OTITIS EXTERNA (EAR INFECTIONS)
How common are ear infections in dogs?
Infection of the external ear canal (outer ear) by bacteria or yeast, is one
of the most common types of infections seen in dogs. It is called otitis externa.
Some breeds, particularly those with large or hairy ears like Cocker Spaniels,
Miniature Poodles or Old English Sheepdogs, seem more prone to ear infections,
but they can occur in any breed.
What are the symptoms of an ear infection?
A dog with an ear infection is uncomfortable and the ear canals are sensitive.
The dog shakes its head and scratches its ears trying to get the debris and
fluid out. The ears often become red and inflamed and develop an offensive odor.
A black or yellowish discharge commonly occurs.
Don't these symptoms usually suggest ear mites?
Ear mites can cause several of these symptoms, including a black discharge,
scratching, and head shaking. However, ear mite infections occur most commonly
in puppies. Ear mites in adult dogs occur most frequently after a puppy carrying
mites is introduced into the household. Sometimes, ear mites will create an
environment within the ear canal which leads to a secondary infection with bacteria
and yeast (fungus). By the time the dog is presented to the veterinary surgeon,
the mites may be gone, but a significant ear infection remains.
Since these symptoms are similar and usually mean an infection, can I not
just collect some medication?
There are several kinds of bacteria and at least one type of fungus which
might cause an ear infection. Without knowing the kind of infection present,
there is no way to know which medication to use. In some cases, the ear infection
may be caused by a foreign body or tumor in the ear canal. Treatment with medication
alone will not resolve these problems. Also, the dog must be examined to be
sure that the eardrum is intact. Administration of certain medications can result
in loss of hearing if the eardrum is ruptured. This determination is made by
your veterinary surgeon.
How do you know which drug to use?
First, the ear canal is examined with an otoscope, an instrument that provides
magnification and light. This permits a good view of the ear canal. This examination
allows us to determine whether the eardrum is intact and if there is any foreign
material in the canal. When a dog is in extreme pain and refuses to allow the
examination, it may be necessary to sedate or completely anaesthetize the dog
for a thorough examination.
The next step is to examine a sample of the material from the ear canal under
a microscope to determine which organism is causing the infection. Microscopic
examination is very important in helping the veterinary surgeon choose the right
medication to treat the inflamed ear canal. Further bacteriological examination
may also be necessary before treatment is started.
How are ear infections treated?
The results of the otoscopic examination and bacteriology usually determine
the course of treatment. If there is a foreign body or tick lodged in the ear
canal, the dog is sedated so that it can be removed. As stated previously, some
dogs have such a heavy buildup of debris that sedation is needed to cleanse
the canal and examine it completely. Cytologic study of debris from the ear
canal dictates which drug to use. Sometimes, it reveals the presence of more
than one type of infection (i.e., a bacterium and a fungus, or two kinds of
bacteria); this situation usually requires the use of multiple medications or
a broad-spectrum medication.
An important part of the evaluation of the patient is the identification of
underlying disease. Many dogs with chronic or recurrent ear infections have
allergies or low thyroid function (hypothyroidism). If underlying disease is
suspected, it must be diagnosed and treated, if at all possible. If this cannot
be done, the dog is less likely to have a favorable response to treatment. Also,
the dog might respond temporarily, but the infection will recur (usually when
ear medication is discontinued).
What is the prognosis?
Nearly all ear infections that are properly diagnosed and treated can be cured.
However, if an underlying cause remains unidentified and untreated, the outcome
will be less favorable Several examinations may be needed before the process
is completed and ultimate success can be expected.
How important is it to treat an ear infection?
Dogs with ear infections are miserable. Their ears are a source of constant
pain resulting in head shaking and scratching. However, that is not the only
problem. Head shaking and scratching can also cause broken blood vessels in
the ear flap, requiring surgery, and chronic ear infections can penetrate the
ear drum and result in an internal ear infection.
My dog's ear canal is nearly closed. Is that a problem?
Closing of the ear canal is another result of a chronic ear infection. There
are medications that can shrink the swollen tissues and open the canal in some
dogs. However, some cases will eventually require surgery.
What is the goal of surgery?
The surgery for a closed ear canal is called a lateral ear resection. The
goal of the surgery is to remove the vertical part of the ear canal and to remove
swollen tissue from the horizontal canal. Removing the vertical canal should
be successful, but removal of large amounts of tissue from the horizontal canal
is more difficult. In some cases, the ear canal is surgically removed which
may result in some permanent impairment of hearing.
Is there anything I need to know about getting medication in the ear?
It is important to get the medication into the horizontal part of the ear
canal. Be aware that the dog's external ear canal is "L" shaped. The vertical
canal connects with the outside of the ear; the horizontal canal lies deeper
in the canal and terminates at the eardrum.
The ear canal may be medicated by following these steps:
1. Gently pull the ear flap straight up and hold it with one hand.
2. Apply a small amount of medication into the vertical part of the ear canal
while continuing to keep the ear flap elevated. Hold this position long enough
for the medication to run down to the turn between the vertical and horizontal
3. Put one finger in front of and at the base of the ear flap, and put your
thumb behind and at the base.
4. Massage the ear canal between your finger and thumb. A squishing sound
tells you that the medication has gone into the horizontal canal.
5. Release the ear and let your dog shake its head. If the medication contains
a wax solvent, debris will be dissolved so it can be shaken out.
6. If a second medication is to be used, apply it in the same manner.
7. When all medications have been applied, clean the outer part of the ear
canal and the inside of the ear flap with cotton wool soaked in some of the
medication. Do not use cotton tipped applicators to do this as they tend to
push debris back into the vertical ear canal.
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