Canine Otitis Flashcards

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1
Q

What are the predisposing factors of canine otitis externa?

A
Conformation
Obstruction
Excessive moisture/cerumen/hair
Cornification disorders
Immunosuppression
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2
Q

What are the primary factors of canine otitis externa?

A

Foreign bodies
Parasites
Hypersensitivity skin disease such as atopic dermatitis or cutaneous food hypersensitivity
Contact dermatitis to topical ear products
Immune mediated disease
Miscellaneous

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3
Q

What are the secondary factors of canine otitis externa?

A

Bacteria - S. pseudintermedius, Pseudomonas, Proteus, Klebsiella, E. coli
Yeasts - Malassezia

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4
Q

What are the perpetuating factors of otitis externa?

A

Ear canal pathology including epidermal, dermal or adnexal changes
Stenosis of lumen

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5
Q

What do the perpetuating factors of canine otitis externa lead to?

A

Middle ear disease as the tympanic membrane is broken down

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6
Q

How does treatment for otitis media differ from otitis externa?

A

Need to switch to systemic treatment

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7
Q

What are the management aims of otitis externa?

A

Reverse the perpetuating factors
Resolve secondary infection
Address primary factors
Remove predisposing factors if you can

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8
Q

What are the characteristics of recurrent/chronic pruritic otitis externa?

A

Allergic skin disease with secondary bacterial/yeast/mixed overgrowth
Bilateral but not always concurrently or equally severe and can affect pinnae, meatus, canal or all three

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9
Q

How is recurrent/chronic pruritis otitis externa treated?

A

Removal of discharge and resolution/prevention of microbial complication
Effective control of allergic inflammation often required

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10
Q

What are the characteristics of chronic progressive purulent otitis?

A

Long-standing unresolved microbial infection that is multifactorial with soft tissue changes and/or otitis media

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11
Q

What are the characteristics of otitis media?

A

Acute otitis externa in 16% of cases and chronic/recurrent otitis externa in 50-80% of cases and typmanum is often in intact
Signs relate to OE and rarely neuro signs seen

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12
Q

Which factors don’t rule out otitis media?

A

Tympanic membrane intact
Imaging normal
No neuro signs

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13
Q

How does acute OM progress to chronic OM?

A

Microbial shift from g+ve and Malassezia to g-ve especially Pseudomonas
Multiple partially effective/ineffective antimicrobial treatment attempts causing antimicrobial resistance

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14
Q

What are the key diagnostic points for ear infections?

A

Cytology is indispensable for selection for bacterial culture, interpretation of culture result and nature of inflammatory response
Discordant microbial involvements at different sites
Poor repeatability of ear swab cultures

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15
Q

What are the indications for surgical treatment of OE or OM?

A

Tumours or polyps
Irreversible stenosis
Aggressive medical treatment failed/not possible/not wanted

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16
Q

What is the medical approach to treatment of OE and OM?

A

Resolve current infection by assessing and reversing perpetuating factors and resolving infection
Prevent recurrence of infection through addressing primary factors and removing predisposing factors

17
Q

How are perpetuating factors reversed?

A

Reverse stenosis, clean and examin ears under GA, home cleaning

18
Q

How are ear infections resolved?

A

Topical and systemic antibiotics with topical being most important

19
Q

How are primary factors addressed to reduce recurrence of OE and OM?

A

Investigate/control/resolve underlying diseases that are typically allergic

20
Q

What are the first line topical antibiotic treatments for ears?

A

AUROTO (cocci, g-ve) thiabendazole/neomycin
CANAURAL (cocci, g-ve) nystatin/diethanolamine fusidate/framycetin/prednisolone
SUROLAN (Malassezia, cocci, E. coli, Pseudo) miconazole/polymixin B/prednisolone

21
Q

What are the second line topical antibiotic treatments for ears?

A

EASOTIC (g-ve, Malassezia) miconazole/gentamicin/hydrocortisone aceponate
OTOMAX (g-ve, malassezia) clotrimazole/gentamicin/betamethasone

22
Q

What are the reserved topical antibiotic treatments for ears?

A

AURIZON clotrimazole/marbofloxacin/dexamethosone

POSATEX posaconazole/orbifloxacin/mometasone

23
Q

What are the common causes of treatment failure of OE and OM?

A

Treatment not done for long enough
Inadequate ear cleaning
Failure to identify and treat OM and soft tissue changes
Failure to identify and control primary causes of otitis

24
Q

What are the nine golden rules of ear disease treatment?

A

Stenosis = treatment failure
Aural lavage always under GA
Sample most proximal site affected
Systemic antibiotics normally not required
Conventional bacterial sensitivity testing of little value for topical therapy
Avoid human reserve antibiotics
Monitor response with cytology
Do not stop antimicrobials before complete clinical and microbiological cure
Be slow to withdraw cleaning

25
Q

What are the potential systemic adverse effects of ear treatments?

A

Glucocorticoids

Basal cortisol, ACTH stim, T4 and Insulin can all be altered

26
Q

What are the potential adverse effects to the outer ear when treating ear disease?

A

Occlustion/maceration of canal and TM, Epidermal turnover and migration, glandular changes, micro-foreign body formation, atrophic effects
Allergic/irritant dermatitis due to prolonged exposure, penetration enhancers and topical sensitisers

27
Q

What are the potential adverse effects to the middle ear when treating ear disease?

A

Facial nerve damage
Sympathetic neurons for ocular innervation damaged causing Horner’s syndrome
Otitis media, cholesteatoma

28
Q

What are the potential adverse effects to the inner ear when treating ear disease?

A

Ototoxicity due to drugs or chemicals that damage the inner ear or the vestibulo-cochlear nerve
May occur weeks later
Incidence unknown and seems rare