Module 6: Otitis Externa and Media (Week 7) Flashcards by Kianelys Heredia

Definition:
Is cone-shaped and articulates with the chain of three bones called the auditory ossicles

Tympanic Membrane

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Definition:
- Acute or chronic inflammation of the external ear canal
- May involve the pinna

Otitis externa

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Definition:
Inflammation of the middle ear

Otitis media

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What is the most common ear disease in dogs and cats?

Otitis externa
- 10 to 20% dog
- 2 to 10% cat

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Functions:
- Collect sound waves
- Conduct sound waves to the tympanic membrane
- Determine the origin of the sound waves

External Ear Functions

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(T/F) Both ears have to function to know the direction of sound

True

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External Ear Canals: Composed of 2 Elastic Cartilage
- Expands to form pinna, funnel-shaped

Auricular

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External Ear Canals: Composed of 2 Elastic Cartilage
- Fits within base of auricular, overlaps osseous external auditory meatus; flexibility

Annular
- dogs can move their pinna

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External Ear Canal:
What is the notch between the Tragus laterally and Antitragus causally called?

Intertragic incisure
- This is the perfect place to place your otoscope for looking at the ear

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(T/F) The external ear canals have microbiome

True
- Bacteria
- Staphylococci
- Micrococcus spp. (the only normal one)
- Beta-streptococcus
- Corynebacterium spp.
can also become pathogens
- Malassezia pachydermatis

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External Ear Canals:
- Superficial
- Ducts open into the hair follicle

Sebaceous glands

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External Ear Canal:
- Simple, coiled tubular glands
- Modified apocrine glands
- Located in the deeper dermis below the sebaceous glands
- Ducts open into either the hair follicle or onto the surface of the external ear canal

Ceruminous glands

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External Ear Canals:
- Emulsion that coats the ear canal
- Desquamated keratinized epithelial cells, glandular secretions
- Removal by epithelial migration

Cerumen

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Tympanic membrane
Auditory ossicles (3)
Tympanic cavity
Eustachian tube (auditory tube) (equalize pressure)

The Middle Ear

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Histologically:
- Outer and inner epithelium
- Core of collagen
- Hairless, glandless
45 angle to center
Pars flaccid (dorsal part)
Pars tensa (ventral part)
- Semitransparent
- Stria mallearis
- Concave due to tension

Tympanic Membrane

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(T/F) Bulging pars flaccida indicates otitis media

False, it does NOT indicate otitis media except in CKCS dogs

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Epitympanic recess
Ventral tympanic cavity
Tympanic cavity proper
Round window
Oval window
Eustachian Tube

Tympanic Cavity

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Microbiome
- Negative ear cultures in 50% of the ear swabs
- Organisms isolated in positive ear cultures
  - yeast, E. coli, Staphylococcus spp., Corynebacterium spp, Streptococcus sp.

Middle Ear

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Divided by a septum into 2 separate tympanic cavities; connected through a foramen between the septum and petrous bone
Dorsolateral (smaller of the two)
- Auditory ossicles, ostium of auditory tube, tympanic membrane
Ventromedial
- Air-filled tympanic bulla

Feline Middle Ear

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Middle Ear:
Incomplete bulla septum

Dog

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Middle Ear:
Complete bulla septum

Cat

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Housed in a bony labyrinth
Vestibule
Semicircular canals
Cochlea
Bony surrounds membranous labyrinth

Inner Ear

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Inner ear:
- Housed in the petrous temporal bone
- Bony labyrinth
- “Snail shell”
- Oval and round windows

Cochlea

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Inner Ear: Cochlea
- Follows shape of the bony labyrinth
- Three ducts:
- Scala vestibulisuperior
- Scala media (cochlear duct) - medial
- Scala tympani-inferior

Membranous labyrinth
important for exam

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List the Cochlea Membranes:

- Reissner's membrane - Floor of scala vestibuli - Roof of scala media (cochlear duct) - Basilar membrane

List the TWO fluids of the Cochlea:

