Presentation – Ear Infections
Maren von der Heyde , NBS 2012
This very important body part
of our German Shepherd is –
when it comes to cleanliness –
the most neglected.
THE
EAR
Healthy
Inner Ear
This is what we see the most at shows
External Otitis primarily in younger dogs
Chronic Allergic Otitis - This is the second most common
ear problem we see in older dogs
The Ear is divided into three
portions:
• The External Ear
• The Middle Ear
• The Inner Ear
Ear structure in relation to the
dog’s head
What is the General Structure of the Ear?
The external ear consists of:
•
The prominent earflap or pinna
•
The pinna is a funnel-shaped
structure that collects sound
and directs it into the external
ear canal.
•
The pinna is covered by skin,
and the outer or posterior
aspect is covered by fur.
•
Numerous
muscles
are
attached to the curved
cartilage located between the
inner and outer layers of skin
around the ear, and these
muscles allow the pinna to
move and twitch.
(also called the auricle)
The external ear continued:
• The external ear canal
(also called the
auditory canal or
meatus).
•
The external ear canal
extends from the base
of the pinna downward
and inward towards
the eardrum (also
called the tympanic
membrane).
• .
The external ear continued:
• The external ear canal
is L-shaped, with the L
lying on its side. The
canal forms an almost
90-degree angle
between its two
sections:
• The short vertical
outer section and
the longer
horizontal inner
section
The middle ear consists of:
• The middle ear includes the ear drum and the bony
tympanic cavity (osseous bulla) which lies just past
the ear drum.
• Within this tympanic cavity we find the auditory
ossicles – three tiny bones that vibrate when
stimulated by sound waves.
• These ossicles are named the malleus, stapes and
incus (commonly known as the hammer, the stirrup
and the anvil because of their resemblance to
these objects).
Middle Ear
Auditory Ossicles
Middle ear continued:
• These three bones form a chain across the middle
ear from the tympanum to the oval window of the
inner ear.
• The middle ear is connected to the back of the
throat (pharynx) by the auditory or eustachian
tube. This tube allows air from the pharynx to pass in
and out of the middle ear, which helps keep middle
ear pressure normal
• The middle ear is connected to the inner ear
through the oval window, which lies against the
stapes bone.
The Inner Ear
• The inner ear is located within the petrous temporal
bone of the skull and consists of two parts.
• The osseous or bony labyrinth houses a series of thin,
fluid-filled membranes called the labyrinth.
• The inner ear contains three distinct structures:
•
•
•
•
•
•
the cochlea (spiral tube),
vestibule,
and
three semicircular canals.
Petrous Temporal Bone
Petrous
Temporal Bone
The Inner Ear
Hammer
Anvil
The Stirrup
The Inner Ear continued:
• The cochlea contains the nerves that transmit the
electrical impulses and is directly responsible for
hearing.
• The vestibule and semicircular canals are
responsible for maintaining balance or equilibrium.
• These tissues are supplied by the two branches of
the 8th cranial nerve (the vestiblocochlear nerve),
which transmits electrical impulses related to sound
and balance back to the brain.
What are the Functions of the
Ear?
• The two main functions of the ear are:
• to detect sound
• and
• allow for hearing, and to maintain
balance.
Hearing
• Sound first enters the external ear canal as sound
waves. As these waves strike the ear drum, it begins
to vibrate.
• These vibrations are then transmitted to the three
small bones of the middle ear (the malleus, incus
and stapes), which amplify the sound vibration.
• The end of the stapes is connected to the oval
window of the inner ear. As the stapes vibrate, it
transmits the sound vibrations to the cochlea, the
snail shaped portion of the inner ear, which
transforms the vibrations into nerve signals that are
transmitted to the brain where they are interpreted
as sound.
Hearing
• Dogs can hear as low as 16 Hz and they
can hear as high as 105,000. The average
range for people is betwen 63 and 23,000
and the average range for dogs is 67
and 45,000.
• They can also hear faster, as they can
pick up sound in as little as 1/16th
hundredth of a second. The ability to
hear sound does vary among breeds and
does change according to age.
Hearing continued
• Dogs have 15 different muscles in their
ears that enable them to move in all
directions and detect sounds from
wherever they come. They respond to
higher pitched sounds. If you speak to
your pet in a higher pitch, you are sure to
get their attention. Your dog will listen
carefully to what you are saying. They
can also distinguish between sounds that
humans may think are identical.
Balance
• The other function of the ear is to help maintain
balance.
• The three semicircular canals of the inner ear are
oriented at right angles to each other.
• When the head turns, the resulting movement of
fluid in these canals allows the brain to detect
which way and how much the head is turning.
• Another part of the inner ear responds to gravity
and sends information to the brain when the head
is held still in a stationary position.
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.
Middle Ear Infection
Middle Ear Infection
Overview continued:
• 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.
Otitis Media
• Otitis
media
is
an
under
diagnosed condition in pets,
reportedly occurring in association
with acute otitis externa in 16% of
dogs and with chronic otitis
externa in more than 50%.
Ear Infections
• Source and Cause(s)
• There are many reasons for your dog’s ear to
become infected, however with a middle or
inner ear infection it is usually the result of an
outer ear infection that has moved further in
the ear.
