Otitis Externa Flashcards
What 5 openings will you find in the tympanic bulla?
- Cochlear (round) window
- Vestibular (oval) window
- Bulla septum
- Eustachian tube
- Promontory
What makes up the inner ear?
- Bony labyrinth
- cochlea
- semicircular canals
- vestible
- Membranous labyrinth
- utricle
- saccule
- ampulla
- crista
Describe the tympanic membrane
- pars flaccida - smaller upper part
- pink, loosely attached region forming dorsal quadrant containing small b.v.
- pars tensa - firmly attached
- thin, tough, pearl-gray structure with radiating strands
Define otitis
- inflammation of the ear
- externa = ear canal
- media = bulla
- interna = canaliculi and/or cochlea
- it is a clinical sign and NOT a disease
- otitis externa is one of the most common disorders in medicine
What are the predisposing factors for otitis externa?
-
Conformation:
- pendulous ears
- excessive hair
- on pinna (Cockers)
- in canal (Poodles, terriers)
- stenotic ears
- breed related
-
Excessive moisture and humidity
- swimmer’s ear
- humid climate
- Excessive cerumen production
-
Inappropriate treatment
- trauma from applicators
- topical irritants (propylene glycol)
- over treatment
- hair plucking, over cleaning
-
Obstructive ear dz (can be primary too)
- neoplasia
- polyps
- FB
-
Systemic dz
- catabolic states
- immune suppression (FIV, FeLV, neoplasia)
- debilitation
Describe Otodectes cynotis
- aka “ear mite”
- non-burrowing psoroptid mite
- obligatory parasite
- 50% of OE in cats, 5-10% in dogs
- survive on skin surface
- protected by thick, brown crust
- feed on lymph and blood
- more common in animals < 1 yr of age
Describe Otobius megnini
- aka “spinous ear tick”
- SW US
-
larvae and nymphs induce inflammation
- larvae live in ear canal 7 mo before molting to nymphs
- drops to ground as an adult
- also reported in horses, cows, llamas
Describe Eutrombicula alfreddugesi
- aka “chiggers”
- bite causes irritation and variable pruritus
- legs, feet, head, ventrum
- size of a head of a pin
- seasonal - late summer/fall
- contact w/ woods and fields
- orange-red in color
Describe Otodemodicosis
- more common in cats (D. cati)
- Ceruminous otitis externa
- Suspect immunosuppressive dz
- FeLV, FIV, diabetes, neoplasia
- Evident on an ear swab
- do not need to scrape the ear!
Describe Sarcoptes scabiei var. canis
- aka “canine scabies”
- usually ear tips
- can be OE also
- severe pruritus
- female burrows in epidermis and lays eggss
- thick, yellow crusts
Describe Notoedres cati
- aka “feline scabies”
- medial proximal pinnae
- face, eyelids, neck, feet, perineum
- female mites burrow
- intense pruritus
- highly contagious
- easy to find
- abundant mites
What is the etiology for foreign body- induced otitis externa? Describe the clinical signs and treatment for this.
- Etiology:
- plant awns (barley)
- insect
- sand
- dry medications
- C/S:
- acute/chronic unilateral otitis
- Tx:
- remove the FB
- topical abx
Describe intraluminal tumors
- relatively uncommon
- dogs
- obstructive lesions
- ulceration and necrosis
- malignant: cats>dogs
- ceruminous gland adenocarcinoma
- SCC
- mast cell tumors
Describe nasopharyngeal polyps
- Etiology:
- congenital
- bacterial
- calicivirus
- C/S:
- chronic uni/bilateral otitis
- mass in ear canal
- head tilt
- Tx:
- surgery
Describe apocrine cystomatosis
- cysts of apocrine glands
- C/S:
- adult animals
- solitary, well-circumscribed, smooth, bluish tense swelling
- concave surface of pinna
- vertical ear canal
- uni/bilaterally
- Tx:
- benign neglect
- surgery
Describe the etiology of allergen-induced otitis externa. What are the clinical signs and treatment for this?
