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Name
Ear Infections, Canine
Short Description
Otitis externa, otitis media, and otitis interna
Affected Animals: Dogs and cats. Cocker spaniels and other long-eared or
floppy-eared breeds may be more predisposed to developing
infections.
Overview: An ear infection, or otitis, is an inflammation
of the outer, middle, or inner ear canal. Most frequently, a dog
will develop otitis in the outer ear that may worsen and spread into
the middle ear. Once in the middle ear canal, the inflammation can
move into the inner ear -- or, in cases in which the otitis has
originated in the middle ear, the infection can instead progress
outward to the external ear.
Otitis can be caused by a tremendous array of factors, including
fleas, excess liquid in the ear from swimming, autoimmune diseases,
skin parasites, and excess wax production. Generally, dogs that
develop ear infections have reddened ears that are painful to the
touch and ooze a foul-smelling liquid. A punctured eardrum is not an
uncommon result of a middle ear infection, and the more severe cases
of otitis can lead to partial deafness, lack of balance, nausea and
vomiting, and problems with the nerves of the eye.
Clinical Signs: Clinical signs can vary depending on the severity
and location of the infection, but typical symptoms of otitis
include pain and erythema of the pinna, head shaking and scratching
of the ears, and purulent and malodorous exudate coming from the ear
canal. The animal may tilt the affected ear downwards and may roll
or lean to the affected side. If both sides are affected, the animal
may be deaf or ataxic. Some animals may be nauseated, vomit, and
have Horner's syndrome. Any neurological clinical signs indicate
significant middle ear or inner ear disease.
Symptoms: Ears that are red, painful to the touch, and
produce a foul-smelling discharge are symptomatic of otitis.
Typically, a dog with an ear infection will scratch and shake the
ears or may tilt the affected ear downwards. Animals that are
affected more severely may show some neurological signs such as
rolling or leaning to one side. If both ears are affected, the
animal may be deaf or off balance and uncoordinated. Some animals
may be nauseated and vomit. Also, some dogs may get a condition
called Horner's syndrome in which the pupils are sized differently
and the nictitating membrane is raised. This condition indicates
that a nerve has been affected by the inflammation from the middle
ear. Any neurological clinical signs indicate significant middle ear
or inner ear disease.
Description: Typically, ear infections begin with otitis
externa and then progress deeper into the canal to the middle ear.
When the inflammation in this region of the ear is chronic, the
eardrum may rupture and the infection may spread to the inner ear --
or, the infection may begin in the middle ear and progress outward
to the external ear. Of the three types of otitis, infections in the
inner ear are often the most severe and can lead to partial deafness
and neurological problems.
In serious cases of otitis, the skin begins to form into folds in
which the infection can become trapped, making cleaning and use of
topical treatments very difficult. In addition, in cases of otitis
interna, the skin will secrete more wax and debris that allows yeast
and bacteria to overgrow, causing further disease. Severe
inflammation leads to permanent skin thickening, mineralization, and
narrowing of the ear canals. Once this occurs, the only viable
treatment will be surgical removal of part or all of the ear canal.
Diagnosis: The veterinarian will make a diagnosis based on
the clinical signs, physical exam findings, and through the use of
several other diagnostic tools. One such tool is cytology, which
involves taking a swab of the ears and looking at the material
collected under a microscope for the presence of bacteria, yeast,
mites, and other substances that might cause an infection. Bacteria
and yeast are normally present in low numbers in all dogs' ears, but
a large presence will lead to an ear infection.
Skin biopsies may be needed to determine any diseases such as an
autoimmune disorder that could cause a skin abnormality affecting
the ear. Skin scrapings may be needed to detect mites, tiny
parasites that can infect the ears and cause skin diseases. X-rays
of the skull can be used to examine the middle and inner ear for
signs of disease. In addition, cultures of an infected ear help
determine the presence and type of bacteria, as well as antibiotics
that are appropriate for treatment. The majority of animals with ear
problems have such pain in their ears that they cannot withstand
having them examined, cleaned, cultured, or x-rayed without the use
of general anesthesia.
Prognosis: With proper treatment, otitis externa usually
will resolve within three to four weeks, although it may recur in
certain animals. The prognosis is good for otitis media and otitis
interna since medical treatment usually is effective. The key for
long-term success is correcting or treating the underlying problem
that led to the development of the otitis.
Transmission or Cause: Possible causes of otitis externa, which may lead
to infections of the middle and inner ear, include excess moisture
in the ears due to swimming or bathing; inappropriate treatment or
cleaning of the ears such as may be caused by the use of
cotton-tipped applicators; excess wax production in the ears; an
underlying disease; or a foreign body that is obstructing the ear
canal. Additionally, otitis externa can be caused by a host of
parasites, including ear mites, mange, fly bites, and fleas.
Allergies and illnesses such as autoimmune diseases may also lead to
otitis. The most common cause of the development of otitis media and
otitis interna is a bacterial infection resulting from otitis
externa.
Treatment: After the cause of the otitis has been diagnosed,
the veterinarian usually will perform a thorough cleaning of the ear
canals while the dog is under sedation or general anesthesia. The
use of topical medications, which are placed into the ear canal, is
often very beneficial in killing yeast, bacteria, and mites. Oral
medications also may be used in conjunction with other treatments to
help kill bacteria, yeast, and mites. The veterinarian will teach
the dog's owner how to clean and medicate the ears properly to
ensure successful treatment of otitis.
The surgical correction of the ear canals may be necessary in cases
of severe infection. One type of surgery, called a lateral ear canal
resection, allows the ear to drain more easily, decreases the amount
of humidity in the ear, and makes topical treatments easier to
apply. A total ear canal ablation -- a complete removal of the ear
canal -- is performed on dogs with severe, chronic ear disease that
is nonresponsive to medical therapy.
Prevention: Prevention is best accomplished when the
veterinarian is able to determine the underlying factors that can
lead to development of otitis. Proper cleaning of the ears is also
critical. A veterinarian can explain how to clean the ears, as well
as how to apply any medications that have been prescribed to treat
the otitis.