1. Perilymph - Scala vestibuli - Scala tympani 2. Endolymph - Scala media

Inner ear: Cochlea - Stria vascularis - Blood vessels - *Endolymph*

Spiral ligament-outer wall

- Tectorial Membrane - Reticular lamina - Hair cells - *Inner hair cells* (1 row) - *Outer hair cells* (3 rows) - Supporting cells - *Stereocilia* - *Tectorial membrane* - *Basilar membrane*

Organ of Corti

Hair Cells: - Actual receptor cells for hearing

Inner Hair Cells (IHC)

Hair cells: - Important role in adjusting the tuning and sensitivity of the IHC

OHCs - most susceptible to damage

Auditory System: - Determined by *rate of action potentials firing*

Intensity

Auditory System: - Determined by part of the *Organ of Corti* that is stimulated

Frequency

Auditory System: - Determined by higher central auditory nervous centers comparing sounds from *both ears*

Location

- Connects cochlea with brainstem - Relay information about the intensity, frequency, and timing of a sound - Part of CN VIII (vestibulocochlear nerve) - Course from the cochlea through a small canal in petrous temporal bone: internal auditory meatus (IAM)

Auditory Nerve

- CANS (central auditory nervous system) - Cochlear nucleus (CN) - Connects to SOC - Superior Olivary Complex (SOC) - Connects to IC thru LL - Lateral Lemniscus (LL) - Inferior Colliculus (IC) - Connects to medial geniculate body - Medial Geniculate Body (MGB) - Connects to auditory cortex - Auditory Cortex

Auditory System

Hearing Loss: - Wax accumulation/Stenosis/Hyperplasia (otitis externa) - Infectious otitis media, PSOM - Medications (ointments, packing) - Mass/polyp

Conductive

Hearing Loss: - Congenital hereditary deafness - Dalmatians - Drugs - Noise-induced hearing loss - Presbycusis

Sensorineural

Which hair cell is the actual receptor cell for hearing?

Inner hair cells (IHC)

Etiology of Otitis - The Three P's

- Facilitate the inflammation by permitting alteration of normal microenvironment - Establishment of secondary infections

Predisposing Factors for Otitis Externa

List the Conformation predisposing factors for otitis externa:

- Stenotic ear canals - Chinese Shar Pei - Overgrowth of bacteria, yeast - Inhibit proper cleaning of ear - Hair in the canal - Impair ventilation - Impair clearance - Routine removal is *not* recommended - Pendulous pinnae - Restrict airflow - Higher risk for the development of OE

List the predisposing factors for Otitis externa:

- Conformation - Moisture - Maceration of *stratum corneum* - Secondary infection - Swimming, bathing - Inappropriate Therapy - Cotton Swabs (Q-tips) - Plucking hair - Irritant ear-cleaning solution - Improper topical antibiotic usage

- Conditions or disorders that initiate the inflammatory process - Epithelium of the ear canal is just an *extension of the rest of the body* - Most cases of otitis are associated with an underlying dermatologic condition

Primary Causes of Otitis Externa

List the Primary causes of Otitis Externa:

- Otodectes cynotis - Most common parasite - Life cycle *completed on host* - Irritate ceruminous glands - Diagnosis - Demodicosis - Demodex canis/Demodex cati - Infrequent cause of otitis external - Ceruminous otitis externa - Foreign Bodies - Plant material - Acute - Unilateral - Painful - Perforation of tympanic membrane - Atopic Dermatitis - Bilateral pruritic otitis externa - Otitis may be the only clinical sign in 10% of atopic dogs - Early: pinna - Later: erythema, infections - Cutaneous adverse food reactions - Bilateral pruritic otitis externa - Otitis may be the only presenting sign in 25% of food allergic dogs - Clinical signs similar to atopic - History, steroid response, age - Contact allergy - Rare - Non-haired portion of skin - May be caused by *topical medications* - Should be suspected if otitis fails to respond or worsens - Autoimmune Diseases (less common) - Pemphigus foliaceus

Primary Causes of Otitis Externa: What is the *most common cause of recurrent otitis externa in the dog*?

