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Dermatology > Otitis Externa > Flashcards

Otitis Externa Flashcards

1
Q

What 5 openings will you find in the tympanic bulla?

A
  1. Cochlear (round) window
  2. Vestibular (oval) window
  3. Bulla septum
  4. Eustachian tube
  5. Promontory
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2
Q

What makes up the inner ear?

A
  • Bony labyrinth
    • cochlea
    • semicircular canals
    • vestible
  • Membranous labyrinth
    • utricle
    • saccule
    • ampulla
    • crista
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3
Q

Describe the tympanic membrane

A
  • 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
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4
Q

Define otitis

A
  • 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
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5
Q

What are the predisposing factors for otitis externa?

A
  • 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
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6
Q

Describe Otodectes cynotis

A
  • 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
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7
Q

Describe Otobius megnini

A
  • 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
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8
Q

Describe Eutrombicula alfreddugesi

A
  • 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
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9
Q

Describe Otodemodicosis

A
  • 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!
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10
Q

Describe Sarcoptes scabiei var. canis

A
  • aka “canine scabies”
  • usually ear tips
    • can be OE also
  • severe pruritus
  • female burrows in epidermis and lays eggss
  • thick, yellow crusts
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11
Q

Describe Notoedres cati

A
  • aka “feline scabies”
  • medial proximal pinnae
  • face, eyelids, neck, feet, perineum
  • female mites burrow
  • intense pruritus
  • highly contagious
  • easy to find
    • abundant mites
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12
Q

What is the etiology for foreign body- induced otitis externa? Describe the clinical signs and treatment for this.

A
  • Etiology:
    • plant awns (barley)
    • insect
    • sand
    • dry medications
  • C/S:
    • acute/chronic unilateral otitis
  • Tx:
    • remove the FB
    • topical abx
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13
Q

Describe intraluminal tumors

A
  • relatively uncommon
    • dogs
  • obstructive lesions
  • ulceration and necrosis
  • malignant: cats>dogs
    • ceruminous gland adenocarcinoma
    • SCC
    • mast cell tumors
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14
Q

Describe nasopharyngeal polyps

A
  • Etiology:
    • congenital
    • bacterial
    • calicivirus
  • C/S:
    • chronic uni/bilateral otitis
    • mass in ear canal
    • head tilt
  • Tx:
    • surgery
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15
Q

Describe apocrine cystomatosis

A
  • 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
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16
Q

Describe the etiology of allergen-induced otitis externa. What are the clinical signs and treatment for this?

A
  • Etiology:
    • food allergy
    • atopic dermatitis
    • contact allergy
      • drug reactions
  • C/S:
    • chronic bilateral otitis
    • dermatitis
  • Tx:
    • tx the allergy
    • tx the infection
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17
Q

Describe atopic dermatitis as a factor for otitis externa

A
  • Erythema and inflammation
    • pinnae
    • vertical canal
      • initial clinical sign
    • entire ear canal
      • more chronic
    • 50% of atopic dogs have bilateral OE
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18
Q

What is the percentage of food allergy cases that have OE?

A

80%

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19
Q

Is contact allergy a common etiological factor for OE? How is it treated?

A
  • no, it is not common
  • Topical tx:
    • neomycin/gentamycin
    • miconazole 1%
    • propylene glycol
      • in many products
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20
Q

What are some examples of disorders of keritinization that result in OE?

A
  • primary idiopathic seborrhea
  • hypothyroidism
  • sex hormone imbalance
  • lipid related conditions
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21
Q

Describe primary idiopathic seborrhea

A
  • incr cerumen production
  • altered cerumen composition
  • delayed desquamation and stenosis
  • often progresses to calcifying OE and OM in the Cocker spaniel
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22
Q

Describe the etiology, pathogenesis, clinical signs, and treatment for endocrinopathy-induced OE

A
  • 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
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23
Q

What are three autoimmune diseases that can cause OE?

A
  • Pemphigus foliaceus
  • Pemphigus erythematosus
  • Systemic lupus erythematosus
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24
Q

Describe juvenile cellulitis

A
  • 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
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25
Q

What are some secondary factors that can cause OE?

A
  • infection secondary to the inflammatory process
    • bacteria
    • yeasts
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26
Q

What are some bacteria can cause OE?

