Treating ear disease Flashcards
+ some miscellaneous ear diseases (38 cards)
Reasons to flush the ears
- Diagnostic and therapeutic
Ear flushing - diagnostic
- See epithelium of the ear canal
– Hyperplasia
– Ulceration
– Masses
– Defects (when the drum has been touched roughly, e.g. by a foreign body, red/brown bruising is seen) - Check integrity of the drum (gentle back & forth flushing can be used to highlight the drum)
– Very difficult to assess correct level of drum in many dogs
Ear flushing - therapeutic
- Dilutes and removes bacteria, yeasts and inflammatory mediators
- With appropriate cleaners anti-microbial effects
- Removes pus which may inactivate antibiotics
- Removes old treatments
Even in some apparently clean ears, material remains at the proximal end of the canal against the tympanum. This can be very firm, but recurrent otitis will continue unless removed.
Flushing solutions
Normal saline
- Safe, widely available
- Sterile
Squalene
- Oily liquid to dissolve waxy discharges
- Considered safe
Chlorhexidine (dilute)
- Known to be problematic at higher concentrations
- Considered safe in dogs – not known in cat. Use commercial products
- e.g. TRIZChlor (Dechra) and Otodine (Nextmune)
Others – for use after the drum is known to be intact
- cerumolytics emulsify ear wax for easy removal e.g. alcohols
- aqueous solutions aid in removing pus, mucus and serum from the ears
- Ear cleaning solutionsdrying agents decrease moisture in the ears and desiccate the surface keratinocytes e.g boric acid
Ear cleaning solutions - criteria for a product
- Cleaning power
- Antimicrobial action
- Potential for ototoxicity
Ear cleaning solutions
General purpose cleaner
- Use in some infections, maintenance cleaning
- May not be otosafe
Specific products
- Antimicrobial aqueous flush
– Used in purulent infections
– Considered otosafe
- Dewaxing cleaner
– Usually few antimicrobial properties, but dissolves wax
- Base for other therapies
– TRIZEDTA, to which antibiotics, steroids and other products are added. Little if any antimicrobial action
-Biofilm treatments
General purpose cleaners
- Cleanaural
- Epiotic
Cleanaural (pH 6.5)
Ingredients
- Boric acid
- Citric acid
- Isopropanol alcohol
- Propylene glycol
Properties
- Good cleaner
- Good antimicrobial properties
- Staph killed at 1/32 Pseudomonas killed at 1/8 and Malassezia killed at 1/32
However quite ‘stingy’ in inflamed ear
Unlikely to be ‘otosafe’
Epiotic (pH 7.0)
Ingredients
- Salicylic acid 0.1%
- Parachlorometaxylenol (PCMX) 0.1%
- Disodium EDTA & Docusate sodium and Propylene glycol base
- Monosaccharides (L-rhamnose, D-galactose and D-mannose)
Properties
- Fair to good cleaner
- Fair to good antimicrobial properties
– Staph killed at ½, Pseudomonas killed at 1/8 and Malassezia killed at 1/8
- Drying effect on the canal
- Comfortable in the ear
- Probably not otosafe (PCMX and docusate sodium)
- Slows the production of ceruminous secretions
Purulent otitis tx - Otodine (TRIZChlor) (pH 8.0)
Ingredients
- Tromethamine (Tris)
- Edetate disodium dihydrate (EDTA)
- Chlorhexidine 0.15%
Properties
- Watery cleaner
- Doesn’t sting
- Poor ceruminolytic action
- Good to fair antimicrobial properties
– Staph killed at 1/2
– Pseudomonas killed at 1/16
– Malassezia killed at 1/8
- Appears otosafe in the dog – data lacking for the cat
- Good for the inflamed ear and pus
Waxy (ceruminous) otitis tx - Cerumaural & Otoact (squalene-based cleaners)
Ingredients
- squalene
- isopropryl myristate, mineral oil (C)
- salicylic acid, chamomile, tannic acid (O)
Properties
- Dissolve and mobilise waxy, greasy discharge
- No antimicrobial properties
- Considered to be otosafe
- Cerumaural greasier than Otoact
TRIZ EDTA (pH 7.9)
Base for additions or as pre-flush
Ingredients
- Tromethamine (Tris)
- Edetate disodium dihydrate (EDTA)
Properties
- Poor ceruminolytic properties
- No antimicrobial activity (by itself)
- Appears otosafe
- Pre-treatment and base for other treatments only
Biofilm busting- TRIZ EDTA with added N-acetyl cysteine
Ingredients
- Tromethamine (Tris)
- Edetate disodium dihydrate (EDTA)
- N-acetyl cysteine
Properties
- Disrupts biofilm as N-acetyl cysteine breaks bonds in carb matrix
- Some antimicrobial activity
- Appears otosafe
- May be irritant in the inflamed ear
Available
- Vetruus – TRIS-NAC