Allergic Diseases (>90%)

Puppies: Primary Causes of Otitis Externa - Affects puppies 3-16 weeks old - Etiology unknown - *Papules, pustules, alopecia, swelling* - *Submandibular lymphadenopathy* - Systemic illness

Juvenile Cellulitis

Primary Causes of Otitis: *Sebaceous adenitis* is a disorder of ______________

keratinization

Primary Causes of Otitis Externa: What are endocrine disorders that we see?

- *Hypo*thyroidism - *Hyper*adrenocorticism

Primary Causes of Otitis Externa: What are the most common cases of ear tumors?

- Ceruminal gland adenoma - Adenocarcinoma - More common in dog - Felines are usually malignant *unilateral most common*

Primary Causes of Otitis Externa: Polyps ...

- Feline nasopharyngeal polyps - Common - Purulent, ceruminous OE - Dysphagia, sinusitis - Inflammatory aural polyps -- *Canine* - *Rare*

Tips for Work-up of Primary Causes:

- Age of onset - Young animal: might be ear mites - Older animal: Neoplasia - Species: - Dog: CAFR, AD - Cat: Otodectes, polyp, allergic disease - Additional body affected - CAFR, AD - Hypothyroidism, hyperadrenocorticism - Juvenile cellulitis - Autoimmune diseases - Keratinization disorders

Tips for Work-up of Primary Causes: - Otodectes - CAFR, AD - Foreign body - Tumor/polyp

Ears only

Tips for Work-up of Primary Causes: - Foreign body - Tumor/polyp - CAFR, AD

Unilateral

- Sustain and aggravate the inflammatory process - Prevents resolution or worsens an already present otitis externa

Perpetuating Factors of Otitis Externa

List the Perpetuating Factors of Otitis externa:

- Bacteria - Coccoid bacteria - *Staphylococcus pseudintermedius* - Rod bacteria - *Pseudomonas aeruginosa* - > 4 cocci/OIF considered abnormal - *ALL* rod bacteria considered abnormal - Yeast - Malassezia pachydermatis - Candida spp. - >4/OIF considered abnormal - Progressive pathologic changes (end-stage ear) - Edema - Stenosis - Epidermal hyperplasia - Fibrosis - Calcification - TOTAL EAR CANAL ABLATION - Otitis media - Route of infection: - A direct extension of otitis externa through a ruptured tympanic membrane - Intact tympanic membrane does not rule out - Through Eustachian tube

- Dogs with *chronic recurrent otitis externa* - *89% had otitis media * - Intact tympanic membrane 73% - Dogs with acute otitis externa - 16% had otitis media

Otitis Media - Bacteria - Staphylococcus pseudintermedius, Pseudomonas aeruginosa (rod) - Yeast alone isolated in 23.7% of ears - Trauma, polyps, neoplasms, foreign bodies

Primary Secretory Otitis Media (PSOM) - Cavalier King Charles Spaniels - Head and neck scratching, neurological signs, hearing loss - Intact tympanic membrane, mucoid exudate

Non-Infectious Otitis Media

Clinical signs & Diagnosis

What is the most common clinical sign for infectious otitis media?

Recurrent Otitis Externa

List other Clinical signs for Otitis Media:

- Facial Nerve Paralysis - Drooping of ear/lip - Drooling saliva - Absent palpebral reflex - Keratoconjuctivitis sicca

Clinical sign for Otitis Media: - Injury to *sympathetic nerve* - *Ptosis* - Drooping of the upper lid - *Miosis* - Contraction of pupil - *Enophthalmos* - Backward displacement of eyeball into the orbit - Protrusion of nictitating membrane

Horner's Syndrome

List the clinical signs for Otitis Interna:

- *Horizontal nystagmus* away from the lesion - Head tilt, falling, rolling to the affected side - Asymmetric ataxia

How would you want to place the dog for an ear x-ray (views)?