- Etiology:
- food allergy
- atopic dermatitis
- contact allergy
- drug reactions
- C/S:
- chronic bilateral otitis
- dermatitis
- Tx:
- tx the allergy
- tx the infection
Describe atopic dermatitis as a factor for otitis externa
- Erythema and inflammation
- pinnae
- vertical canal
- initial clinical sign
- entire ear canal
- more chronic
- 50% of atopic dogs have bilateral OE
What is the percentage of food allergy cases that have OE?
80%
Is contact allergy a common etiological factor for OE? How is it treated?
- no, it is not common
- Topical tx:
- neomycin/gentamycin
- miconazole 1%
- propylene glycol
- in many products
What are some examples of disorders of keritinization that result in OE?
- primary idiopathic seborrhea
- hypothyroidism
- sex hormone imbalance
- lipid related conditions
Describe primary idiopathic seborrhea
- incr cerumen production
- altered cerumen composition
- delayed desquamation and stenosis
- often progresses to calcifying OE and OM in the Cocker spaniel
Describe the etiology, pathogenesis, clinical signs, and treatment for endocrinopathy-induced OE
- Etiology:
- hypothyroidism
- sex hormone imbalance
- Pathogenesis:
- incr mucin deposition in dermis
- hyperplasia/hyperkeratosis of epidermis
- altered fatty acids productions
- C/S:
- chronic bilateral otitis
- dermatitis
- Tx:
- hormone supplement
- surgery
What are three autoimmune diseases that can cause OE?
- Pemphigus foliaceus
- Pemphigus erythematosus
- Systemic lupus erythematosus
Describe juvenile cellulitis
- Puppies 3-16 wks old
- older dogs have been reported
- vesiculopustular dz
- unknown etiology
- Dachshunds, Golden Retrievers, Pointers
- Purulent otitis with head and facial lesions
- Blepharitis, lymphadenopathy
What are some secondary factors that can cause OE?
- infection secondary to the inflammatory process
- bacteria
- yeasts
What are some bacteria can cause OE?
- S. pseuintermedius (30-50% of cases)
- Proteus mirabilis
- Pseudomonas spp.
- Escherichia coli
- Klebsiella spp.
- Corynebacterium spp.
What are some yeast species that may cause OE?
- Malassezia pachydermatis (found in normal canine/feline ears)
- Candida albicans
What are some pathologic changes that are perpetuating factors of OE?
- Epidermal
- hyperkeratosis
- hyperplasia
- epithelial folds
- Dermal
- edema and fibrosis
- Adnexal
- ceruminal gland hyperplasia or hypertrophy
- Lumen stenosis
- Calcification
What changes to the tympanic membrane are perpetuating factors of OE?
- opacity
- dilation
- diverticulum
What are some perputating factors of OE that can be caused by otitis media?
- epithelial changes
- purulent accumulation
- caseation
- cholesteatoma
- skin growth in middle ear
- proliferation
- destructive osteomyelitis
What are the aspects of a patient’s history you want to know to help guide your diagnosis for OE?
- age of onset
- breed
- duration
- seasonality
- unilateral vs. bilateral
- prev meds
- environ factors
What are the clinical signs of OE?
- odor
- head shaking
- d/c
- pruritus
- aural hematoma
- head tilt
- pain
- erythema
- edema
- lichenification
- hyperpigmentation
- exoriations
- mineralizations
What are some causes of otitis media?
- extension of otitis externa
- most common
- ascending infection via eustachian tube
- hematogenous spread
Why can diagnosis of OM be difficult?
- ear canal filled w/ debris/exudate
- stenotic
- painful and difficult to examine
- inability to visualize the TM
What are the clinical signs of OM?
- Neuro signs:
- facial n. paralysis
- KCS
- Horner’s syndrome: mioisis, enophthalmos, ptosis, protrusion of 3rd eyelid
- Periph vestibular dz
- head tilt, nystagmus
- same side as otitis
- ataxia and loss of balance
- alert and have normal mentation
- +/- nausea and vomiting
How do you diagnose OM?
