Ear Disease
April, 1997
A number of disease conditions can affect the canine ear. By
far, the most common is otitis externa, or inflammation of the
external ear canal. Although infection is nearly always present,
it is not a contagious disease. The organisms involved in the
infection can also be found in normal healthy ears. In otitis
externa cases, some underlying condition or change in the ear
allows these “normal” organisms to multiply and cause
infection.
Most ear ointments will reliably treat these infections, but in
cases of chronic or recurring infection, it is advisable to try
to identify the primary cause. Some underlying causes include:
excessive wax production, water in the ear canal, tumors in the
ear canal, foreign bodies such as plant material, ear mite
infestation, hypothyroidisms and allergies (food allergy, contact
allergy, and airborne allergies. After repeated bouts of
infection, some permanent changes can occur in the ear canal such
as thickening, swelling, and the formation of hyperplastic
nodules or lumps. These new permanent changes can further
predispose the ear to future infection, even if the initial cause
is identified and treated. Unfortunately, in a large number of
cases, no underlying cause can be found, and the dog needs to
undergo frequent ear cleaning and medicating for life.
Regardless of the cause, the signs of otitis externa are similar.
Common signs include head shaking, scratching the ears or rubbing
them on objects, on the floor or on the ground. Odor, discharge
and redness may also be seen. One side or both sides may be
involved.
Regardless of the cause, the initial treatment used is similar in
most cases. Topical treatment with an ointment or cream tends to
be cheaper and more effective than pills. Most ear medications
contain a number of ingredients such as antibacterials,
antifungals and anti-imflammatories. As previously mentioned,
most infections resolve completely or nearly so after 1-2 weeks
of this topical treatment. In the presence of large amounts of
wax or discharge, treatment is less successful and a thorough ear
cleaning is needed. Sometimes, this requires a sedative or
general anesthetic. In many cases of chronic otitis externa,
periodic cleaning of the ears, at home, with either mineral oil
or a commercial ear-cleaning solution is all that is needed to
decrease the frequency of infection. Your vet can discuss
products and demonstrate methods of removing dirt and excess wax
from the ear. After bathing, any water that remains in the ear
canal can predispose to infection, and it is therefore advisable
to dry the ear canal as well as possible.
In cases of chronic otitis externa that has led to permanent
anatomic changes previously mentioned, there are a number of
surgeries that can alter the ear canal to help with ventilation
or drainage or improve the ease of cleaning and medicating. In
the most severe cases, the entire ear canal can be removed. These
dogs undergo some permanent hearing loss, but the tissue that is
prone to frequent infections is no longer present.
Otitis media, inflammation and infection of the middle ear, is
much less common than otitis externa. It usually arises from
infection spreading from the external ear, through a ruptured ear
drum and into the middle ear. Although discomfort and itch
similar to otitis externa can be seen, otitis media can also
cause a head tilt and other equilibrium problems such as circling
or falling. Flushing can be accomplished, surgery can be helpful,
but treatment usually consists of oral antibiotics.
One fairly common problem that involves the ear flap and not the
ear canal is called an ear hematoma. This is a pocket of blood
and fluid that has leaked from blood vessels inside the ear flap.
It creates a soft swelling almost anywhere on the ear and may be
very very large. Surgical drainage is recommended for best
healing.
Hair loss and scabbing on the outside of the ear can be seen with
a number of different disorders, including allergies, scabies,
and ringworm. Ringworm is a fungal infection of the skin that can
be contagious to other animals and to people. It may occur on
various parts of the body, including the ears. Scabies or
sarcoptic mange, is a mite infestation that can also be spread to
people or other animals. It is diagnosed by a skin scraping and
can be treated using a parasiticide which was discussed in a
previous article, ivermectin.
Pemphigus is a rare autoimmune disease that can cause pustules
and other sores on the ears and other parts of the body and is
controlled with lifetime cortisone treatment.
Fly strike usually appears as dense accumulations of black debris
on the ear flaps. The skin underneath may be raw and bleed. The
ares can be protected with antibiotic ointment or petroleum
jelly. Gels containing insecticide or insect repellant may be
useful also.
Fortunately, most dogs will not develop any of the ear diseases
mentioned here and require minimal care to maintain healthy ears,
but for those individuals with a problem, seeking veterinary
attention early is a good idea.