Otitis externa is inflammation of the external ear canal. It is often called swimmer's ear as repeated water exposure makes the ear canal vulnerable. Symptoms include redness and swelling of the ear canal. It is diagnosed through history, physical exam, and microscopic examination of ear debris. Treatment involves cleaning the ear canal and applying ear medications like antibiotics, antifungals, or insecticides depending on the cause. Regular cleaning and follow up with a veterinarian can help prevent recurrences.

1. Otitis externa
Prof. Magda M. A. Omar
magdaali70@aun.edu.eg
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Magda M. Omar/ Assiut

2. Otitis externa
• Otitis externa is a condition that causes inflammation
(redness and swelling) of the external ear canal, which is
the tube between the outer ear and eardrum.
• Otitis externa is often referred to as "swimmer's ear"
because repeated exposure to water can make the ear canal
more vulnerable to inflammation.
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Magda M. Omar/ Assiut

3. What is the normal anatomy of the ear?
A dog’s ear has three major sections:
• The outer ear: This area of the ear consists of the ear flap (called a pinna) that
funnels sound into the ear canal, a narrow L-shaped tube that travels to the deeper
parts of the ear. The L-shaped canal is often referred to as having a vertical section
and a horizontal one.
• The middle ear: The middle ear starts where the outer ear ends – at the level of the
eardrum (called the tympanic membrane), a fragile membrane that can be easily
damaged by disease. The middle ear is made of three small bones (called ossicles),
an air-filled cavity (called a bulla) and a tube that leads from the bulla to the
mouth (called the auditory or Eustachian tube).
• The inner ear: The inner ear connects to the brain and contains nerves that help
with hearing and balance.
•
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6. Etiology
Predisposing factors:
• The narrow L-shaped anatomy of the ear canal allows for accumulation of secretions
deep inside it. With swelling from inflammation and infection, narrowing of the canal is
augmented and secretions can’t escape. Furthermore certain breeds, including Pugs,
English Bulldogs, and Shar Peis, have a twist in the external ear canal that can
completely occlude this tube when marked inflammation is present.
• Other predisposing factors including swimming, humidity, elevated ambient
temperature, and trauma to the ear canal caused by inappropriate hair plucking and
overly aggressive cleaning.
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Magda M. Omar/ Assiut

7. Primary causes
• Hormone disorders
• Flea allergies
• Environmental allergies (called atopic
dermatitis or atopy)
• Immune-mediated diseases (i.e.:
pemphigus foliaceus)
• Certain genetic/hereditary disorders
(i.e.: keratinization disorders)
• Ear mites
• Ticks
• Food allergies
• Foreign objects (i.e.: grass awns)
• Polyps
• Tumors
These are factors that directly cause inflammation in the outer ear, and include:
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Magda M. Omar/ Assiut

8. Otitis Externa – How is it diagnosed?
• A veterinarian will employ a 3-pronged approach to the diagnosis of otitis
externa:
• Obtaining a thorough patient history
• Performing a complete physical examination, including comprehensive ear
and skin evaluations
• Using microscopy to look at cells and debris from the ear canal (called
cytology)
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Magda M. Omar/ Assiut

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Magda M. Omar/ Assiut

10. Treatment
• Treatment is usually by a dual regimen of ear cleaning and ear medication. Ear cleaning
should be demonstrated by a veterinarian, due to the risk of pushing infected material
deeper into the ear hole.
• The aim of cleaning is to remove any byproducts of the infection which lead to further
irritation and discomfort, and may be in turn, causes of further infection. Good care
often involves cleaning the ear daily, to prevent build-up and bring the infection under
control.
• Ear medications are applied after cleaning and drying, and is usually in the form of ear
drops or ointment applied daily or twice daily for one or two weeks. The type of
infection must be identified by the veterinarian by examining a sample of
ear exudate under a microscope, since bacterial infection will only respond to antibiotics,
fungal infection to a fungicide, and ear mites to an insecticide.
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Magda M. Omar/ Assiut

11. Specifics of treatment
• In mild cases, a product with anti-inflammatory, anti-fungal and anti-bacterial
ingredients are often employed. In more severe cases, ear cleaning under sedation or
anesthesia may be required and evaluation for otitis media may be indicated. Treatment
for ear mites include ear drops that contain Pyrethrins or an avermectin such as
ivermectin or selamectin.
• Cleaning of the ears is very important for treatment of ear infections. Home remedy
cleansing and antiseptic mixtures are good
• In some recipes, Betadine is added as well. Some natural ear cleaners may slightly lower
the pH levels in dogs' ears, making the ear less susceptible to recurring infections.
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Magda M. Omar/ Assiut

12. Prevention
• The best way to avoid ear infections is to clean your dog’s ears on a regular basis, on
average about once a month. Your dog’s ears should always be cleaned anytime the ears
have come into contact with water, such as after bathing, swimming or playing in the
snow. Water in the ear canal creates a moist environment that is ideal for yeast and
bacteria to grow. Certain breeds of dogs are more prone to ear infections based on the
conformation of their ears and the amount of hair in the ear canal. Some will require
regular hair plucking inside the ears to ensure that the canal can breathe to help reduce
the chance of infection. Ear infections can also be caused by other factors such as
allergies. It is important to always follow up with your veterinarian to allow them to
track the frequency and severity of reoccurring ear infections and ensure your pet gets
the proper treatment.
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19. https://www.youtube.com/watch?v=brCwQftfJ0o&feature=emb_logo
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