Ear disease Flashcards
Predisposing factors - ear disease
- conformation
- obstruction
- excess (moisture, cerum, hair)
- cornification disorders
- immuno suppression
Primary factors causing ear inflammtion leading to ear disease
- FB
- parasites
- hypersensitivity (AD, cutaneous food hypersensitivity)
- contact dermatitis (topical ear products)
- (immune - mediated)
- (misc)
Secondary factors that contribute to pathology in ear disease
- BACTERIA (S. pseudintermedius, Pseudomonas, Proteus, Klebsiella and E.coli in more chronic cases)
- YEAST (Malassezia)
Name 3 types of tissue that can lead to ear canal stenosis
- epidermal
- dermal
- adnexal1
Define OM/ otitis media
middle ear disease (when tympanic membrane is eroded away)
4 management aims - ear disease
- reverse perpetuating factors
- resolve secondary infection
- address primary factors
- (remove predisposing factors)
What are the 2 manifestations of canine otitis
- recurrent/ chronic PRURITIC otitis externa
- chronic/ progressive PURULENT otits
Outline recurrent/ chronic pruritis otitis externa
- allergic skin disease*
- scondary bacterial/yeast/mixed overgrowth
- bilateral (not always concurrent or same severity)
- Pinnae, meatus, canal or all
- remove discharge and resolve/ prevent microbial complication
- effective control of allergic inflammation often required
- not necessarily progress to chronic infectious form
Outline chronic progressive purulent otitis
- long standing unresolved microbial infection
- multi factorial
- soft tissue changes and/or OM
- may become irreversible
How often is the tympanic membrane (TM) intact in OM ears?
often - about 73 % cases
T/F: OM is often accompanied by otitis externa (OE)
True
What causes the shift from acute to chronic infectious otitis?
MICROBIAL SHIFT: Gram + and malassezia to gram -(Pseudomonas), Malassezia alone also seen
Diagnostics - ear infections
- cytology (indespensible) (bacterial culture, interpret, nature of inflammation)
- culture doesnt replace cytology
- discordant microbial involvements at different sites
- poor repeatability of ear swab cultures
Indications - sx tx of ear disease
- tumours, polpys
- irreversible stenosis
- aggressive medical tx
Medical approach to tx of otitis
- RESOLVE CURRENT INFECTION:
1. assess and reverse perpetuating factors (Reverse stenosis, clean and examine, home cleaning)
2. resolve infections (topical, systemic) - PREVENT RECURRENCE OF INFECTION
3. assess primary factors
4. remove predisposing factors (if possible)
Common causes of tx failure
- not long enough
- inadequate ear cleaning
- fialure to ID and tx OM and soft tissue changes
- failure to ID and control primary cause of otitis
T/F: aural lavage must always be done under GA
True
Where should you sample in the ear?
most proximal site affected
T/F systemic ABs often not effective in ear disease
True
T/F conventional bacterial sensiticity testing is of great value for topical tx
False - it is of little value
Which products have human reserve ABs?
Aurizon and Posatex
When should antimicrobial tx be stopped??
don’t stop until complete clinical and microbiological cure
Systemic adverse effects of ear tx
- GCs
- basal cortisol
- ACTH stim
- T4
- insulin
Adverse effects outer ear
- occlusion
- maceration
- epidermal turnover and migration
- glandular changes
- micro FB formation
- atrophic effects
Adverse effects - middle ear
- facial nerve (including PS fibres) damage
- sympathetic neurons for ocular innervation (Horners)
- OM and cholesteatoma
What is cholesteatoma?
destructive and expanding growth consisting of keratinising squamous epithelium in middle ear and/or mastoid process
Ear specifci AEs of otic medication
- effects on inner ear (hearing and balance) = ototoxicity (due to diffuse from outer and middle ear via round window into inner ear), may occur weeks later
- seems rare