- Rostralventral-caudodorsal - Lateral Oblique (L&R) - Dorsoventral

- Imaging method that uses x-rays to create pictures of cross-sections of body - Better for *bone* - Accuracy of CT and radiographs for diagnosis of otitis media are similar - CT appears to be more *sensitive indicator*

Computed Tomography (CT) - prefered for middle ear disease

- Allows distinction of soft-tissue components - Normal bulla: signal void - Fluid in bulla: - Hyperintense of T2-weighted

Magnetic Resonance Imaging (MRI)

Definition: Far-field recording of neuroelectrical activity of the auditory nerve and BS pathways in response to a sound stimulus

Brain-stem Auditory Evoked (BAER) Testing

Generator Sites: Distal auditory nerve

Wave I

Generator Sites: Proximal auditory nerve

Wave II

Generator Sites: Cochlear nucleus

Wave III

Generator Sites: Nucleus of the lateral lemniscus (LL)

Wave IV

Generator Sites: Inferior colliculus (IC)

Wave V

What is a *Site-of-Lesion diagnostic Toll*?

BAER Applications - Example: Neural lesions of CN VIII, Brainstem (Wave III)

Otic exam and flush

Otic exam

Otic Exam

The pars flaccida is located ...

dorsally

What occupies the remainder of the membrane and has radiating strands ?

Pars tensa

- Elbow shape structure

Stria mallearis

Otic Flushing: In Hospital How will you prepare ear for cleaning?

- Topical and/or systemic *glucocorticoids* if stenotic, hyperplastic, ulcerated - 2 to 3 weeks - 1 mg/kg q 24h, then taper after the flush - *Bloodwork* - Schedule ear flush

- General anesthesia, endotracheal tube - Radiographic imaging - CT - Cytology, culture - Ten minute soak with *ceruminolytic agent* - Flush using saline (warm) and bulb syringe - Final flush with saline, 8 Fr urinary catheter or red rubber feeding tube, 12 cc syringe, through otoscope - Visualization of tympanic membrane - Samples from middle ear for bacterial C/S and cytology if tympanic membrane is ruptured - Final flush with saline, Tom cat catheter/5French catheter, 12 cc syringe - If tympanic membrane intact, but abnormal, decision to perform myringotomy - not all patients get *myringotomy*

Otic Flushing: In hospital

List the Purpose/indication of a Myringotomy procedure:

- Samples - Remove exudates - Drain middle ear - Treat middle ear

- Visualization of the tympanic membrane - Incision made into the caudoventral quadrant - Cytology, C/S - Flush middle ear

Myringotomy procedure

Otic Flushing: In hospital List the possible complications (cats vs. dogs) for a Myringotomy:

- Facial nerve paralysis - Horner's Syndrome - Vestibular disturbances - Deafness (very rare in dogs, common in cats) - Healing of tympanic membrane - 21 to 35 days

Otic Treatments: Part 1

What is the treatment of Otitis? Infection: - Otitis externa - Otitis media = *NO OITMENTS/NO SUSPENSIONS* - Panolog oitment - Otomax - No ear Packs

Topical therapy (antimicrobial agents) - Appropriate volume; frequency *important*

What is the treatment of Otitis? Infection: - Otitis media - Severe otitis externa - also in the tissue of the ear canal

Systemic therapy (antimicrobial agents)

What is the treatment of Otitis? - Inflammation, proliferation, stenosis

Topical steroids

List the *Topical therapy* otic treatments:

- Ceruminolytic agents - Cleaning and drying agents - Glucocorticoids - Antiseptics - Antimicrobial agents - Antiparasiticidal agents

List the *Systemic* therapy otic treatments:

- GC - Antibiotics - Antifungals - Antiparasiticidals

Treatment of Otitis: - Apply 10 minutes prior to cleaning - *Contraindicates* with ruptured tympanic membrane - Most are *ototoxic*

Ceruminolytic Agents

Ceruminolytic Agent: - Vetoquinol - *25% Squalene* - No hearing loss, inflammation when injected into middle ear

Cerumene - Treatment of choice when doing a flush - Can be sent home with client

Ceruminolytic Agent: - Dechra - *22% Squalene*

KlearOtic

Treatment of Otitis: - Applied after cleaning with ceruminolytic agent - Prophylactic treatment of *swimmer's ear* - Maintenance ear program to keep infections from recurring or just normal maintenance

Cleaning and Drying Agents

List the Ear cleaning/drying agents:

