Ear Infections

Ear disease, one of the most common conditions seen in veterinary medicine affects approximately 15-20% of all canine patients and 6-7% of all feline patients. The term otitis externa refers to an inflammation of the external ear canals, whereas otitis media refers to middle ear disease, and otitis interna is a disease of the internal ear. It is vital to understand the underlying mechanisms of ear disease and to direct treatment at all of the contributing factors in an effort to effectively treat and resolve these complications. Because there are so many components to ear disease, it is easier to categorize them into primary, predisposing, and perpetuating causes.

Because the external ear canal is lined with skin, any disease that affects skin can also cause abnormalities in the ear canal. Primary causes of ear disease are conditions which by themselves can cause inflammation in the ear canal. Some of these include parasite infestations (such as Otodectes earmites or demodex mites), allergies (to food or environmental allergens such as pollen or dust), foreign material in the ear canal (such as plant material or buildup of cerumen/wax), hormonal diseases (such as low thyroid), autoimmune skin diseases, and ear canal tumors or polyps.
Predisposing factors of ear disease are those that change the climate within the ear, allowing for inflammation or infection to easily develop in animals with a pre-existing primary disease.
Anatomical variability between breeds is one of the most common predisposing factors. Narrowed ear canals or excessive ear folds (ex. Shar Peis and Bulldogs) can trap moisture, wax and debris, which prevent the body’s ability to rid those components. . Excessive moisture in the ears from swimming or bathing can promote inflammation as well. Trauma to the ear canal, such as using Q tips or irritating topical substances, may also harm the ear canal lining.
Perpetuating factors include anything that prevents normal and prompt resolution of ear disease. These factors are not the reason for the initial onset of disease, but need to be addressed before healing is possible. The most common perpetuating factors for chronic otitis are secondary bacterial or yeast ear infections. A common misconception is that bacterial or yeast infections are a cause of chronic or recurrent ear disease. In fact, these infections are only possible because of underlying primary factors. It is imperative to keep this in mind as our job should not end with just ridding the ear of secondary infections but identifying and treating the underlying cause of the infections so that they stop recurring.
Another potential perpetuating factor is caused, ironically, by the treatments themselves. Some animals may develop contact reactions to topical medications. Overmedicating can also be problematic as the excess medication keeps the skin of the ear canals wet and ulcerated, ultimately preventing or slowing the healing process. On the other hand, under medicating may not rid the ear of organisms or adequately treat inflammation. Inappropriate use of antimicrobial drugs is also detrimental. For example, treating a yeast ear infection with an antibiotic (meant for bacteria) will not cure the infection and may do more harm than good. Hence, the importance of performing cytology (microscopic examination of ear debris) on both ears ear each time a pet is presented for a possible infection. Not only does this enable identification of the organism(s) present (bacteria, yeast or both) but it aids the doctor in choosing which type of medication is appropriate for your pet.
Another common, but unfortunately under diagnosed perpetuator of external ear disease is otitis media, or middle ear disease. Otitis media is present in up to half of all dogs with chronic otitis externa and needs to be addressed before external ear disease can be resolved.
Lastly, when ear infections become very chronic, ear canal scarring, narrowing and even calcification (hardening into bone) can occur, making it even more difficult and sometimes impossible (in cases of ear canal calcification) to clear ear infections and resolve ear canal inflammation.
The only way to resolve chronic or recurrent ear disease is to identify and address all of the primary, predisposing, and perpetuating factors. This means that in addition to the direct medication of the ears, we need to treat any underlying causes such as allergies, parasites, endocrine disorders, immune-mediated diseases, or other conditions, as is determined for each specific patient. Allergy testing or a hypoallergenic diet trial may be needed to identify underlying allergies. Blood testing may help investigate hormonal abnormalities. Skin biopsies may be needed to determine any diseases such as an autoimmune disorder that could cause a skin abnormality affecting the ear. Skin scrapings may be needed to detect mites, tiny parasites that can infect the ears and cause skin diseases. X-rays of the skull or CT scan can be used to examine the middle and inner ear for signs of disease. In addition, cultures of an infected ear help determine the presence and type of bacteria, as well as antibiotics that are appropriate for treatment. Treatment of secondary ear infections involves ear flushing and cleaning to remove exudate and wax, and topical +/- oral antibiotics to treat the infections.
