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Y4 SA - Dermatology > Otitis 1 > Flashcards

Otitis 1 Flashcards

1
Q

Describe the tympanic bullae in dogs and cats

A

Cat – bony shelf that extends completely throughout the tympanic bullae, separating it into two halves – can make treatment difficult
In dogs it is more open

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2
Q

Which nerve is found in the middle ear?

A

Facial

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3
Q

Describe the histology of the ear canal

A

Ear canal lined by modified skin
Small hairs
Ceruminous glands
Sebaceous glands

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4
Q

Describe the histology of the middle ear

A

Middle ear lined by modified respiratory epithelium
Simple squamous to cuboidal
Few ciliated cells
Mucous-secreting goblet cells

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5
Q

Why do ears not need to be cleaned?

A

Self-cleaning mechanism - Only need to be cleaned when the ears are diseased and the self cleaning mechanism has stopped working

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6
Q

What is cerumen?

A

‘Ear wax’
- Sebaceous & ceruminous gland secretions
- Catches foreign material, desquamated keratinocytes & microbes
- Contains antimicrobial peptides and Igs

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7
Q

What are the two key features of the self-cleaning mechanism of the ear?

A

Cerumen
Epithelial migration - living keratinocytes carry cerumen and contents out of canal

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8
Q

What is the function of the Eustachian tube?

A

An opening that connects the middle ear with the nasal-sinus cavity:
- Drains mucous from middle ear cavity into nasopharynx
- Equalises air pressure either side tympanic membrane

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9
Q

Which microbes are normally present in the external ear canal?

A
  • Gram +ve cocci predominate: Staphylococcus pseudintermedius, S. schleiferi
  • Coagulase –ve staphylococci
  • Streptococcus spp.
  • Micrococcus spp.
  • Malassezia spp.
  • Middle ear commensals similar to URT flora
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10
Q

Name some causes of pruritic pinna disease

A
  • Sarcoptic mange (scabies)
  • Neotrombicula (harvest mites)
  • Allergic skin disease (CAD)
  • Pemphigus foliaceous
  • Contact irritant dermatitis
  • Fleas
  • Aural haematoma
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11
Q

Name some causes of non-pruritic pinna disease

A
  • Vasculitis
  • Pinnal margin seborrhoea
  • Squamous cell carcinoma
  • Hyperadrenocorticism and hypothyroidism
  • Pemphigus foliaceous
  • Auricular Chondritis
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12
Q

Define primary and secondary causes of otitis

A

Primary = induce otitis in normal ears
Secondary = promote otitis in abnormal ears

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13
Q

What are predisposing factors?

A

Present prior to otitis and make it more likely to develop

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14
Q

What are perpetuating factors?

A

Result from inflammation and prevent resolution

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15
Q

List the primary causes of otitis in dogs

A
  1. Foreign bodies - Plant awns, foxtail, hair, sand
  2. Allergic skin disease - atopic dermatitis, adverse food reaction, flea bite hypersensitivity, contact allergy
  3. Bugs - Otodectes, Demodex, trombiculids, ticks
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16
Q

List the primary causes of otitis in cats

A
  1. Flu - FCV, FHV, (FeLV, FIV), canine distemper
  2. Allergic skin disease - atopic dermatitis, adverse food reaction, flea bite hypersensitivity, contact allergy
  3. Bugs - Otodectes, Demodex, trombiculids, ticks
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17
Q

What is hypersensitivity otitis - how does it present?

A
  • OE common manifestation of AD
  • Pruritus present
  • May be history of generalised pruritic skin disease or only otitis
  • Dogs often meet Favrot’s criteria for diagnosis CAD either way but cats (FASS) may not
18
Q

What is the most common cause of foreign body otitis

A

Grass seeds most common
- Late spring – end of summer
- Acute onset, violent response
- Can be hidden in wax and migrate into middle ear
- Painful (chemical restraint required)
- Beware the hair that looks like grass seed and vice versa

19
Q

How does Otodectes cynotis present?

A
  • Dark ‘coffee ground’ wax, small white mites
  • Most patients have HSR to mites > intense pruritus
  • Ectopic disease (mites leave ear canal and affect haired skin e.g. tail tip in cats)
  • Mites photophobic so if not seen otoscopically sample ear
20
Q

How is Otodectes cynotis diagnosed?

A

Indirect smear using cotton bud
Collect wax from EEC
Mix with liquid paraffin on slide
Cover slip and microscopy x4

21
Q

How is Otodectes cynotis treated?

