otitis externa

Question 1

List 4 important predisposing factors in otitis

Answer 1

1. Conformation: hairy/stenotic canals, pendulous pinnae
2. XS wetting of the ear canal: heat/humidity factors, swimming
3. Obstructive ear disease: neoplasia, polyps
4. Tx effects: inappropriate cleaning solutions, traumatic cleaning + plucking

Question 2

What type of ear cleaners should you avoid in sensitive ears?

Answer 2

avoid acidic potent ceruminolytics and astringent ear cleaners

Question 3

What are your 5 primary causes of otitis externa?

Answer 3

1. Allergy: atopy, food, contact
2. Endocrine: HypoT
3. Autoimmune/immune-mediated
4. Keratinisation disorders
5. Ectoparasites: Otodectes cynotis, Demodex sp.

Question 4

What conditions may benefit from ear drops containing glucocorticoids?

Answer 4

Allergic, immune-mediated primary causes

Question 5

Give an example of a potent topical glucocorticoid

Answer 5

Mometasone, hydrocortisone aceponate

Question 6

Give an example of a potent ceruminolytic

Answer 6

carbamide peroxide, sodium docusate, squalene

Question 7

Give an example of a miticidal potentially found in ear drops

Answer 7

avermectins, permethrin, thiabendazole, rotenone

Question 8

How may your cleaning solution differ when treating a dog with sebaceous adenitis vs. primary idiopathic seborrhoae?

Answer 8

1. SA = dry ears –> tx/ w/ oil based

2. PIS = needs a potent ceruminolytic

Question 9

Give 2 examples of immune-mediated primary causes of otitis externa

Answer 9

Pemphigus foliaceus, bullous pemphigoid

Question 10

Give a gram +ve and gram -ve bacteria that act as secondary causes of otitis externa

Answer 10

Gram +ve: Staph, strep, enterococcus, corynebacterium

Gram -ve: Pseudomonas

Question 11

List 2 perpetuating factors in otitis

Answer 11

1. Pathological changes in the external ear canal

2. Otitis media

Question 12

What is fusidic acid?

Answer 12

a narrow spectrum bacteriostatic antimicrobial

Question 13

Fusidic acid targets…

Answer 13

Staph (+ methicillin-resistant strains), Corynebacterium, Anaerobes

Question 14

List 3 aminoglycosides

Answer 14

Neomycin, Gentamicin, Framycetin, Amikacin

Question 15

ID two disadv. of Neomycin (vs. other aminoglycosides)

Answer 15

1. Least potent

2. Common cause of contact allergy

Question 16

List 3 bacteria targeted by Amikacin

Answer 16

Staph, Corynebacterium, Pseudomonas

Question 17

List 4 bacteria targeted by Gentamicin

Answer 17

Staph, Corynebacterium, Proteus, E.coli, Pseudomonas

Question 18

Which aminoglycoside is the first line drug when cocci ID on cytology?

Answer 18

Neomycin

Question 19

List 3 fluoroquinolones

Answer 19

Enro, Marbo, Cipro, Orbifloxacin

Question 20

What bacteria do fluoroquinolones target?

Answer 20

Gram -ve bacilli and Gram +ve cocci

Question 21

How does miconazole affect the spectrum of Polymxin B?

Answer 21

Polymxin usu targets gram -ve bacilli, but acts synergistically with miconazole to also target Gram +ves.

Question 22

What bacteria are targeted by Silver sulphadiazine?

Answer 22

Methicillin-res. Staph and Pseudomonas

Question 23

What does florfenicol target?

Answer 23

Gram +ve (staph, enterococcus, corynbacterium) and -ve (proteus)

Question 24

What does Ticarcillin target?

Answer 24

P.aeruginosa.