Ear Infections

Introduction: Ear problems are among the most common reasons a pet is taken to a veterinarian. Infections of the ears can occur at any age and affect the ears of any type of dog. Dogs with large, droopy ears or hair-filled ear canals are more at risk. A lack of ventilation helps to produce the ideal environment for infections to flourish, and hair tends to impede the normal removal of debris and wax from the ear canal.

Causative Agents: Ear infections may be caused by bacteria, yeasts, mites, fleas, or ticks. Irritation of the ear canal by foreign material, such as grass or foxtails, can also produce ear infections by creating an environment in which these causative agents can flourish. Other conditions which commonly make a dog prone to ear infections include the physical conditions listed above (droopy ears with a lack of ventilation or hair-filled ear canals), excess moisture (common in dogs that like to swim - i.e. "swimmer’s ear"), allergies, hypothyroidism, dry scaly skin, ear tumors, and autoimmune diseases (pemphigus and lupus), or a combination of any of the above. Small numbers of bacteria and yeast can be found in normal ears.

Clinical Signs: At first, the animal may occasionally scratch at the ear or shake the head. As the problem progresses, the scratching and shaking become more intense. The dog may run with its ear pressed to the floor in an attempt to relieve the itching deep in the ear canal. Sometimes dark debris, blood, or a foul odor is noticed. In dogs with droopy ears, a rather common complication which is often noticed by the owner is a swelling of the pinna or "floppy part" of the ear. This swelling is called an aural hematoma and is usually self-inflicted by shaking the head or scratching the ear. The swollen area in the pinna is usually hot to the touch and extremely painful.

The area of the pinna outlined by the circle is a common place for an aural hematoma.

If an ear infection continues untreated, swelling of the inflamed tissues will cause the ear canal to narrow and further impede the outward movement of debris. Scar tissue will often replace the normal lining of the ear canal and may block the ear completely. Once this occurs, permanent hearing loss is common. The infection may spread to other structures and cause problems with the nerves of the face, balance problems, and pain when opening the mouth.

Disease Transmission: Ear infections are not usually regarded as contagious from one animal to another; however, drainage from a severely infected ear may be teeming with bacteria or other infectious agents. Any cut or open wound, inflamed tissue, or exposed mucosal surface such as the mouth or eye, can easily become infected if exposed to such infection-laden material.

Diagnosis: The diagnosis of an ear infection is relatively simple. The first step in diagnosing this problem is accomplished by visual inspection of the ear canal. An instrument known as an otoscope is generally used for this purpose. The otoscope is inserted in the ear canal and holds it open while a light illuminates the area. Some dogs will not tolerate this procedure while awake and may require sedation. If the ear canal is free of foreign objects or large amounts of debris, the veterinarian can assess any damage done to the ear drum located at the very end of the canal. Ticks, especially if engorged with blood, should be large enough to be seen and removed during the otoscopic examination. The next diagnostic step is to determine if an infection is present by taking a sample of any discharge and staining the sample on a glass microscope slide. This test is known as an ear cytology. See the pictures below. Yeasts, bacteria, and mites may be seen by microscopic examination. Some bacterial infections may need to be cultured in order to be successfully identified and treated.

Treatment: Treatment should address both the infection itself and the underlying cause. Therapy for the infection may involve flushing the ear while the dog is under anesthesia and/or administering antibiotics, anti-fungals, anti-parasitic drugs, and anti-inflammatory drugs. Specific therapy for infections should be based on ear cytology and/or culture. Certain ear medications should not be used if the ear drum is damaged; hence, the importance of the otoscopic examination.

Therapy for underlying causes depends on the specific cause identified and may involve regularly plucking hair from the ears and application of drying agents to reduce ear canal moisture. If a foreign object or small tumor is present, it can be removed and the infection may then be treated. However, if the underlying cause is a more involved condition such as an allergy, hypothyroidism, or pemphigus, successful treatment of the ear infection will rely greatly on the proper diagnosis and treatment of that condition.

Aural hematomas require specific surgical treatment to drain the swelling, followed by placement of sutures (stitches) to prevent recurrence.

This picture shows an ear where an aural hematoma has been drained and sutured.

If the ear canal is narrowed or blocked with scar tissue, successful medical treatment is unlikely. In some of these extreme cases, surgical intervention may be necessary. Complete removal of the ear canal (ear canal ablation) is a last-resort procedure, but it does remove the source of pain and irritation to the dog. Permanent deafness is an unfortunate result of the surgery; however, most of the dogs that require this surgery are already deaf.

Prevention: Good grooming, proper diet, and careful observation of a pet can help prevent this problem or at least catch it in the early stages. Keeping dogs that are prone to ear problems out of water can also be beneficial. If a problem is suspected, an examination by a veterinarian and subsequent therapy can help prevent a potentially serious and damaging situation.

This picture shows an otoscopic exam being performed on an anesthetized dog.


After the inner parts of the ear have been examined, a sample of the contents in the ear is often taken. This sample is stained and examined using a microscope looking for bacteria, yeasts, and fungi. This procedure is called ear cytology.