Otitis externa, commonly referred to as an ear infection, is inflammation of the external (outer) ear canal. While infection plays a role in the process, it is usually not the primary cause. Instead, a combination of predisposing factors such as long, floppy ears; primary factors such as allergies; and perpetuating factors such as bacterial and yeast infections lead to this condition in dogs. Treatment of otitis externa involves identifying and controlling the primary factors and treating the perpetuating factors.
Common name: Ear infection
Scientific name: Otitis externa
Certain breeds have predisposing factors that increase their chances of developing otitis externa. These breeds include Labrador retrievers, cocker spaniels, springer spaniels, chow chows, poodles, basset hounds, English bulldogs and shar-peis. This condition can occur in all breeds, ages and genders of dogs.
The incidence of ear infections in dogs is 4 to 20 percent.
Warm and humid environments can contribute to this condition.
Clinical signs (primary, most to least frequent, scientific term, synonyms)
Erythematous (red) ear canals, Swollen or thickened ear canals, Painful and/or pruritic (itchy) ears, Discharge from ears (often with a foul odor), Head shaking.
Clinical signs (secondary, most to least frequent, scientific term, synonyms)
Aural hematoma (blood filled swelling of the pinna or ear flap), Head tilt, Aggression secondary to painful ears.
Causes (scientific, common term)
Predisposing factors, Long, floppy ears, Narrow ear canals, Increased hair and glandular secretions in the ear canals, Frequent bathing and swimming, Incorrect cleaning methods, Primary factors, Allergies, Parasites, Foreign material, Abnormal immune systems, Systemic diseases, Growths in the ear canal , Perpetuating factors, Bacterial infections, Yeast infections, Chronic inflammation, Treatment errors.
Organ systems affected (most to least affected)
Otoscopic exam: ear exam with a cone, light source and magnification, Otic (ear) cytology: microscopic examination of the discharge to look for parasites, yeast, bacteria and cells, Bacterial culture, Blood test for systemic diseases, Allergy test, Complicated cases may require additional tests.
Otitis media (inflammation of the middle ear), Otitis interna (inflammation of the inner ear), Trauma.
Otitis externa, commonly referred to as an ear infection, is inflammation of the external (outer) ear canal. While infection plays a role in the process, it is usually not the primary cause. Instead, a combination of predisposing factors, primary factors, and perpetuating factors lead to this condition in dogs.
Predisposing factors are breed characteristics and lifestyles that make dogs more likely to develop this condition. Long, floppy ears; narrow ear canals; and increased hair and glandular secretions in the ear canals predispose certain breeds. Some examples are Labrador retrievers, cocker spaniels, springer spaniels, chow chows, poodles, basset hounds, English bulldogs, and shar-peis.
In addition, frequent bathing and swimming and incorrect cleaning methods can contribute to the development of this condition. Primary factors are the underlying causes of the inflammation. The most common cause in dogs is allergies.
Environmental allergens, food and topical medications can be the triggers. Parasites such as ear mites and ticks, foreign material in the ear canal, systemic diseases, and growths can also be primary factors. Perpetuating factors prolong and increase the severity of otitis externa. These include bacterial and yeast infections, chronic inflammatory changes in the ears, and treatment errors. Bacteria and yeast are normally found in the ears; however, the predisposing and primary factors allow for an environment in which they can overgrow, leading to infection.
Signs of otitis externa may include red, swollen (or thickened) painful and itchy ears. There is often a foul smelling discharge from the ear canals. Pain and itching may cause excessive scratching and head shaking, decreased interaction, and, possibly, increased aggression.
Veterinary care is necessary to determine the cause and appropriate treatments. It is important to follow home cleaning and medicating instructions. Monitor for reactions to medications.
Diagnosis and management of otitis externa begins with a thorough physical and otic (ear) examination. The veterinarian may examine the discharge from the ears under a microscope to look for parasites, yeast, bacteria and cells. In recurrent cases or cases of severe bacterial overgrowth, the vet may culture the discharge to determine the type of bacteria and the best choice of antibiotic treatment. Blood and allergy tests may be performed to identify possible primary factors.
Once identified, primary factors can be treated or controlled to reduce or prevent the recurrence of signs. Topical and possibly oral medications containing antibiotics, antifungals and steroids may be prescribed along with ear cleaners to treat the perpetuating factors. In severe cases, surgery may be necessary.
It is important to see the veterinarian if your dog has signs of otitis externa. You may want to request a demonstration of proper cleaning and medicating techniques. This condition can become more severe if left untreated and may lead to chronic pain and hearing loss. Identifying and treating the primary cause is essential, and, in some cases, consulting a veterinary dermatologist is helpful in the management of otitis externa.
The outcome of otitis externa is favorable with treatment. Some dogs require long-term therapy.
Logas, D, Bellah, J. Diseases of the External Ear and Pinna. In: Morgan, RV, Bright, RM, Swartout, SM, Handbook of Small Animal Practice, 4th Ed. Philadelphia: Elsevier Science, 2003; 1049-1054.
Medleau, L, Hnilica, KA. Otitis Externa. In: Medleau, L, Knilica, KA, Small Animal Dermatology, A Color Atlas and Therapeutic Guide. Philadelphia: W.B. Saunders Company, 2001; 276-283.
Radlinsky, MG, Mason, DE. Diseases of the Ear. In: Ettinger, SJ, Feldman, EC, Textbook of Veterinary Internal Medicine, 6th Ed. St. Louis: Elsevier Saunders, 2005; 1171-1180.
Colette Wegenast, DVM
Steven Hansen, DVM, MS, MBA, DABVT, DABT
© 2007. The American Society for the Prevention of Cruelty to Animals (ASPCA)