A good ear exam is necessary for diagnosing otitis in dogs and cats

Ask your average small animal vet what problem area they see the most, and you’ll probably hear, “Ears.” And, while dogs are most commonly treated for problem ears, similar problems affect cats, too. What is it about ears that make them so prone to disease and what can owners and their vets do about it?

First, it’s important to have some vocabulary so we can be precise about ear problems. The ear flap (which actually stands up on cats and some dogs) is called the “pinna.” The tube that leads from the pinna toward the eardrum is the “canal.” The eardrum is sometimes called a “tympanum” or “tympanic membrane.” Normal discharge from the ear is “cerumen.” An infection or inflammation on the pinna side of the tympanum is “otitis externa.” If it affects the little bones and nerves just on the other side of the tympanum, it’s “otitis media.” And, rarely, we see the infection move further toward the brain into the region responsible for balance; this is “otitis interna.” By far, otitis externa is the most frequently seen type of ear problem in the cat and dog.

Causes and Risk Factors: In otitis externa, the infection itself may be bacterial, fungal (yeast), or both; it may also be an infestation of ear mites. Many possible factors can lead to infection: a foreign body (often a foxtail), prolonged wetness from swimming, cleaning with cotton swabs, etc. For organisms to flourish, the environment is usually humid and warm, with little ventilation. Some dogs are more prone creating such an environment due to the narrow shape of their ear canals, floppy pinnas, increased hair in and around the canal, a polyp or tumor in the canal, or their love of swimming. Some health problems, such as seasonal allergy, food allergy, hypothyroidism, seborrhea, or immune compromise can also predispose an animal to otitis.

Clinical Signs: The owner will likely notice an odor, the dog shaking its head or scratching at its ears, a hematoma on the pinna, or a brown discharge in the ear canal. If the infection has advanced to otitis media, the pet’s head might droop and there might be limited lip or ear movement on the affected side. The pet might also drool. If infections have been recurrent and severe, the lining of the canal might become very thickened, sometimes to the point of closing the canal; some chronic changes cannot be reversed.

Diagnosis: For otitis externa and most cases of otitis media, diagnosis is made based on history, clinical signs, and an ear exam. The vet uses a lighted otoscope with a cone that allows visualization of the entire canal, providing the condition of the canal allows it; in cases where the discharge is too great or the canal is narrowed by inflammation or other changes, initial treatment might precede a full exam. Depending on the pain associated with the infection and the temperament of the dog, sedation or general anesthesia may be required for this exam.

The vet will likely take a sample of the discharge and view it on a microscope slide to see whether to treat for mites, bacteria, and/or yeast. In cases of recurrent infection, the vet might look to a culture of the discharge to identify uncommon bacteria. If otitis media is suspected but the tympanum is not intact or cannot be seen, a CT scan can give good information about the situation.

Treatment: With otitis, treatment is based on several factors: whether the infection is simple or recurrent/chronic, whether it involves mites, whether permanent changes have occurred in the ear canal, and what parts of the ear are affected. For a case of simple otitis externa in a pet, the treatment is typically cleaning with a gentle solution followed by a week or two of topical antibiotic/antifungal medication. If ear mites are involved, a miticide will be given in the clinic, with another one given a few weeks later to kill larvae that hatched in the interim. For pets that are seen frequently for otitis, the vet might opt for systemic antibiotics in addition to the topical ones, and steroids to reduce inflammation. Finally, in those dogs at high risk for otitis externa and media that are seen frequently with severe infections, the ear canals and the middle ear can be treated surgically; this is a radical treatment that leaves the pet deaf in the affected ear – but it is sometimes used as a last-ditch attempt at reducing pain.

Prevention: For low-risk animals, little can be done to prevent an ear infection. For high-risk pets, some risk factors can be minimized: treating underlying health problems, clipping hair around the ear and plucking the hair in the canal, using a drying solution after swimming, and cleaning the ears as directed by the vet (and avoiding aggressive cleaning with swabs).

When prevention fails, early intervention is important in making sure a small infection doesn’t become a big problem.