Dermatology > Otitis Externa > Flashcards

Otitis Externa Flashcards

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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
What are some secondary factors that can cause OE?
* infection secondary to the inflammatory process * bacteria * yeasts
26
What are some bacteria can cause OE?
* S. pseuintermedius (30-50% of cases) * Proteus mirabilis * Pseudomonas spp. * Escherichia coli * Klebsiella spp. * Corynebacterium spp.
27
What are some yeast species that may cause OE?
* Malassezia pachydermatis (found in normal canine/feline ears) * Candida albicans
28
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
29
What changes to the tympanic membrane are perpetuating factors of OE?
* opacity * dilation * diverticulum
30
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
31
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
32
What are the clinical signs of OE?
* odor * head shaking * d/c * pruritus * aural hematoma * head tilt * pain * erythema * edema * lichenification * hyperpigmentation * exoriations * mineralizations
33
What are some causes of otitis media?
* extension of otitis externa * **most common** * ascending infection via eustachian tube * hematogenous spread
34
Why can diagnosis of OM be difficult?
* ear canal filled w/ debris/exudate * stenotic * painful and difficult to examine * inability to visualize the TM
35
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
36
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
37
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
38
True or False: the external and middle ear often have different microorganisms
true; why you should perform cytologies of both
39
What are the added benefits of using a video-otoscope while performing deep ear flushes?
* **significant decr in time of procedure**
40
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
41
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
42
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
43
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
44
What are the pros and cons of an ear biopsy?
* Pros: * ID the mass * inflamm vs. neoplasia * best tx choice and prognosis * Cons: * small samples * low sensitivity and specificity
45
What are imaging studies useful for diagnosing with otitis issues?
* neoplasia * otitis media * calcification of ear canal
46
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
47
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 (+/-)
48
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
49
When are cultures and sensitivities useful when diagnosing otic diseases?
* otitis media * systemic abx for otitis media or externa * intracellular accumulation
50
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_
51
What are your treatment options otitis externa?
* Medical * topicals: * cleansers * antimicrobials * systemic drugs: * antimicrobials * anti-inflamms * Surgical * TECA-BO * vertical canal ablation and lateral wall resection
52
What are your treatment options otitis media?
* Medical * Topicals * Systemic drugs * Surgical * TECA-BO * VBO
53
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
54
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_
55
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
56
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
57
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
58
What is Tris-EDTA?
* Alkalizing agent * works well with AG and fluoroquinolones * Chelating agent * disrupts cell membrane of bacteria and enhances abx tx
59
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 * Fluoroquinolones * Enrofloxacin 0.9% * ALWAYS assoc w/ a topical antifungal! * Orbifloxacin * Cationic peptides * Polymixin B * Florfenicol
60
What are some alternatives to systemic antibiotics?
* Ophthalmic meds * 0.3% tobramycin (Tobrex) * Chloramphenicol * Polymixin B (Polytrim)
61
List some antifungals to be used for OE/OM treatment
* Miconazole (Conofite) * Clotrimazole (Otomax) * Nystatin (Panalog) * Thiabendazole (Tresaderm) * Posaconazole (Posatex) * Terbinafine (Osurnia)
62
What are some topical glucocorticoids used in OE/OM treatment?
* Syn-otic * Betamethasone * Dexamethasone * Mometasone * Hydrocortisone aceponate/Hydrocortisone * Prenisolone * \*topical formulations are less effective
63
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
64
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**
65
What are two systemic glucocorticoids used in OE/OM treatment?
* Prednisone/-lone * Methylprednisolone
66
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
67
What antibiotics are effective for OM caused by Methicillin resistant Staph species?
* 99% = S. pseudintermedius * Cephalexin * Simplicef * Clavamox * Clindamycin
68
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
69
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
70
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
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