- Douxo micellar Solution, Ceva - EpiOtic Advanced, Virbac - Malacetic Otic, Dchra - Vet solutions Ear Cleaning Solution - Gent-L-Clens, Merck - Oti-Clens, Zoetis - OtoCetic solution, Vedco

Treatment of Otitis: Usually contain combinations of antibiotics, antifungals, +/- glucocorticoids

Topical

Topical therapy: - *Antipruritic, anti-inflammatory, antiproliferative* - Decrease sebaceous and apocrine secretions - Even topical glucocorticoids (dexamethasone, triamcinolone) may cause adrenal suppression

Glucocorticoids

Topical Glucocorticoids: - Vedco - Burow's solution, *1% hydrocortisone* - Dries the ear

Cort/Astrin

Topical Glucocorticoids: - Zoetis - *0.01% fluocinolone acetonide*, DMSO (helps w/ absorbption) - low percentage

Synotic

Topical Antibiotics: - Good activity against most otic pathogens - Gram positive - Gram negative (not efficaceous against chronic *P. aeruginosa*) - Ototoxicity is a concern in humans - Inactivated in purulent debris

Aminoglycosides - *Neomycin sulfate* - Combination - Solution - Tresaderm - Merial - Thiabendazole, dexamethasone

Aminoglycosides: - Neomycine sulfate - Gentamicin sulfate

1st Line

Aminoglycoside: - Combination - Solution - *Tresaderm* - Merial - Thiabendazole, dexamethasone

*Neomycin sulfate*

Aminoglycoside: - Combination - Ointment - *Panolog* - Zoetis - Nystatin, thiostrepton, triamcinolone acetonide

*Neomycin sulfate* - Quadruple

Aminoglycoside: - Combination - Ointment - *Otomax* - Merck - Clotrimazole, Betamethasone valerate

*Gentamicin sulfate*

Aminoglycoside: - Combination - Suspension - *Mometamax* - Merck - Once daily application - Clotrimazole, mometasone furoate

*Gentamicin sulfate*

Aminoglycoside: - Combination - Suspension - *easOtic* - Virbac Animal Health - Once daily application - Micanazole, Hydrocortisone aceponate (HCA) (soft steroid)

*Gentamicin sulfate*

Topical Antibiotic: - Good activity against gram-positive and gram-negative organisms - Esp useful for Pseudomonas aeruginosa - Also E. coli, enterobacter, Klebsiella - NOT EFFECTIVE against Proteus - Inactivated in purulent debris - Synergistic effects when combined with miconazole against gram-negative (E. coli, PA) and Malassezia pachydermatis

Polymyxin B

List 2nd line of Topical Antibiotics:

- Polymyxin B

Topical Antibiotics: - Combination - Suspension - *Surolan* - Elanco - Miconazole, prednisolone

Polymyxin B

Topical Antibiotic: - Good activity against Staphylococcus pseudintermedius and E. coli - NOT EFFECTIVE against Pseudomonas aeruginosa

Florfenicol (1st line)

Topical Antibiotics: - Combination - Otic gel - *Osurnia* - Elanco - Terbinafine, betamethasone acetate - 2 doses - 45 days - NOT an ear pack

Florfenicol

Topical Antibiotic: - Combination - Otic Solution - Bayer - Terbinafine, mometasone furoate - 1 dose - 30 days - NOT an ear pack - Not refrigerated

*Florfenicol* - Claro

Topical Antibiotics: - Bactericidal - Gram-positive and gram-negative aerobes - Staphylococcus pseudintermedius - E. coli, Proteus spp,. Enterobacter spp., Klebsiella spp. - Pseudomonas aeruginosa - Little or no efficacy: - Streptococcus spp., enterococcus spp. - Anaerobes - *Reserve* infections resistant to other antimicrobial agents and susceptible Pseudomonas aeruginosa

Fluroquinolones

Topical Antibiotics: 2nd Line - Fluroquinolone - *Enrofloxacin* - Combination - Emulsion - Bayer Animal Health - *Silver sulfadiazine*

Baytril Otic - lacking GC (can always be added on)