Cleaning the Ears
Cleaning the external ear canal is absolutely imperative for two reasons. First, topical medications need to come into contact with the skin of the ear canal. If the lining of the ear canal is covered by inflammatory byproducts, wax, or old dried medications, this necessary medication contact cannot happen. Second, it is essential to evaluate the eardrum in order to successfully treat the disease. The eardrum is the only thing separating the external ear from the middle ear, and if it is not intact there will be middle ear disease as well. Because treating the middle ear involves different methods, we must know if middle ear disease is present. In addition, some medications we put into the external ear canal are not safe to use in the middle ear and, therefore cannot be used if the integrity of the eardrum is unknown. But, if we are assured of an intact structure, we are able to use whichever drug best fits the external ear disease.
In mild cases of external ear disease, cleaning may be possible in the awake patient. Ear flushing may happen in the hospital during the appointment, and cleaning usually needs to happen at home as well. A specific cleaner will be prescribed based on the doctor’s findings, and there will be instructions as to the frequency required. It is critical to use only the cleaner recommended by the doctor.
To clean the ears, lift the flap of the ear up firmly to straighten out the ear canal. Squeeze the liquid into the ear canal to fill it until it is overflowing. (Do not allow the tip of the ear cleaner bottle to contact the ear canal, as the bottle can become contaminated with bacteria. If the tip of the bottle touches the ear canal, then it is important in this case to clean the tip of the bottle well with rubbing alcohol after use). Still holding the ear flap, with your other hand massage the cartilage of the ear canal so that you hear squishing. Do this for at least 15-20 seconds. Then you may release the ear and let your pet shake his or her head. You may clean the inside of the ear with a tissue or cotton balls but NEVER insert cotton swabs out of sight. Repeat as necessary so that after shaking there is no visible matter coming out of the ears. This is a messy process so prepare your house or do cleaning outside. When using medication in conjunction with cleaning, medicate 20 minutes after cleaning.
In moderate or severe cases it is necessary to anesthetize the patient and perform a deep ear flushing. This is often the only way to remove tenacious inflammatory material, and old medications, and clean the crevices made by inflamed tissues. See the Video-otoscopy section of our “Services” website tab for pictures and videos of this procedure.
Medicating the Ears
Almost all cases of external ear disease require topical medication. The type used is prescribed based on the results of physical examination, cytology, and/or culture. Commonly used medications include anti-inflammatories, antibacterial, and antifungal components. Depending on the case, topical medications are usually continued for 2-6 weeks. If cleaning the ears is part of your pet’s treatment plan, it is important to instill the medication 20 minutes after cleaning.
Systemic Medications
Some patients with ear disease require systemic (oral or injectable) medications in conjunction with topical therapy. These may include steroids or nonsteroidal anti-inflammatories to reduce ear canal swelling and itching, antibacterial or antifungal drugs to address infections, or analgesics to manage pain. Animals with otitis media or otitis interna may need 1-3 months of systemic antibiotics
Surgery
There are some cases of ear disease that require surgical intervention. Some polyps and tumors can be removed with a simple surgical procedure. More complicated surgery is necessary for the more invasive growths, in cases of middle ear disease where proper application of medicine is not physically possible, or when irreversible changes within the ear are present secondary to longstanding disease. The decision to undergo surgery is made only after determining the inability to reverse changes within the ear and ear canal as a result of chronic inflammation and ear infection using less invasive therapies.
Re-evaluations
Regular and timely recheck examinations are crucial. The environment of the ear can change rapidly once treatment has been initiated, and as specific disease processes go through the transformation of healing, medications must be adjusted. It is only through diligent monitoring that we are able to maximize the chance of resolution.
Ear disease is complicated and can be frustrating for doctors, owners, and patients. The key to successful treatment is teamwork, dedication, and perseverance.

