Ear disease

Question 1

Predisposing factors - ear disease

Answer 1

• conformation
• obstruction
• excess (moisture, cerum, hair)
• cornification disorders
• immuno suppression

Question 2

Primary factors causing ear inflammtion leading to ear disease

Answer 2

• FB
• parasites
• hypersensitivity (AD, cutaneous food hypersensitivity)
• contact dermatitis (topical ear products)
• (immune - mediated)
• (misc)

Question 3

Secondary factors that contribute to pathology in ear disease

Answer 3

• BACTERIA (S. pseudintermedius, Pseudomonas, Proteus, Klebsiella and E.coli in more chronic cases)
• YEAST (Malassezia)

Question 4

Name 3 types of tissue that can lead to ear canal stenosis

Answer 4

• epidermal
• dermal
• adnexal1

Question 5

Define OM/ otitis media

Answer 5

middle ear disease (when tympanic membrane is eroded away)

Question 6

4 management aims - ear disease

Answer 6

• reverse perpetuating factors
• resolve secondary infection
• address primary factors
• (remove predisposing factors)

Question 7

What are the 2 manifestations of canine otitis

Answer 7

• recurrent/ chronic PRURITIC otitis externa

- chronic/ progressive PURULENT otits

Question 8

Outline recurrent/ chronic pruritis otitis externa

Answer 8

• 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

Question 9

Outline chronic progressive purulent otitis

Answer 9

• long standing unresolved microbial infection
• multi factorial
• soft tissue changes and/or OM
• may become irreversible

Question 10

How often is the tympanic membrane (TM) intact in OM ears?

Answer 10

often - about 73 % cases

Question 11

T/F: OM is often accompanied by otitis externa (OE)

Answer 11

True

Question 12

What causes the shift from acute to chronic infectious otitis?

Answer 12

MICROBIAL SHIFT: Gram + and malassezia to gram -(Pseudomonas), Malassezia alone also seen

Question 13

Diagnostics - ear infections

Answer 13

• cytology (indespensible) (bacterial culture, interpret, nature of inflammation)
• culture doesnt replace cytology
• discordant microbial involvements at different sites
• poor repeatability of ear swab cultures

Question 14

Indications - sx tx of ear disease

Answer 14

• tumours, polpys
• irreversible stenosis
• aggressive medical tx

Question 15

Medical approach to tx of otitis

Answer 15

• 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)

Question 16

Common causes of tx failure

Answer 16

• 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

Question 17

T/F: aural lavage must always be done under GA

Answer 17

True

Question 18

Where should you sample in the ear?

Answer 18

most proximal site affected

Question 19

T/F systemic ABs often not effective in ear disease

Answer 19

True

Question 20

T/F conventional bacterial sensiticity testing is of great value for topical tx

Answer 20

False - it is of little value

Question 21

Which products have human reserve ABs?

Answer 21

Aurizon and Posatex

Question 22

When should antimicrobial tx be stopped??

Answer 22

don’t stop until complete clinical and microbiological cure

Question 23

Systemic adverse effects of ear tx

Answer 23

• GCs
• basal cortisol
• ACTH stim
• T4
• insulin

Question 24

Adverse effects outer ear

Answer 24

• occlusion
• maceration
• epidermal turnover and migration
• glandular changes
• micro FB formation
• atrophic effects

Question 25

Adverse effects - middle ear

Answer 25

- facial nerve (including PS fibres) damage - sympathetic neurons for ocular innervation (Horners) - OM and cholesteatoma

Question 26

What is cholesteatoma?

Answer 26

destructive and expanding growth consisting of keratinising squamous epithelium in middle ear and/or mastoid process

Question 27

Ear specifci AEs of otic medication

Answer 27

- 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