A
  • S. pseuintermedius (30-50% of cases)
  • Proteus mirabilis
  • Pseudomonas spp.
  • Escherichia coli
  • Klebsiella spp.
  • Corynebacterium spp.
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27
Q

What are some yeast species that may cause OE?

A
  • Malassezia pachydermatis (found in normal canine/feline ears)
  • Candida albicans
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28
Q

What are some pathologic changes that are perpetuating factors of OE?

A
  • Epidermal
    • hyperkeratosis
    • hyperplasia
    • epithelial folds
  • Dermal
    • edema and fibrosis
  • Adnexal
    • ceruminal gland hyperplasia or hypertrophy
  • Lumen stenosis
  • Calcification
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29
Q

What changes to the tympanic membrane are perpetuating factors of OE?

A
  • opacity
  • dilation
  • diverticulum
30
Q

What are some perputating factors of OE that can be caused by otitis media?

A
  • epithelial changes
  • purulent accumulation
  • caseation
  • cholesteatoma
    • skin growth in middle ear
  • proliferation
  • destructive osteomyelitis
31
Q

What are the aspects of a patient’s history you want to know to help guide your diagnosis for OE?

A
  • age of onset
  • breed
  • duration
  • seasonality
  • unilateral vs. bilateral
  • prev meds
  • environ factors
32
Q

What are the clinical signs of OE?

A
  • odor
  • head shaking
  • d/c
  • pruritus
  • aural hematoma
  • head tilt
  • pain
  • erythema
  • edema
  • lichenification
  • hyperpigmentation
  • exoriations
  • mineralizations
33
Q

What are some causes of otitis media?

A
  • extension of otitis externa
    • most common
  • ascending infection via eustachian tube
  • hematogenous spread
34
Q

Why can diagnosis of OM be difficult?

A
  • ear canal filled w/ debris/exudate
  • stenotic
  • painful and difficult to examine
  • inability to visualize the TM
35
Q

What are the clinical signs of OM?

A
  • 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
36
Q

How do you diagnose OM?

A
  • 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
37
Q

Why perform a deep ear flush when you’re performing a video-otoscopy?

A
  • 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
38
Q

True or False: the external and middle ear often have different microorganisms

A

true; why you should perform cytologies of both

39
Q

What are the added benefits of using a video-otoscope while performing deep ear flushes?

A
  • significant decr in time of procedure
40
Q

Describe myringotomies

A
  • 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
41
Q

After a deep ear flush, what should you do therapeutically?

A
  • instill antibiotic
  • steroids:
    • decr inflamm and stenosis
    • incr comfort and owners ability to tx
    • oral pred or triamcinolone
    • topical dexamethasone
42
Q

What should your therapeutic plan be following a myringotomy?

A
  • 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
43
Q

What are potential complications of treating OE or myringotomies?

A
  • iatrogenic rupture of TM
    • not healthy TM
  • pain
  • Horner’s syndrome
  • facial paralysis
  • KCS (nerve damage)
  • vestibular signs
  • deafness
44
Q

What are the pros and cons of an ear biopsy?

A
  • Pros:
    • ID the mass
      • inflamm vs. neoplasia
    • best tx choice and prognosis
  • Cons:
    • small samples
    • low sensitivity and specificity
45
Q

What are imaging studies useful for diagnosing with otitis issues?

A
  • neoplasia
  • otitis media
  • calcification of ear canal
46
Q

What are the pros and cons for using radiographs for OM/OE diagnoses?

A
  • Pros
    • availability
    • cheaper
  • Cons
    • non sensitive
    • non specific
    • time-consuming
    • bad quality
    • anesthesia
47
Q

What are the pros and cons for using CT scans for OM/OE diagnoses?

A
  • Pros
    • better definition
    • very sensitive
    • very specific
    • quick test
  • Cons
    • expensive
    • anesthesia (+/-)
48
Q

What are the pros and cons for using MRI for OM/OE diagnoses?

A
  • Pros
    • better for soft tissue
  • Cons
    • expensive
    • not ideal for bone involvement
    • anesthesia
49
Q

When are cultures and sensitivities useful when diagnosing otic diseases?

A
  • otitis media
  • systemic abx for otitis media or externa
    • intracellular accumulation
50
Q

What are the pros and cons for using cultures for OM/OE diagnoses?

A
  • 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
51
Q

What are your treatment options otitis externa?

