Hearing checkup on a Labrador Retriever in vet ambulance.

Dog Ear Infections

Overview of Ear Infections in Dogs

Otitis externa, commonly referred to as an “ear infection,” is a condition characterized by inflammation of a dog’s external ear canal. It is particularly prevalent in dogs with long, floppy ears and is relatively uncommon in cats.

The underlying cause of otitis externa is usually started by a primary, undetected ailment, like allergies. The main allergies seen in dogs and cats that contribute to ear infections are atopy (environmental allergies), cutaneous adverse food reactions (food allergies), and flea allergies. Immune-mediated diseases and hormonal changes, like hypothyroidism, may also trigger recurrent ear infections. Less common primary triggers include parasites, such as ear mites, or foreign bodies, such as fox tails or tumors. Secondary causes are those things that cause an ear infection in an abnormal ear, like bacteria and yeast.

In addition to primary and secondary causes, there are predisposing factors that can make treatment harder or allow an infected environment to thrive. The most common predisposing factors in canine ear infections are: abnormal conformation of the ear canal, excessive moisture, mass or polyps blocking the ear canal, or systemic disease exacerbating the infection.

There are also perpetuating factors present in the ear canal that contribute to the presence of an infection. These can involve the eardrum, ear canal, or tissue lining the canal.

All of these factors need to be considered when evaluating a dog with ear infections and used to make the best treatment plan to minimize the occurrence of chronic infections. Using these four categories (primary & secondary causes and predisposing & perpetuating factors) is called the PSPP system.

Click here for more on the individual breakdown of these four categories.

Ear infections can occur in dogs of any age, breed, or sex.

Breeds with Predispositions

Dogs predisposed to otitis externa include those with genetic predispositions that make them more likely to develop ear infections.

Examples of some predisposed breeds due to abnormal ear canals include:

Examples of some predisposed breeds due to hair in their ears include:

Examples of some predisposed breeds due to pendulous pinnae include:

Other medical problems can lead to symptoms similar to those encountered in otitis externa. It is important to exclude these conditions before establishing a definite diagnosis.

Clinical Signs of Otitis Externa

Clinical symptoms of an ear infection include:

Diagnosis of Ear Infections in Dogs

Diagnosis of an ear infection is strongly based on physical examination and clinical signs, in addition to a complete medical history to evaluate for trends or predisposing factors.

Complete medical history is useful to look for patterns and to rule out other underlying health conditions. Dogs with otitis externa can sometimes have seasonality associated with flare ups. Seasonal flare ups are seen more commonly with environmental allergies. Year-round clinical signs may point more to generalized allergies (atopy) or food allergies. A complete medical history should include other underlying or previous medical conditions, as this could help in determining underlying causes. In this medical history, the list of current medications and previous medications is extremely helpful.

Physical Examination

A physical examination is used to evaluate the entire dog, as well as examine their external ears. Your veterinarian will pay close attention to the size of the ear canal, the presence of pain, the smell of both ears, the presence of hair or foreign material, masses or polyps, the character of discharge/exudates, soundness of the eardrum, and general health. An otoscope is used to look in the external ear canal. If performing an otitic exam is painful, sedation may be required.

An ear cytology is used to identify parasites, yeast organisms, bacteria, and cellular components. This test will help to determine the cause of otitis externa and choose the proper treatment for your dog. Cytology involves taking a swab of the ear discharge, which is then spread onto a slide and evaluated under a microscope.

Culture and sensitivity tests are used in cases of recurrent infections, as there are some organisms that are resistant to many antibiotics. In these cases, a sample of debris from the ear canal is collected before cleaning or application of ear medications and is sent out to a laboratory for further antibiotic sensitivity testing.

Blood and Skin Testing

Full blood work is often not recommended or needed for simple and non-recurrent ear infections. Blood work is useful in complicated or recurrent cases to rule out other underlying causes. A complete blood count (CBC) is conducted to evaluate your dog for other problems, such as infections or inflammations. Serum biochemistry tests are used if there are other abnormal symptoms on the physical examination, such as weight loss. More advanced blood work to look at endocrine function is also helpful.