In taking the first step towards addressing ear disease the doctor must first perform a thorough physical examination while paying close attention to the quality of your pet’s skin and coat. Many times, the ability to detect these subtle hints upon complete examination may be crucial in providing the necessary clues to determine the primary cause of your pet’s ear disease. The next step is a thorough otoscopic examination of the ear. Without actually attaining complete visualization of the ear canal and eardrum, including microscopic evaluation of samples collected from deep within the ear, comprehensive and appropriate treatment of the ear disease cannot be effectively accomplished.
A complete examination of the ear canals and eardrums of both dogs and cats can often be extremely frustrating and provide a source of discomfort to any pet that is experiencing any form of ear disease. Simply manipulating the ear to aid the insertion of the otoscope cone into the canal of a pet with a painful ear can often exacerbate the pain and often result in aggression toward the veterinarian or staff. It is often after experiences such as this that many pets become extremely reluctant to allow even their owners to treat their ears at home. This, in turn, perpetuates the chronic ear disease that unfortunately extends the animal’s suffering while left untreated. Because appropriate corrective treatment of diseased ears can only be done after a complete examination and evaluation, the use of sedation or anesthesia is often required for patients experiencing discomfort. Often in severe or chronic cases, the presence of swelling along with the accumulation of inflammatory material, such as mucus and pus within the canals may prevent complete examination. In these particular cases, very inflamed ears may need to be treated with topical or oral steroids for a week or two in an effort to gain better visualization of the ear at the following recheck exam.
It is imperative to perform a microscopic evaluation of the secretions collected from deep within the ear canal when trying to identify a patient’s current condition, including underlying causes. Performing cytology of both ears each time your pet is presented for an exam due to possible ear disease is ideal and necessary so that we can identify what kind of infectious organisms are present, if any. With this information, we can tailor treatment to each individual patient to resolve the issue in an effective manner. It is also essential to recheck the cytology of the ears during treatment so as to monitor progress. In doing so, we are able to ensure that no changes to the treatment protocol need to be made and assess response to the chosen treatment. It is important to monitor populations of organisms during treatment, as change can occur which may require the use of different medications. A culture of these organisms is also needed in some cases in order to determine susceptibility and resistance to drugs if there is no favorable response to the previously chosen medication(s). In order to obtain these samples in painful pets, sedation or anesthesia may be necessary in some cases.
After determining the underlying disease affecting the ears, a thorough ear cleaning must be performed. Adequate evaluation of the skin of the canals and the status of the ear drum can only be done after all the accumulated material has been evacuated. It is important that the medication(s) the pet is being treated with, actually be able to reach all affected tissue of the complete external canal and ear drum for resolution of infection, inflammation, or both. In most cases cleaning at home by owners can be initiated to begin with. If the material in the canals is persistent despite ear cleanings at home, or if the patient is too painful for this type of cleaning, then an ear flush under anesthesia with the use of an otoendoscope is necessary in order to completely remove the debris from the ears.
The ear drum is very thin, and is what separates the external ear from the middle ear. It is essential to evaluate the integrity of the ear drum, especially when managing ear disease. Middle ear disease can be quite serious, and the treatment approach implemented is entirely different from that taken with external ear disease.
Radiographs (x-rays) are often necessary to determine the presence of middle ear disease. Because of the precise positioning needed to acquire these views, anesthesia is always necessary, even in the most cooperative of patients. Radiographs are often performed at the time of deep ear flushing to avoid an additional anesthetic procedure. Occasionally, advanced imaging such as computer tomography (CT) or magnetic resonance imaging (MRI) is needed in order to evaluate the severity of ear disease with regard to the skull and surrounding tissues.
One of the most critical aspects to the resolution of ear disease is regular re-evaluation, especially with patients that have perpetual triggers that lead to ear disease such as an overproduction of cerumen (wax) leading to build-up and eventually a foreign body. Multiple recheck examinations along with cytologic sampling are needed in every case of ear disease. The more complicated or chronic cases may require more than one deep flushing and follow-up radiograph.
Ear disease is complicated and can be frustrating for doctors, owners, and patients. The key to successful treatment is teamwork, dedication, and perseverance.

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