- Homemade with Parvolex 200 mg/ml Concentrate for Solution for Infusion
Often used before other tx e.g. antibiotic cream
Anaesthesia
- In severe / chronic otitis, anaesthesia is needed to perform adequate flushing
- Endotracheal tube protects aspiration of flushing solution
- Hearing is often present with sedation
– Especially medetomidine - Adequately assess the ear
- Pain – can be very severe
- Otitis media common, but not diagnosed
Manual otoscope + syringe vs video otoscopy
Manual otoscope + syringe
- Spreul needle or better cut down gauge 6 urinary catheter
- Large catheter cover
- Precise, but time consuming
- Can make the ear sore through rubbing of speculum
- Equipment inexpensive
Video otoscopy
- Precise
- Able to record data if data capture technique
- Custom made curettes, biopsy and grabbing tools
- Small bore channel -> slow cleaning in some cases
- May not fit the smallest ears
Even with video otoscopy large chunks best removed manually
Treating OE - Plan
- Remove/reduce microbes
- Reduce swelling, discomfort or pain
- Normalise canal lumen and function
- Polypharmacy is the rule: medications contain
– Antibiotic
– Antifungal
– Anti-inflammatory agent - Except for Recicort (triancimalone)
Treating OE - Approach
- History
– Indications for atopic dermatitis, other diseases, FB etc - Examine ears
– Otodectes?
– Foreign body?
– Inflammatory otitis
– Cytology (± bacteriology) - Treat for 7-14 days
- Repeat examination
- Manage ear canal ? Consider underlying cause
Drugs that are ototoxic
- Gentamicin – rare using otic preparations (reduced in aqueous solutions)
- Polymixin B – rare
- Ticarcillin and imipenem – commonly seen, but should we be using these?
- Propylene glycol
- Chlorhexidine at moderate concentrations
- If have to use ototoxic otic products avoid concurrent use of drugs that might increase risk
– Frusemide and other loop diuretics
– Cis-platin
– Erythromycin
– NSAIDS
Erythroceruminous otitis
Clinically
- Red, waxy itchy ear
- Often a feature of allergic skin disease
Cytology shows cocci ± Malassezia, squames, but no neutrophils
- Microbial overgrowth
Treat
- Cleaner appropriate for the level of discharge
- Corticosteroid alone
Purulent otitis – acute
Clinical signs
- Redness, pruritus, pain and discharge
- May be secondary features of lichenification on the pinna
Cytology
- Neutrophils and bacteria (intra and extracellular)
Treatment
- First-line ointment based on cytology and otoscopy
- Once to twice daily therapy for 7-14 days
– Canaural / Surolan / Easotic
– Sufficient amount (0.7-1.0 mls for a large dog)
- Alternatively, Neptra or Osurnia (once or twice respectively)
- Combined with a suitable cleaner e.g.
– Otodine/TRIZChlor – watery, disinfectant & doesn’t sting
Purulent otitis – if severe
- Consider putting a charcoal swab in the fridge at time of the first appointment
- Send a swab off if rods regardless of time course
- If the ear is very swollen
– Steroids for 1-2 days before further otoscopic examination - If a large volume of discharge / unclear time course
– Admit for flush etc – treat as chronic case
Purulent otitis - Re-check
- Obligatory
– Improvement ?
– Owner compliance
– The next stage - May need to restore epithelial migration
– Period of cleaning beyond microbiological and anatomical cure - Identify underlying cause
Chronic allergic otitis
- Long term Malassezia and S. pseudintermedius dysbiosis and overgrowth
- Treat the ear prophylactically with steroids ± cleaner to prevent flares
- Currently no products with marketing authorization for this use
- Commonly used products include, Cortavance† (hydrocortisone aceponate spray), Recicort † (Triamcinolone drops), dexamethasone diluted in sterile water (0.25 mg /ml) or by adding dexamethasone to cleaning products †.
- This usually results in better overall control and prevents flares
† = not considered safe in the middle ear
Pseudomonas otitis
- Common problem (≥ 35% of OE &/or OM)
- Gram negative rod
- Highly drug resistant capsule and bacterial wall
- Constitutive resistance to many antibiotics
- Rapid development of resistance
- Often follow a poorly managed or untreated Malassezia or Staphylococcal otitis
- Swelling, pain, ulceration and malodour common
- Green to browny black discharge
- May be associated with
– immunosuppression
– Swimming
– Prior use of antibacterials