Thyroid level blood tests determine the presence of hypothyroidism, which is the most common endocrine disorder that causes otitis externa in dogs. Adrenal function tests are used to rule out Cushing’s disease, which is hyperadrenocorticism secondary to excessive pituitary secretion of adrenocorticotropic hormone. Dogs with hyperadrenocorticism are predisposed to developing ear infections.

If other skin disease is present in addition to an ear infection, further testing may be recommended. Additional tests may include a skin scrape to look for parasites. This is a good diagnostic tool to diagnose Demodex mites. A cytology of the skin can help to look for bacterial skin infections (pyoderma).

Diagnosis of Severe Cases

For severe cases, additional imaging such as radiographs, CT scans, or video otoscopy may be recommended. Using these different imaging techniques, the veterinarian is able to evaluate the ear canal and look for deep infections, masses/polyps, or foreign material. Video otoscopy is helpful in the management of chronic otitis cases. With video otoscopy, veterinarians are able to visualize the horizontal and vertical ear canals in real time, in addition to the tympanic membrane. Vets can also remove foreign material if present, lavage/flush the ear canal, take sterile samples for cultures, and biopsy masses/polyps if present.

Your veterinarian may suggest a referral to a dermatologist in difficult or recurrent cases, or additional diagnostic tests to exclude or diagnose other conditions or better understand the impact of otitis externa on your dog. During this visit, the dermatologist may discuss available allergy testing options.

Treatment of Otitis Externa

Treatment of otitis externa involves treating the primary disease process and the underlying factors that predispose the dog to infection.

Initial management includes cleaning your dog’s ears. This can be accomplished by placing solutions in your dog’s ears at home or by having them cleaned by your veterinarian. Moderate to severe infections may require sedation and in-hospital flushing. Flushing debris from the canal is critical prior to topical treatment. There are several types of ear cleaners, so make sure your veterinarian chooses one that is best for your dog. Avoid over-the-counter ear cleaners, as they could exacerbate irritation. Ear cleaning should be done once or twice daily until all debris is removed, which typically takes 3 to 7 days. Excessive cleaning should be avoided, since cleaning solutions keep the ear moist and more susceptible to infection if overused.

Topical Treatment

Topical therapy usually consists of placing ear medication in your dog’s ear one to two times daily. The specific medicine will depend on the cause of the infection. It is extremely important to follow your veterinarian’s directions on applying the medication in your dog’s ear. Improper medication and improper administration is a common cause of treatment failure. Uncomplicated ear infections respond well to topical ear medications such as Antimax, Otomax, Surolan, Panalog, Osurnia, Claro, and Mometamax.

Systemic Treatment

Systemic therapy with glucocorticoids, such a prednisone, may be given to decrease pain and inflammation, since these hormones are often used as inflammatory agents. Topical glucocorticoids can also be used. These medications should only be given if prescribed by a veterinarian, as they can have interactions with other medications.

Systemic antibiotic therapy may be indicated with severe bacterial infections or if concerned about otitis media or interna (a deeper ear infection). Antibiotics may be chosen based on cytology and/or bacterial culture. Antifungal therapy is indicated in cases of severe recurrent yeast infections.

Many therapies extend for 1 to 2 weeks beyond clinical signs. Regular follow-up visits to your veterinarian are important to ensure that your dog’s condition does not worsen. Always recheck with your veterinarian if the ear infection is failing to get better or worsens at any point.

If underlying systemic disease or endocrine problems are noted on initial diagnostics, the treatment plan should involve addressing these in addition to treatment of the ear infection.

If a mass or polyp is noted, additional surgery or treatments may be indicated based on the biopsy report and severity of disease. These recommendations will be individualized for your dog based on their condition.

Follow-up Treatment

Optimal treatment for your dog requires a combination of home and professional veterinary care.

Follow-up can be critical, and it often includes the following recommendations:

Home Care and Prevention

Optimal treatment requires a combination of home and professional veterinary care. Be sure to have your veterinarian or their staff show you how to place medication into your dog’s ears. Do not use cotton swabs in the ear, since these can push infection and/or discharge deeper into the ear canal. Clean the ears before applying medication.

Special care at home can help maintain healthy ears. Dry the ears after bathing or swimming and check ears for foreign matter. Also, at the first sign of scratching, head shaking, pain, swelling, odor, or discharge, have your dog’s ears checked by your veterinarian. The earlier the treatment is initiated, the sooner medications can be started and your dog can find some relief.