Otitis 2 Flashcards

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1
Q

When is MRI used in otitis cases?

A

MRI reserved for animals presenting with neurological signs (where more detailed assessment of inner ear and brain required) or where soft tissue surgical planning required (assess for para-aural abscessation)

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2
Q

Describe the uses of radiography for otitis

A

Most widely available
Potential to ID
- mineralisation of EEC cartilages
- Fluid lines, osteolysis & bony proliferation in bullae
Cant be used to confirm otitis media

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3
Q

Describe the uses of CT for otitis cases

A

Imaging modality of choice for chronic otitis cases without neurological signs
Good assessment of
- EEC: thickening and stenosis, mineralisation
- Bony structures: bony change affecting tympanic bulla
- Middle ear: sensitive for diagnosis OM
- Inner ear: OI may be ID but less info on soft tissue (brain) involvement
- Bullae should be completely black (air filled)
Quicker and cheaper than MRI (may be quicker than radiography)

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4
Q

Describe the uses of MRI for otitis cases

A

Far better appreciation of soft tissue structures
- Meningeal involvement with OI
- Para-aural abscess with severe, chronic OE
Expensive: will take significant part of client’s budget!

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5
Q

What if I don’t have CT/MRI or my client can’t afford it??

A

Assessment for OM: myringotomy

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6
Q

Which techniques provide the most accurate way of assessing otitis media?

A

Myringotomy plus cytology - requires skill and experience

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7
Q

What is myringotomy?

A

A myringotomy is a procedure to create a hole in the ear drum to allow fluid that is trapped in the middle ear to drain out. The fluid may be blood, pus and/or water. In many cases, a small tube is inserted into the hole in the ear drum to help maintain drainage.

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8
Q

List the indications for a myringotomy

A
  • Bulging eardrum on otoscopy with pain or neurological signs (Horner’s syndrome, vestibular disease, facial paresis)
  • Radiographic/CT/MRI bulla changes and intact eardrum
  • Evidence of fluid/tissue behind eardrum (requires experience of assessing eardrum)
  • Medically unresponsive vestibular disease with an intact eardrum
  • Chronic OE cases > 6 months failing to respond to treatment (requires judgement)
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9
Q

Why is it important to clean ears in otitis cases?

A

Majority of otitis cases benefit from cleaning
- Removal of infectious debris & disruption of microbial biofilms
- Visualisation of TM
- Assess epithelium: hyperplasia, ulceration, defects
- Expose and/or sample otic polyps/tumours
- Enhance action of topical therapy

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10
Q

The method of ear cleaning depends on which factors?

A

Severity of otitis (stenosis, pain)
Type and volume of discharge
Client factors e.g. finances
Patient factors e.g. TM rupture

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11
Q

How is ear cleaning done in cases of acute otitis with no pain and minimal debris?

A

Conscious animal
Proprietary cleaner (check TM)

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12
Q

How is ear cleaning done in cases of chronic otitis with copious discharge?

A
  • General anaesthesia, intubation
  • Handheld vs video otoscope
  • Lavage with sterile water/saline until TM seen to be intact
  • Post cleaning analgesia (paracetamol 10mg/kg q8hrs 3 days)
  • Pre-treatment with prednisolone
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13
Q

Name some available ear cleaners

A

Otodine
Otoact
Otoprof
TrizChlor
TrizAural

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14
Q

What are biofilms? How do they affect otitis?

A

Microbes stuck together in extracellular matrix
Protected environment, infection difficult to treat

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15
Q

How are biofilms in otitis treated?

A
  • N-acetylcysteine (Tris-NAC®), Betaine/polyhexanide (Prontosan® Wound Irrigation Solution)
  • Disrupt biofilm and reduce viability of Staphylococcus spp. and Pseudomonas spp.
  • Sterile water/saline lavage, instill product, massage (< 5 mins)
  • Remove by suction, thoroughly lavage with sterile saline
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16
Q

Describe the uses of NSAIDs for otitis

A

Waste of time for ears

17
Q

Which drugs are used for their anti-inflammatory properties in ears?

