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Ear's to you!

1/15/2004

Head shaking, ear rubbing, pain, and an unpleasant odor— your dog has all the symptoms of otitis externa — an inflammation of the outer ear canal. Otitis externa can have a variety of causes; the most important part of resolving the symptoms is to control the underlying factors that make ears prone to inflammation.

Primary factors are those that directly cause inflammation and infection. Common primary causes include parasites (mites, chiggers, ticks), foreign bodies (sticks, grass awns), seborrhea, immune mediated diseases, hormonal problems (thyroid hormone deficiency or adrenal hormone excess), tumors or polyps, and allergies.

Predisposing factors increase the likelihood of developing inflammation, although they do not cause infection by themselves. Predisposing causes may include abnormalities in conformation (narrow ear canals or a floppy ear flap) or an increase in the number of glands within the ear. Environmental conditions such as high humidity, prolonged moisture ("swimmer's ear"), or trauma (i.e. from cotton swabs) can also predispose animals to inflammation.

Inflammation of the ear canals is perpetuated by the presence of microorganisms — bacteria or yeast, and by middle ear infections, inappropriate treatment, and thickening and proliferation of the ear canal ("cauliflower ears"). Ear inflammation may temporarily improve with treatments that focus on clearing up the bacteria and yeast, but the otitis will be back if the primary and predisposing causes are not identified.

After performing a general physical examination, your veterinarian will want to examine your dog's ear canals with an otoscope. This may require a sedative or even anesthesia if your dog's ear canals are very painful. Occasionally the source of the inflammation, such as a tick or grass awn, can be found and removed with small forceps.

During the examination a swab of each ear canal will be taken so that the ear canal contents can be examined under a microscope. Presence of bacteria, yeast, and mites can be detected with these samples.

If your veterinarian sees any abnormal growths with the otoscope, she may also be able to take some tissue biopsies. A pathologist can evaluate the samples to determine whether polyps or tumors are present. Depending on physical examination findings, other tests such as x-rays or blood work may also be recommended.

Ear cleaning is a critical part of treating otitis, and the type of ear cleanser should be tailored to your dog's needs. Cleaning agents can help break up wax, flush out debris, change the pH, or even dry out the ear canal, and are usually used 1-2 times a week until the ears improve.

Never use cotton swabs to clean out your dog's ears — this can actually make them worse!

Several types of ear medications are available for reducing inflammation or killing yeast, bacteria, or mites. Remember to follow all directions and to complete the treatment, since under- or over-treating can perpetuate inflammation and infection.

If swelling is moderate to severe, systemic steroids (prednisone or prednisolone pills) will help reduce the inflammation so that the other medications can work. Never give your dog pain medications with steroids unless approved by your veterinarian — some dogs can develop fatal ulcers when these medications are combined.

Your veterinarian will want to recheck your dog's ears in 2-3 weeks to see how they are responding to the treatment. If inflammation persists, it is possible she will refer you to a veterinary dermatologist for further diagnostics and treatment. If the ear canals become calcified or overly thick, surgery may be required.