A
  • Most oily topical ear products effective with localised disease (smother mites)
  • Selamectin or moxidectin spot-on
  • Evidence that isoxazoline group effective*
  • May need steroids to manage inflammation and pruritus
22
Q

List some secondary causes of otitis

A
  • Microbial infection
  • Topical medication reaction (Irritation of inflamed skin by alcohol, acid, propylene glycol)
  • Inappropriate cleaning (Physical trauma, excessive moisture and maceration)
23
Q

List a predisposing factor for obstructive ear disease

A

Neoplasia and polyps

24
Q

How can conformation of ears act as a predisposing factors for ear disease?

A

Hairy canals (e.g. poodle)
Narrow canals (e.g. Shar pei)
Waxy canals and hairy pinnae (cocker spaniel)
Pendulous pinnae (e.g. bloodhound)

25
Q

How can the patients environment act as a predisposing factors for ear disease?

A

Water (swimming, groomers, cleaners)
High temperature and humidity

26
Q

How can systemic disease act as a predisposing factors for ear disease?

A

Immune suppression, debilitation

27
Q

Describe the progressive pathological changes that can take place within an ear

A
  • Failure of epithelial migration
  • Progressive epithelial hyperplasia, oedema, fibrosis & folding
  • Glandular dilation and hyperplasia
  • Canal stenosis
  • Rupture of tympanum
  • Calcification of pericartilaginous tissue
  • Osteomyelitis
  • Para-aural abscessation
28
Q

Describe how to approach an otoscopic exam

A
  • Always check both ears! - Owners more commonly bring patients in for unilateral otitis
  • Assess and palpate (gently): Pinnae, External ear canals (non-painful, pliable, moveable)
  • Otoscopy
29
Q

Describe the otoscopic exam

A
  • Need VN/owner to restrain animal
  • NB if painful, may not be possible (admit for chemical restraint or treat and recheck)
  • Strong light, small cone to reduce contact with epithelium
  • Gently pull pinna to straighten EEC
  • Epithelium should be pale and smooth, canal open (NB stenotic breeds Shar Pei, FBD, Pug), little wax
30
Q

List the clinical signs of otitis externa

A
  • Otic pruritus: scratching, rubbing, headshaking
  • Pain
  • Discharge (otorrhea), malodour
  • Loss of hearing
  • Secondary changes: pinnal erythema, lichenification, scaling, pyotraumatic dermatitis, aural haematoma
31
Q

List the signs of otitis externa seen on the otoscopic exam

A

Epithelial erythema, hyperplasia, erosion/ulceration, fibrosis, stenosis of EEC

32
Q

Malassezia over growth in ears commonly leads to..?

A

staphylococci overgrowth or infection

33
Q

Describe gram –ve rod (usually Pseudomonas) infection in ears

A
  • As moisture/humidity increases
  • Cant just treat topically, need to get rid of the inflammatory change to completely stop from reoccurring
  • Chronic Pseudomonas OE commonly progresses to OM in dogs (less commonly OI)
34
Q

List the clinical signs of otitis medial and internal

A

Clinical signs of otitis external plus
- Pain
- Horner’s syndrome
- Loss of hearing
- Vestibular disease

35
Q

What are the signs of Horner’s syndrome?

A

Protrusion of the 3rd eyelid
Upper eyelid drooping
Decreased pupil size
Sweating on the affected side

36
Q

What are the signs of vestibular disease?

A

Ataxia +/- falling
Head tilt to affected side
Spontaneous/rotary nystagmus
Anorexia/vomiting

37
Q

Which dogs most commonly present with primary otitis media?

A

Brachycephalic breeds

38
Q

Describe the aetiology of primary otitis media in dogs

A

Haematogenous spread (infectious) vs breed related conformation abnormality e.g. Eustachian tube dysfunction?

39
Q

What is the most common cause of primary otitis media in cats?

A

Nasopharyngeal polyps
- Invade Eustachian tube and middle ear

40
Q

Describe the main features of primary secretory otitis media

A
  • Mucous build up in middle ear
  • Aetiology unclear - Eustachian tube dysfunction?
  • Present for deafness or pain or incidental finding on CT/MRI
  • Bulging TM on otoscopy
  • Myringotomy to sample for cytology
  • Repeated flushing with sterile water eventually liberates large mucous plug

Y4 SA - Dermatology (6 decks)

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