Ear Cysts (Cholesteatoma) in Dogs

Ear infections or otitis can affect any part of the ear. Most infections are of the outer ear (otitis extera), but sometimes bacteria can spread to the middle part of the ear (otitis media), especially if the ear drum is damaged or ruptured. Cholesteatoma is a rare condition that can with occur otitis media. It is a cyst or growth that forms around the eardrum (tympanic membrane) and extends into the bony cavity of the middle ear (the tympanic bulla). It usually occurs in dogs with chronic or recurring ear infections. Cholesteatoma is made up of epithelium cells, the cells that normally line the ear canal.  In this case, the cells have become infected, causing them to build up in several layers and secrete the protein keratin.  This is not considered a cancerous growth, but cholesteatoma do expand over time. They can put pressure on the surrounding bones and tissues and sometimes may even spread to the inner ear or the lining of the brain. Dogs with severe cases have neural ticks in the face and eyes, as well as difficulty opening their mouths or swallowing. Surgery is the best option, but in about 50% of cases the cholesteatoma returns because all of the infected material was not removed. Imaging techniques like CT scans and MRI have made cholesteatoma more detectable in the early stages when it is easier to remove effectively.

Chronic ear infection in dogs can lead to the development of an abnormal growth or cyst in the middle part of the ear. Veterinarians called this condition cholesteatoma. This is a rare condition in dogs. It is not cancerous, but the infected material will spread and can cause problems if it is not removed with surgery.

Early symptoms look like a typical ear infection with pain and irritation of the ear. Neural symptoms develop later. Take your dog to the veterinarian if you notice any of the following signs:

• Head shaking
• Pawing at ear
• Rubbing ear on the ground
• Tilting or rotating head towards the affected side
• Facial paralysis
• Drooping eyelid or constricted pupil on the affected side
• Nystagmus (involuntary eye movements)
• Circling
• Lack of coordination
• Loss of balance
• Inability to open mouth
• Reluctance to eat
• Dysphagia (inability to swallow)

Types

This is a rare condition in dogs which is only beginning to be routinely diagnosed. Some cholesteatoma have formed into hard lesions, while others are a spongy keratinous fluid filling the tympanic bulla. Various types of bacteria are present, many of which have become resistant to antibiotics.

Cholesteatoma is generally associated with ear infections, but it may also occur after recent surgery. These are some of the causes that have been noted.

• Chronic or recurrent ear infections (otitis)
• Rupture of the eardrum
• Eardrum bulging into the inner ear
• Prior surgery
• Congenital abnormality
• More common in males
• More likelihood of recurrence in brachycephalic breeds (breeds with very short noses such as pugs and bulldogs) due to the increased difficulty with cleaning out the ear canal.

The veterinarian will be able to see that your dog has an ear infection on a physical examination. Sometimes anesthesia or sedation can be necessary to make a complete examination, especially if the ear is painful. If your dog has a history of chronic or recurrent ear infections that do not respond well to antibiotics, a CT scan or an MRI will likely be taken of your dog’s ear. This would also require sedation or anesthesia. Contrast dyes can sometimes be used to make the abnormal growth more visible. Nasopharyngeal endoscopy may be necessary to obtain biopsies of the tissue inside the middle ear. The cells will be analyzed at a microscopic level and tested for bacteria.

The veterinarian will want to know your dog’s medical history, especially any prior ear infections. A detailed description of the symptoms will help to determine the severity of the problem.

Surgery is the recommended treatment for cholesteatoma. The surgery is usually a total ear canal ablation (TECLA) and/or lateral bulla osteotomy (LBO.) The veterinarian will attempt to clear all the infected material out of the ear canal and the tympanic bulla. This is minor surgery, although it can be tricky due to the shape of the ear. In some cases, several surgeries may be necessary as well as continued treatment with antibiotics. Dogs with difficulty opening their mouth or swallowing generally have more severe cases which are likely to recur.

In some cases surgery is not an option, either because the condition has already progressed too far or the dog is not healthy enough for surgery. In this case, the symptoms will usually get progressively worse and the dog will eventually have to be euthanized.

Dogs who are treated early for mild cholesteatoma are much more likely to make a full recovery. Dogs with very severe symptoms may respond initially to surgery, but the condition will often return within 6-12 months. In this case, it could be difficult to fully eliminate the problem and a long term treatment plan would need to be discussed with the veterinarian. Regular check-ups and prompt treatment for any signs of ear infection are recommended in order to prevent the development of cholesteatoma.