Canine Otitis Flashcards
What are the predisposing factors of canine otitis externa?
Conformation Obstruction Excessive moisture/cerumen/hair Cornification disorders Immunosuppression
What are the primary factors of canine otitis externa?
Foreign bodies
Parasites
Hypersensitivity skin disease such as atopic dermatitis or cutaneous food hypersensitivity
Contact dermatitis to topical ear products
Immune mediated disease
Miscellaneous
What are the secondary factors of canine otitis externa?
Bacteria - S. pseudintermedius, Pseudomonas, Proteus, Klebsiella, E. coli
Yeasts - Malassezia
What are the perpetuating factors of otitis externa?
Ear canal pathology including epidermal, dermal or adnexal changes
Stenosis of lumen
What do the perpetuating factors of canine otitis externa lead to?
Middle ear disease as the tympanic membrane is broken down
How does treatment for otitis media differ from otitis externa?
Need to switch to systemic treatment
What are the management aims of otitis externa?
Reverse the perpetuating factors
Resolve secondary infection
Address primary factors
Remove predisposing factors if you can
What are the characteristics of recurrent/chronic pruritic otitis externa?
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
How is recurrent/chronic pruritis otitis externa treated?
Removal of discharge and resolution/prevention of microbial complication
Effective control of allergic inflammation often required
What are the characteristics of chronic progressive purulent otitis?
Long-standing unresolved microbial infection that is multifactorial with soft tissue changes and/or otitis media
What are the characteristics of otitis media?
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
Which factors don’t rule out otitis media?
Tympanic membrane intact
Imaging normal
No neuro signs
How does acute OM progress to chronic OM?
Microbial shift from g+ve and Malassezia to g-ve especially Pseudomonas
Multiple partially effective/ineffective antimicrobial treatment attempts causing antimicrobial resistance
What are the key diagnostic points for ear infections?
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
What are the indications for surgical treatment of OE or OM?
Tumours or polyps
Irreversible stenosis
Aggressive medical treatment failed/not possible/not wanted
What is the medical approach to treatment of OE and OM?
Resolve current infection by assessing and reversing perpetuating factors and resolving infection
Prevent recurrence of infection through addressing primary factors and removing predisposing factors
How are perpetuating factors reversed?
Reverse stenosis, clean and examin ears under GA, home cleaning
How are ear infections resolved?
Topical and systemic antibiotics with topical being most important
How are primary factors addressed to reduce recurrence of OE and OM?
Investigate/control/resolve underlying diseases that are typically allergic
What are the first line topical antibiotic treatments for ears?
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
What are the second line topical antibiotic treatments for ears?
EASOTIC (g-ve, Malassezia) miconazole/gentamicin/hydrocortisone aceponate
OTOMAX (g-ve, malassezia) clotrimazole/gentamicin/betamethasone
What are the reserved topical antibiotic treatments for ears?
AURIZON clotrimazole/marbofloxacin/dexamethosone
POSATEX posaconazole/orbifloxacin/mometasone
What are the common causes of treatment failure of OE and OM?
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
What are the nine golden rules of ear disease treatment?
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