- ear cytology - extremely informative
- video-otoscopy - under GA w/ trach tube, used to visualize TM
- deep ear flushing and myringotomy
- diagnostic imaging
- xray vs. CT vs. MRI
- biopsy
- culture and sensitivity
Why perform a deep ear flush when you’re performing a video-otoscopy?
- removes exudate
- allows visualization of the TM
- un-mask a FB or tumor
- purulent d/c will inactivate meds (Gentamicin, polymixin B)
- perform myringotomy
- collect a culture/cytology of middle ear
- flush out middle ear
True or False: the external and middle ear often have different microorganisms
true; why you should perform cytologies of both
What are the added benefits of using a video-otoscope while performing deep ear flushes?
- significant decr in time of procedure
Describe myringotomies
- surgical rupture of TM
- diagnostic
- collection of material: culture and PCR
- take cultures before and after procedure (sterile vs. non-sterile swabs)
- therapeutic: flushing of the bulla, permanent opening
After a deep ear flush, what should you do therapeutically?
- instill antibiotic
- steroids:
- decr inflamm and stenosis
- incr comfort and owners ability to tx
- oral pred or triamcinolone
- topical dexamethasone
What should your therapeutic plan be following a myringotomy?
- send patient home with topical flush, topical med, and oral abx based on best guess
- change tx (if needed) once you receive your C&S results
What are potential complications of treating OE or myringotomies?
- iatrogenic rupture of TM
- not healthy TM
- pain
- Horner’s syndrome
- facial paralysis
- KCS (nerve damage)
- vestibular signs
- deafness
What are the pros and cons of an ear biopsy?
- Pros:
- ID the mass
- inflamm vs. neoplasia
- best tx choice and prognosis
- ID the mass
- Cons:
- small samples
- low sensitivity and specificity
What are imaging studies useful for diagnosing with otitis issues?
- neoplasia
- otitis media
- calcification of ear canal
What are the pros and cons for using radiographs for OM/OE diagnoses?
- Pros
- availability
- cheaper
- Cons
- non sensitive
- non specific
- time-consuming
- bad quality
- anesthesia
What are the pros and cons for using CT scans for OM/OE diagnoses?
- Pros
- better definition
- very sensitive
- very specific
- quick test
- Cons
- expensive
- anesthesia (+/-)
What are the pros and cons for using MRI for OM/OE diagnoses?
- Pros
- better for soft tissue
- Cons
- expensive
- not ideal for bone involvement
- anesthesia
When are cultures and sensitivities useful when diagnosing otic diseases?
- otitis media
- systemic abx for otitis media or externa
- intracellular accumulation
What are the pros and cons for using cultures for OM/OE diagnoses?
- Pros
- bacterial ID
- sensitivity for systemic abx
- Cons
- sensitivity based on blood concentration
- underestimation of useful antimicrobials
- low blood flow in ears
- clinical relevance in otitis
- pH and aminoglycosides
- lack of correlation w/ clinical response
- sensitivity based on blood concentration
What are your treatment options otitis externa?
- Medical
- topicals:
- cleansers
- antimicrobials
- systemic drugs:
- antimicrobials
- anti-inflamms
- topicals:
- Surgical
- TECA-BO
- vertical canal ablation and lateral wall resection
What are your treatment options otitis media?
- Medical
- Topicals
- Systemic drugs
- Surgical
- TECA-BO
- VBO
What are your principles of treatment for OE/OM?
- treat the primary cause!
- treat the perpetuating factors!
- use topical meds
- use weekly flushing
- systemic antimicrobials are NOT useful alone
- systemic glucocorticoids ARE useful
What are some ear cleansers you can use?