Some More Images of Ear
Infections
Ear Infections
• Some of the most common causes for an
external ear infection are the following:
• Allergies, including food allergy
• Parasites such as ear mites
• Presence of bacteria and/or yeast and a
certain type of fungus
• Foreign bodies such as a plant fiber
• Trauma
• Excessive moisture present in the ear;
especially when swimming often
Adverse reaction to food can
develop acute external otitis
Yeast Otitis
(Malassezia)
Bacterial Otitis
Ear Mites
•
•
Ear mites are tiny external
parasites that live in your pet’s
ear canal. Otodectes cyanotis,
otherwise known as ear mites,
are
very
contagious
little
creatures. The adult mites can
live up to 2 months in your pet’s
ear contently feeding on ear
wax and skin oils.
If you think your pet may have
mites bring him/her to your
Veterinarian
to
get
them
checked out. The best way to
diagnose this parasite is by
having your Veterinarian take
an ear swab from your pet’s
ears. They will then look under
the microscope and if your pet
has mites this is what they will
look like:
Ear Mites
Images of Ear Mites in Dogs Ears
Ear Mites
Ear mites
Ear Infection
• Signs and Symptoms
• The most common signs and symptoms of
an ear infection are the following:
• Foul odour present in the ear(s)
• Scratching or rubbing the ears and head
• Discharge in the ears (yellow,green or white)
• Redness or swelling of the ear flap or canal
• Excessive shaking of the head or tilting it to
one side
Ear Infections
• Signs and Symptoms continued:
• Pain around the ears and head
• Depression
• Aggressive behaviour when head and
ears are touched
• Loss of balance while walking or standing
• Circling to one side
• Head tilt
• Drooping or facial features on the
effected side
Diagnoses of Otitis Externa
•
•
•
•
• is straight forward:
Head shaking,
scratching at the ear,
visual redness of some portion of the
ear surface odour and/or
discharge eminating from the ear.
Diagnosis of Otitis Media and
Otitis Interna
• Is more difficult but can be
accomplished via otoscopy (if
tympanic membrane is ruptured,
discolored or bulges)
• Radiographs (the tympanic bullae can
be evaluated)
• Myringotomy (obtaining material from
middle ear by passing instruments
through the tympanic membrane
In addition to afore-mentioned
findings:
• If the history consists of persistent ear
inflammation (at least 6 months in
duration), there is a 90% probability
that both otitis externa and otitis
media are present
Treatment
• Treatment varies depending on the
severity of the disease. In mild
infections, oral or injectable antibiotics
in combination with topical antibiotics
and antifungal agents are often used.
• In more severe and chronic cases, the
ear drum may need to be surgically
incised and the middle ear flushed
and treated.
Treatment continued:
• In some cases, more invasive surgery
including removal of part of the bony
covering of the ear (bulla) through a
lateral or ventral bully osteotomy may
need to be performed.
• In very severe cases, complete
removal and closure of the entire ear
canal (total ear ablation) may be
necessary.
Treatment continued:
• In cases where tumors, allergies, or
other factors contribute to the cause
of the infection, they must also be
properly identified and treated for the
entire treatment to be successful.
Treatment
• Ear Mites
• Thorough cleaning of ear canal
• Topical Treatments:
• Topical insecticide instilled once or twice daily for up to 14
days
• Topical mineral oil preparations
• Systemic Treatments:
• Ivermectin (Ivomec 1%)
• Dosage based on weight of dog but never more than 10ml
• Administered subcutaneously or orally every 10 to 14 days
for a total of two to three applications
Treatment continued:
• Ear Mites
• Selamectin (Revolution) is topically applied
insecticide that kills fleas and various species of
mites, including Otodectus cyanotis as well as
acting as a Heartworm preventative. Though
applied topically, it is absorbed systemically.
• Fipronil (Frontline Top Spot)
• a topically–applied insecticide marketed for flea
and tick control. It has demonstrated miticidal
activity – it is neither marketed nor approved for this
purpose. The medication remains in the oils and oil
glands of the skin. Mites that contact the host
animal’s skin will be killed and thus will not
reproduce.
Prevention
• While not all middle and inner ear
problems can be prevented, the vast
majority of them can.
• Early diagnoses and prompt treatment of
the more common outer ear infections
will prevent most middle and inner ear
infections.
• Controlling ear mites and allergies, along
with good routine ear cleaning and care
are the key to preventing all ear
infections.
Ear Cleaning
• Can be accomplished with the
following supplies:
• Ear wash solution
• Cotton balls
• A tweezers or hemostat to pluck hair
• Q tips may be used if used properly
Ear cleaning continued:
• Ear cleaning solutions contain various
chemicals and may contain drying
agents. Check with your veterinarian
regarding which product to use and
how often to use it.
• Excessive ear cleaning can be
damaging to the ear
Cleaning Supplies
DO NOT stick q tips into the ear any
further than you can see
References
• Newman Veterinary Medical Services
• Washington State University – College
of Veterinary Medicines
• Dr Natalie Rouget - Halfway House
Veterinary Clinic (for kindly letting me
have the ear skeleton)