Dr. Debra Primovic
Otitis externa, commonly referred to as an "ear infection", is an ear condition characterized by inflammation of the external ear canal. It is particularly prevalent in dogs with long, floppy ears. Ear infections represent one of the top 10 reasons dogs present to veterinarians and may affect up to 20 percent of dogs.
Infections are caused by fungus, bacteria or parasites. Laboratory tests can help to determine the underlying cause of the infection.
Several factors may predispose dogs to ear infections, including:
• Long floppy ears
• Abnormal ear conformation or anatomy
• Water or hair in the ears
• Foreign material in the ears
• Autoimmune disease
• Generalized skin disease
Ear infections can occur in dogs of any age, breed or sex. Dogs predisposed to otitis externa include those with genetic predispositions to abnormally-shaped ear canals, such as the Chinese Shar-pei, Chow Chows, and English bulldogs; breeds with hair in the ears like Poodles and some Terriers; dogs with pendulous, long-hanging ear flaps (pinnae) such as the Cocker Spaniel, Springer Spaniel, and Basset Hounds; or outside and working dogs that are exposed to water or foreign bodies. Infections are most common in humid environments or during the summer months.
What to Watch For
Common signs of an infection include:
• Scratching or rubbing the ears
• Head shaking
• An abnormal odor or discharge from the ear
• Pain when you manipulate the ear
• Redness and swelling of the external ear canal and/or ear flap
Veterinary care should include diagnostic tests to determine the underlying cause and help guide subsequent treatment recommendations. Tests are needed to confirm the diagnosis of otitis externa and exclude other diseases that may cause similar symptoms. The following diagnostic tests are often recommended:
• Complete medical history and physical examination with special attention to the ears and skin. Your veterinarian will also pay close attention to the size of the ear canal, presence of pain, smell of ears, presence of hair in the ear canal, or foreign material, growths or polyps, character of any discharge, soundness of the ear drum, and general health. Your pet may need to be sedated for this type of exam to be properly completed.
• Cytology, which involves taking a sample of the ear discharge or any growths and examining it under a microscope. 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 pet. Cytology usually involves taking a swab of the ear discharge. The character of the discharge can sometimes be associated as follows: Dark black discharge can be associated with ear mites; brown or grey discharge can be associated with yeast infections; and white-yellow-green colored discharge can be associated with bacterial infections.
• Culture and sensitivity. This procedure involves taking a sample of the ear discharge and sending it to a laboratory to identify the specific bacteria present. The bacteria are then exposed to multiple antibiotic samples to determine what will kill them most effectively.
• Radiographs (X-rays) to determine the health of the ear canal and bone and to evaluate the extent of involvement.
• Biopsy of growths to determine the presence of tumors.
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 to better understand the impact of otitis externa on your pet. These tests are selected on a case-by-case basis and may include:
• Complete blood count (CBC) and serum biochemical profile to check for factors that may contribute to the infection as well as to determine if a concurrent disease is present.
• Skin scraping tests may be recommended to determine the presence of parasites or mites.
• Allergy tests to determine if your pet is allergic to things that may irritate the ears, in addition to the skin.
• Urinalysis to evaluate the kidneys and bladder.
• Thyroid tests to determine the presence of hypothyroidism, which is the most common endocrine disorder that can lead to otitis externa in dogs.
• Adrenal function tests to rule out Cushing's disease, which is also known as hyperadrenocorticism.
• Dietary trial to rule out allergic disease.
• Fungal cultures in the presence of severe or recurrent fungal infections.
Treatment of otitis externa involves treatment of the primary disease process, recognition and treatment of the underlying factors that predispose the pet to infection, and treatment of the specific infectious agent. Treatments for otitis externa may include the following:
• Cleaning the ear. This can be accomplished by placing solutions in your pet's ear at home or by having the ears cleaned by your veterinarian. Moderate to severe infections may require sedation and in-hospital flushing. Your veterinarian can show you how to properly clean the ears at home if you are willing to try.
• Topical therapy. It usually consists of an ear medication that you place in your pet's ear once or twice daily. The specific medicine and directions will depend on the cause of the infection. It is extremely important to follow your veterinarian's directions carefully. Improper medication and improper administration is a common cause for treatment failure.
• Systemic therapy (usually given by mouth or in an injection) with glucocorticoids, such as prednisone, may be given to decrease pain and inflammation. These are hormones often used as anti-inflammatory agents.
• Antibiotic therapy may be indicated in cases of severe bacterial infection or ulceration. Antibiotics can be chosen based on cytology and/or bacterial culture.
• Antifungal therapy in cases of severe or recurrent yeast infections. Drugs used may include Ketoconazole (Nizoral®), Itraconazole (Sporanox®) or Fluconazole (Diflucan®) for 2 to 4 weeks. Yeast infections in the ear canal can take much longer to treat than bacterial infections.
• Anti-allergy therapy.
• Regular follow-up visits to your veterinarian are important to ensure that your pet's condition does not worsen.
• Administer prescribed medications as directed and be certain to contact your veterinarian if you are experiencing problems treating your pet.
• Long term maintenance cleaning may be recommended in cases of long-standing infection. Cleaning procedures can be daily or weekly depending on the rate of wax and debris formation.
• Schedule regular veterinary visits to monitor your pet's condition.
• Periodic ear evaluations with cytology may be recommended.
• Additional ear cultures may be useful in long-standing infections.
Of course, the precise follow-up depends on the severity of your pet's disease, response to therapy and your veterinarian's recommendations.
Home Care and Prevention
Optimal treatment requires a combination of home and professional veterinary care. Follow-up evaluations can be critical. Be sure to have your veterinarian or his/her staff show you how to place medication into your pet's ears.
• Do not use cotton swabs in the ear; these may push infection and/or discharge deeper into the ear canal. Clean the ears before applying medication.
• Return to your veterinarian for follow-up examinations as suggested.
At home, special care of your pet's ears can help to 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 pet's ears checked by your veterinarian.
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. Examples are:
• Atopy. Fifty-five percent of dogs with this itchy skin disease caused by an allergy also have otitis externa.
• Autoimmune disease, such as systemic or discoid lupus erythematosus or pemphigus
• Contact allergy
• Demodicosis (Demodectic Mange)
• Endocrine (hormonal) imbalance
• Food allergy
• Foreign bodies such as foxtail awns or other plant material
• Parasites like ear mites, which are responsible for 10 percent of otitis externa in dogs
• Sebaceous adenitis (inflammation of the sebaceous glands in the ear canal)
• Seborrhea (an oily and/or scaly skin disorder)
• Tumors. The following have been reported: squamous cell carcinoma (more common in cats than dogs), histiocytomas, sebaceous gland adenomas, adenocarcinomas, basal cell tumors, mast cell tumors, chondromas, chondrosarcomas, trichoepitheliomas, apocrine gland adenomas, fibromas, fibrosarcomas, and papillomas (warts).
• Zinc-responsive dermatosis
Adapted from: http://www.petplace.com/dogs/otitis-externa-in-dogs/page1.aspx Hopefully, you won't ever have to deal with an ear infection in your dog or cat. However, the percentages are such that the odds are against you and you will get your chance to face this problem. And, if you do, this information will give you your best chance to succeed.
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~~The goal of this blog is to provide general information and advice to help you be a better pet owner and to have a more rewarding relationship with your pet. This blog does not intend to replace the professional one-on-one care your pet receives from a practicing veterinarian. When in doubt about your pet's health, always visit a veterinarian.~~