- Inhibit microbes:
- Tris-EDTA
- Chlorhexidine
- Ketoconazole
- Acetic acid
- Ceruminolytic:
- Squalene
- Propylene glycol
*use cotton balls for application, use weekly/biweekly
Describe cerumynolytics
- for ceruminous ears
- used to soften impacted material prior to deep flushing
- some are irritating and potentially ototoxic
- e.g. propylene glycol, lanolin, glycerine, squalene, urea peroxide, DSS, mineral oil
Describe acidifying agents
- dry the ear canal
- less habitable for microbes
- not used with AG
- e.g. Acetic acid, lactic acid, malci acid, boric acid, benzoic acid, salicyclic acid
What are some potential astringents/anesthetics/antimicrobial agents you can use for OE/OM therapy?
- Astringents:
- Burrow’s, domoboro, isopropyl alcohol
- Anesthetic
- Proparacaine, lidocaine, pramoxine
- Antimicrobial
- Chlorhexidine
- Ketoconazole
- Hypochlorous acid
What is Tris-EDTA?
- Alkalizing agent
- works well with AG and fluoroquinolones
- Chelating agent
- disrupts cell membrane of bacteria and enhances abx tx
What are some antibiotics typically used for OE/OM treatment?
- Aminoglycosides (AG)
- inactivated by low pH or debris
- Neomycin (Tresaderm)
- Gentamycin (Otomax, Mometamax, Easotic)
- Tobramycin (Tobradex)
- Amikacin
- inactivated by low pH or debris
- Fluoroquinolones
- Enrofloxacin 0.9%
- ALWAYS assoc w/ a topical antifungal!
- Orbifloxacin
- Enrofloxacin 0.9%
- Cationic peptides
- Polymixin B
- Florfenicol
What are some alternatives to systemic antibiotics?
- Ophthalmic meds
- 0.3% tobramycin (Tobrex)
- Chloramphenicol
- Polymixin B (Polytrim)
List some antifungals to be used for OE/OM treatment
- Miconazole (Conofite)
- Clotrimazole (Otomax)
- Nystatin (Panalog)
- Thiabendazole (Tresaderm)
- Posaconazole (Posatex)
- Terbinafine (Osurnia)
What are some topical glucocorticoids used in OE/OM treatment?
- Syn-otic
- Betamethasone
- Dexamethasone
- Mometasone
- Hydrocortisone aceponate/Hydrocortisone
- Prenisolone
*topical formulations are less effective
What makes anti-inflammatory agents useful for treating OE/OM?
- useful to decr pruritus/pain and inflammation
- decr stenosis d/t fibrotic changes
- NO mineralization
In what cases should you use systemic antibiotics?
- only in cases of otitis media
- extremely severe and chroinc otitis externa
- fluoroquinolones
- clindamycin
- always WITH topical tx
What are two systemic glucocorticoids used in OE/OM treatment?
- Prednisone/-lone
- Methylprednisolone
Antimicrobial treatment for OM should last at least how long?
6-8 weeks of both topical and systemic abx; systemic tx will be based on C&S
What antibiotics are effective for OM caused by Methicillin resistant Staph species?
- 99% = S. pseudintermedius
- Cephalexin
- Simplicef
- Clavamox
- Clindamycin
What should your therapy regimen be for OM due to rod-shaped bacteria?
- Species:
- Pseudomonas spp.
- Corynebacterium spp.
- E. coli
- P. mirabilis
- Systemic tx
- Enrofloxacin, Ciprofloxacin, Marbofloxacin
- choice should be based on C&S
- may be useful to pick an oral and a topical abx with diff MOAs against the bacteria
What is your therapy for OM caused by Malassezia spp?
- Systemic tx
- Ketoconazole
- w/ food and avoid in cats
- Itraconazole
- Solution: Empty stomach
- Capsules: with food
- Fluconazole
- Ketoconazole
How should you follow up for OM?
- Follow up care: recheck q 2 wks
- Dogs comfort should be constantly improving
- use of steroids helps
- complications:
- resistant organism
- new organism
- contact hypersensitivity
- Neomycin
- PPG
- owner non-compliance