A
  • Medical
    • topicals:
      • cleansers
      • antimicrobials
    • systemic drugs:
      • antimicrobials
      • anti-inflamms
  • Surgical
    • TECA-BO
    • vertical canal ablation and lateral wall resection
52
Q

What are your treatment options otitis media?

A
  • Medical
    • Topicals
    • Systemic drugs
  • Surgical
    • TECA-BO
    • VBO
53
Q

What are your principles of treatment for OE/OM?

A
  • treat the primary cause!
  • treat the perpetuating factors!
  • use topical meds
  • use weekly flushing
  • systemic antimicrobials are NOT useful alone
  • systemic glucocorticoids ARE useful
54
Q

What are some ear cleansers you can use?

A
  • Inhibit microbes:
    • Tris-EDTA
    • Chlorhexidine
    • Ketoconazole
    • Acetic acid
  • Ceruminolytic:
    • Squalene
    • Propylene glycol

*use cotton balls for application, use weekly/biweekly

55
Q

Describe cerumynolytics

A
  • 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
56
Q

Describe acidifying agents

A
  • 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
57
Q

What are some potential astringents/anesthetics/antimicrobial agents you can use for OE/OM therapy?

A
  • Astringents:
    • Burrow’s, domoboro, isopropyl alcohol
  • Anesthetic
    • Proparacaine, lidocaine, pramoxine
  • Antimicrobial
    • Chlorhexidine
    • Ketoconazole
    • Hypochlorous acid
58
Q

What is Tris-EDTA?

A
  • Alkalizing agent
    • works well with AG and fluoroquinolones
  • Chelating agent
    • disrupts cell membrane of bacteria and enhances abx tx
59
Q

What are some antibiotics typically used for OE/OM treatment?

A
  • Aminoglycosides (AG)
    • inactivated by low pH or debris
      • Neomycin (Tresaderm)
      • Gentamycin (Otomax, Mometamax, Easotic)
      • Tobramycin (Tobradex)
      • Amikacin
  • Fluoroquinolones
    • Enrofloxacin 0.9%
      • ALWAYS assoc w/ a topical antifungal!
    • Orbifloxacin
  • Cationic peptides
    • Polymixin B
    • Florfenicol
60
Q

What are some alternatives to systemic antibiotics?

A
  • Ophthalmic meds
    • 0.3% tobramycin (Tobrex)
    • Chloramphenicol
    • Polymixin B (Polytrim)
61
Q

List some antifungals to be used for OE/OM treatment

A
  • Miconazole (Conofite)
  • Clotrimazole (Otomax)
  • Nystatin (Panalog)
  • Thiabendazole (Tresaderm)
  • Posaconazole (Posatex)
  • Terbinafine (Osurnia)
62
Q

What are some topical glucocorticoids used in OE/OM treatment?

A
  • Syn-otic
  • Betamethasone
  • Dexamethasone
  • Mometasone
  • Hydrocortisone aceponate/Hydrocortisone
  • Prenisolone

*topical formulations are less effective

63
Q

What makes anti-inflammatory agents useful for treating OE/OM?

A
  • useful to decr pruritus/pain and inflammation
  • decr stenosis d/t fibrotic changes
    • NO mineralization
64
Q

In what cases should you use systemic antibiotics?

A
  • only in cases of otitis media
  • extremely severe and chroinc otitis externa
    • fluoroquinolones
    • clindamycin
  • always WITH topical tx
65
Q

What are two systemic glucocorticoids used in OE/OM treatment?

A
  • Prednisone/-lone
  • Methylprednisolone
66
Q

Antimicrobial treatment for OM should last at least how long?

A

6-8 weeks of both topical and systemic abx; systemic tx will be based on C&S

67
Q

What antibiotics are effective for OM caused by Methicillin resistant Staph species?

A
  • 99% = S. pseudintermedius
    • Cephalexin
    • Simplicef
    • Clavamox
    • Clindamycin
68
Q

What should your therapy regimen be for OM due to rod-shaped bacteria?

A
  • 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
69
Q

What is your therapy for OM caused by Malassezia spp?

A
  • Systemic tx
    • Ketoconazole
      • w/ food and avoid in cats
    • Itraconazole
      • Solution: Empty stomach
      • Capsules: with food
    • Fluconazole
70
Q

How should you follow up for OM?

A
  • 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

Dermatology (13 decks)

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