canal

Diagnosis

You will need to give a thorough history of your dog’s health, onset of symptoms, and possible incidents that might have led to this condition. Your veterinarian will use a diagnostic tool called an otoscope, an instrument with a light and a cone on one end that is designed for examining the ear. This will help your veterinarian to identify any kind of material or presence of discharge in your dog’s ear canal, as well as to determine how swollen the ear canal is. Your veterinarian will also be looking for any damage to the eardrum. Often, in the case of a long-term ear infection, your veterinarian will not be able to see the eardrum because of swelling and discharge in the ear canal. A sample of the material in your dog’s ears will be taken for culture to determine what bacteria may be causing your dog’s ear infection. Your veterinarian will also order x-ray imaging of your dog’s head. These x-rays will allow your veterinarian to look at the middle part of the ear (behind the ear drum) that cannot be seen with an otoscope. X-rays will also help to identify how much of the ear is involved and whether or not the jaw is also involved. Your veterinarian may also order a computed tomography (CT) scan if the x-rays do not provide enough information to confirm a diagnosis. A CT scan will give very detailed information about how much of your dog’s ear is involved in the infection. This will assist your veterinarian in deciding what the best therapy will be for your dog.