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.

T H E E A R

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 (also called the auricle)

• 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.

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

AnvilThe 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)