Otitis 2 Flashcards
When is MRI used in otitis cases?
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)
Describe the uses of radiography for otitis
Most widely available
Potential to ID
- mineralisation of EEC cartilages
- Fluid lines, osteolysis & bony proliferation in bullae
Cant be used to confirm otitis media
Describe the uses of CT for otitis cases
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)
Describe the uses of MRI for otitis cases
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!
What if I don’t have CT/MRI or my client can’t afford it??
Assessment for OM: myringotomy
Which techniques provide the most accurate way of assessing otitis media?
Myringotomy plus cytology - requires skill and experience
What is myringotomy?
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.
List the indications for a myringotomy
- 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)
Why is it important to clean ears in otitis cases?
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
The method of ear cleaning depends on which factors?
Severity of otitis (stenosis, pain)
Type and volume of discharge
Client factors e.g. finances
Patient factors e.g. TM rupture
How is ear cleaning done in cases of acute otitis with no pain and minimal debris?
Conscious animal
Proprietary cleaner (check TM)
How is ear cleaning done in cases of chronic otitis with copious discharge?
- 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
Name some available ear cleaners
Otodine
Otoact
Otoprof
TrizChlor
TrizAural
What are biofilms? How do they affect otitis?
Microbes stuck together in extracellular matrix
Protected environment, infection difficult to treat
How are biofilms in otitis treated?
- 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
Describe the uses of NSAIDs for otitis
Waste of time for ears
Which drugs are used for their anti-inflammatory properties in ears?
Corticosteroids
- Anti-pruritic, decrease glandular secretions, exudation, scar tissue & proliferative changes
- Systemic prednisolone, methylprednisolone
- Topical prednisolone, dexamethasone, betamethasone, HCA
Describe the uses of cytology for otitis cases
- 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
Describe how to use cytology to sample the external ear canal
Indirect smear using cotton bud
Roll on to slide, air dry
Modified Wright-Giemsa stain (Diff-Quik)
Microscopy x4, x40, x100 oil immersion
How is cytology used to sample the middle ear?
- 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
How would a Malassezia overgrowth appear on cytology?
Large numbers corneocytes and budding yeasts (no inflammatory cells)
Chlorhexidine is used to treat which types of infections?
G+ve cocci, G-ve rods, Malassezia
Polymixin B, marbofloxacin and gentamicin are used to treat which causes of otitis?
G+ve cocci, G-ve rods
Clotrimazole, miconazole and nystatin are used to treat which cause of otitis?
Malassezia
Which features of antibiotic stewardship need to be considered when treating otitis?
Use antiseptic
Use narrowest spectrum AM to do the job
Avoid 2nd and 3rd line antibiotics unless necessary
When are topical antimicrobials not licenced?
When there is a ruptured ear drum
Name two log acting preparations
Neptra
Osurnia
Proprietary topical antimicrobials have a combination of which treatments?
Steroid
Antibiotic
Antifungal
If the ear drum cant be seen how can you treat otitis?
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
Name some ‘safe’ water-based products that can be used when theres a ruptured TM
- TrizChlor, Otodine
- TrizAural combined with GC and antibiotic
- TrisEDTA useful for Gram –ve infections; potentiates AM by damaging bacterial cell wall
When is culture and sensitivity used for otitis?
- 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
When is culture and sensitivity indicated?
- 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 !
How can you practice good antimicrobial stewardship when treating otitis?
- Avoid unnecessary AM use (confirm infection)
- Control inflammation
- Avoid systemic AM, use topical antiseptic if possible
- Narrow spectrum, correct dose, frequency, duration
How could you treat a Pseudomonas infection with middle ear involvement?
- 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
How would you treat Otitis with cocci overgrowth/infection on cytology?
- Chlorhexidine, Tris-EDTA
or - Fucidic acid, Framycetin, Nystatin, Prednisolone
How would you treat Otitis with inflamed, itchy ears with no microbes on cytology
Triamcinolone
Describe long term management of otitis cases
Therapeutic plan for primary factor(s)
Address any predisposing factors
Regular (1-2 x weekly) ear cleaning
Describe hypersensitivity otitis
OE common manifestation of CAD
Must treat allergic inflammation to prevent recurrence
How is hypersensitivity otitis treated?
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