Topical Antibiotics: 2nd Line - Fluroquinolone - *Orbifloxacin* - Combination - Suspension - Merck - Once daily application - Posaconazole, mometasone

Posatex

Topical Antibiotics: 2nd Line - *Fluoroquinolone* - Enrofloxacin - Extra-label - Bayer Animal Health - 1:4 with vehicle - CortAstrin, Synotic - Saline - 1:1:1 with - 2mg/mL inject dexamethasone - 1% miconazole

Baytril - we don't know stability - after one month, need to be discarded

- Cell surface of *gram-negative* bacteria are damaged by exposure of cells to EDTA - Leakage of cellular compinents, permeability of antibiotics - Tromethamine enhances the effect of EDTA

Tris-EDTA

Topical Antibacterial: - Chlorhexidine

Antiseptics

(T/F) If you want to use a Chlorhexidine product in the ears use Nolvasan Otic

False

Topical Antibacterial: - Malaseb Flush, Bayer Animal Health - Chlorhexidine - Miconazole (ant-yeast)

Chlorhexidine

Topical Therapy: - Thiabendazole - Clotrimazole - Nystatin - *Terbinafine* - Ketoconazole - Miconazole

Antifungals

- Lanolin-based otic -- Oily, waxy substance - Compounded - Liquid at room temp, thick goopy oil in ear - Applied in-office -- last for 10-14 days -- convenience for owner - ISSUES: - Conductive hearing loss - NO Solvent to remove - can't be removed, will go away on its own - Ototoxic - What to use instead for cocci/yeast? - *Claro or Osurnia*

Otic "Packs"

Topical Parasiticidals: The following are going to be used for ... - Thiabendazole (Tresaderm) - Ivermectin (Acarexx) - Milbemycin (Milbemite)

Ear mites

Definition: Semipermeable barrier that serves as a physiological barrier from external agents including bacteria, fungi, and chemicals while preventing the loss of fluids and solutes from the internal environment

stratum corneum

Otic Treatments: Part 2

Systemic Antibiotics: Cephalosporins (cocci) - *Cephalexin* - Generics - Rilexine, Virbac - *Cefadroxil*: Cefa-drops

First generation - we prefer this generation

Systemic Antibiotics: Cephalosporins (cocci) - *Cefpodoxime*: Simplecef, Zoetis generics

Third generation

Systemic Antibiotics: - Amoxicillin trihydrate-clavulanate potassium - Zoetis - 14 to 22 mg/kg q12h

Clavamox - expensive option - Cocci

Systemic Antibiotics: Fluoroquinolones (Rods) List them:

- Baytril (enrofloxacin) - 5 to *20 mg/kg* q24h - Zeniquin (marbofloxacin) - 2.75 to *5.5 mg/kg* q24h - Ciprofloxacin - *Inconsistent absorption* -- Canine - may not work

List the Systemic Antifungals:

- Ketoconazole - Nizoral, Janssen; generics - Itraconazole - It is rare to fing yeast otitis media in a cat, but if found *use this*

List Systemic Antiparasiticide:

- Ivermectin - ear mites - Extra - label usage - **Caution** - Selamectin - Revolution, Revolution Plas (cats) - Imidacloprid + moxidectin - Advantage Multi - Labeled for cats: ear mites - Bayer Animal Health - Isoxazoline - Off-label for ear mites - Simparica (Sarolaner [dogs]) - Nexgard - Bravecto

List Systemic Glucocorticoids:

- Prednisone - Stenosis, edema, hyperplasia - otic exam, cleaning - decrease to alternate dose

When is maintenance ear therapy useful?

- Chronic recurrent otitis externa - Probably lost the ability to self clean - Previous *Pseudomonas* otitis infection - While diagnosing primary disease

What does an "Maintenance ear Therapy" include?

- Ear cleaning and drying agent - TrisEDTA - +/- Glucocorticoid (mostly used when still trying (diagnose primary disease)

How long do we moitor?

- Every 2 to 4 weeks - Otoscopic/video otoscopic exam - Cytology

What is the surgery of choice?

Total ear canal ablation/bulla osteotomy (TECABO)