Ear Canal Infection (Bacterial Otitis Externa) in Cats
Bacterial infections in the ear canal are frequently caused by scratches to
the skin or cat bites. Some begin in an ear canal that contains
excessive amounts of wax, cellular debris, or foreign material. Ear mite
infections are often the cause of bacterial otitis.
Signs of an infected ear canal are shaking the head, scratching at the
affected ear, and an unpleasant odor. The cat may tilt or carry her head down
on the painful side and exhibit tenderness when the ear is touched. Examination
reveals redness and swelling of the skin folds of the ear canal. There may be
an excess amount of wax or a purulent discharge. There is often an unpleasant
odor associated with the discharge.
Some cats are born without the
ability to hear because of developmental defects in the hearing apparatus. Cats
may also be deaf in just one ear. Congenital deafness occurs most often in
white cats with blue eyes, and is the result of an incomplete autosomal
dominant gene. However, not all cats with blue eyes are deaf, and that includes
not all white cats with blue eyes. Longhaired cats with blue eyes have a higher
risk of deafness than shorthaired cats with blue eyes. White cats with the
An otoscope is needed to examine the deeper portions of the ear canal and
look for a foreign body or other cause of chronic infection. This is best left
to a qualified professional-your veterinarian or a veterinary technician.
Bacterial infections that progress over a long period produce thickening and
reddening of the ear canal with considerable discomfort and pain. Treatment is
prolonged. Inflammatory polyps and tumorlike masses may develop and block the
ear passages. Surgery then becomes necessary to open the ear and promote
Treatment: The first step is to determine the cause. Mild cases-those
without excessive discharge but perhaps associated with a dirty ear or the
buildup of wax-may be treated at home after they have been diagnosed by a
Remove crusts and serum with a cotton ball soaked in an ear-cleaning
solution obtained from your veterinarian, being careful not to push the debris
deeper into the canal. If there is a buildup of wax, instill a special
wax-dissolving agent to soften the debris and make it easier to remove.
Afterward, dry the ear canals with a cloth or cotton ball and apply an
antibiotic ear medication.
If the ear is extremely painful, you may need to leave your cat at the
veterinary clinic for sedation and a thorough cleaning. A swab of the discharge
may be examined under the microscope to look for the cause of the problem.
Also, your veterinarian may take a sample for a culture and sensitivity test,
especially if your cat has recurrent infections, to determine the best choice
of antibiotic therapy. Some cats will need oral antibiotics as well
as topical ones.
Clip the cat’s nails to minimize injuries from scratching at the ear.
Yeast of Fungal Otitis Externa
The prolonged use of topical antibiotics alters the natural bacterial flora
in the ear canal, which improves conditions for the growth of yeast and fungi.
A yeast otitis may therefore develop as a secondary problem in a cat with a
long-standing bacterial or ear mite infection, or a food allergy. Malassezia pachydermatis is the most common
culprit, including in cases of otitis related to food allergies and atopy.