A

Corticosteroids
- Anti-pruritic, decrease glandular secretions, exudation, scar tissue & proliferative changes
- Systemic prednisolone, methylprednisolone
- Topical prednisolone, dexamethasone, betamethasone, HCA

18
Q

Describe the uses of cytology for otitis cases

A
  • Cheap, easy, low risk, conscious animal, in house interpretation, rapid results
  • Required to diagnose microbial overgrowth & infection (not culture)
  • Differentiate sterile inflammation & infection
  • Informs empirical topical therapy
  • Assesses response to therapy
19
Q

Describe how to use cytology to sample the external ear canal

A

Indirect smear using cotton bud
Roll on to slide, air dry
Modified Wright-Giemsa stain (Diff-Quik)
Microscopy x4, x40, x100 oil immersion

20
Q

How is cytology used to sample the middle ear?

A
  • Otoscopic (ideally video) guidance
  • Insert (cut off) urinary catheter into middle ear (caudoventral quadrant)
  • Gently suction small amount using syringe
  • Spray onto slide and smear using cotton bud or another slide, air dry
  • Staining and microscopy as before
21
Q

How would a Malassezia overgrowth appear on cytology?

A

Large numbers corneocytes and budding yeasts (no inflammatory cells)

22
Q

Chlorhexidine is used to treat which types of infections?

A

G+ve cocci, G-ve rods, Malassezia

23
Q

Polymixin B, marbofloxacin and gentamicin are used to treat which causes of otitis?

A

G+ve cocci, G-ve rods

24
Q

Clotrimazole, miconazole and nystatin are used to treat which cause of otitis?

A

Malassezia

25
Q

Which features of antibiotic stewardship need to be considered when treating otitis?

A

Use antiseptic
Use narrowest spectrum AM to do the job
Avoid 2nd and 3rd line antibiotics unless necessary

26
Q

When are topical antimicrobials not licenced?

A

When there is a ruptured ear drum

27
Q

Name two log acting preparations

A

Neptra
Osurnia

28
Q

Proprietary topical antimicrobials have a combination of which treatments?

A

Steroid
Antibiotic
Antifungal

29
Q

If the ear drum cant be seen how can you treat otitis?

A

No treatment licensed for use with ruptured TM
Many proprietary drops ototoxic, options include:
- Treat 1-2 wks with systemic prednisolone & recheck
- Clean ear (ideally GA) & recheck
- Treat with ‘safe’ water-based product & recheck

30
Q

Name some ‘safe’ water-based products that can be used when theres a ruptured TM

A
  • TrizChlor, Otodine
  • TrizAural combined with GC and antibiotic
  • TrisEDTA useful for Gram –ve infections; potentiates AM by damaging bacterial cell wall
31
Q

When is culture and sensitivity used for otitis?

A
  • Least informative test for otitis
  • Should only be interpreted alongside cytology
  • Confirms infection following aseptic sampling of a sterile site
  • Used alone, not diagnostic for skin/otic infection
32
Q

When is culture and sensitivity indicated?

A
  • When infection confirmed cytologically and wish to know species of bacteria
  • When systemic antimicrobials required (OI, para-aural abscess)
  • Cases not responding to appropriate treatment
    ! Do not use for assessing response to therapy !
33
Q

How can you practice good antimicrobial stewardship when treating otitis?

A
  1. Avoid unnecessary AM use (confirm infection)
  2. Control inflammation
  3. Avoid systemic AM, use topical antiseptic if possible
  4. Narrow spectrum, correct dose, frequency, duration
34
Q

How could you treat a Pseudomonas infection with middle ear involvement?

A
  • Need to use water-based product and avoid ototoxic AMs
  • Activity against G-ve rods and safe (but not licensed): silver sulfadiazine, enrofloxacin, marbofloxacin
  • TrisEDTA to damage bacterial cell wall and potentiate AM
  • Potent, water-based glucocorticoid
  • Check q2wks, repeat cytology
35
Q

How would you treat Otitis with cocci overgrowth/infection on cytology?

A
  • Chlorhexidine, Tris-EDTA
    or
  • Fucidic acid, Framycetin, Nystatin, Prednisolone
36
Q

How would you treat Otitis with inflamed, itchy ears with no microbes on cytology

A

Triamcinolone

37
Q

Describe long term management of otitis cases

A

Therapeutic plan for primary factor(s)
Address any predisposing factors
Regular (1-2 x weekly) ear cleaning

38
Q

Describe hypersensitivity otitis

A

OE common manifestation of CAD
Must treat allergic inflammation to prevent recurrence

39
Q

How is hypersensitivity otitis treated?

A

Nothing licensed (long term), options include:
- Recicort (triamcinolone) licensed for 7 days only
- Cortavance (HCA) not licensed for use in ear (appears safe so long as ear drum intact)
- Dexadresson (dexamethasone) solution for injection applied topically or added to cleaners