23.11.4: Ear disease 1 Flashcards
From lecture on 2/3/2023
1
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Otitis externa
A
inflammation of the outer ear
2
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Otitis media
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inflammation of the middle ear
3
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Otitis interna
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inflammation of the inner ear (see neurology)
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21
Q
What components form cerumen and how does it move out of the ear? How can this be interfered with?
A
Cerumen = lipids + sloughed keratinocytes
* Cerumen also traps small FB, and acts as anti-bacterial, anti-yeast, and buffers changes in pH well
* Epithelial migration moves wax from the typical membrane to the external space
* Epithelial migration is disturbed by inflammation, wetness, hyperplasia, and physical blockage
22
Q
What factors can cause microbial overgrowth (dysbiosis) in the ear? Which microorganisms commonly overgrow?
A
Factors causing dysbiosis:
* Humidity
* Inflammation and swelling
* Reduced epithelial migration
* Epithelial surface changes
Most commonly these overgrow:
* Staphylococcus pseudintermedius
* Malassezia pachydermatitis
23
Q
What is P.S.P.P. and how does it help us in treating otitis?
A
- If we have a combination of these factors, we will see greater and longer-lasting disease.
- Considering each of these factors allows targeted assessment (cytology, C&S, underlying cause) and direct targeted treatment
24
Q
What are some predisposing causes to otitis?
A
25
**True/false:** ear plucking is essential in dogs with a history of otitis.
**False.**
* Ear plucking can cause trauma; steroids are preferable to reduce inflammation but these cannot be dispensed by groomers
* Owners can take the hairs that come away easily, but should not yank hairs out
26
Primary causes of otitis
**Parasites**
* *Otodectes cynotis*
* *Demodex* spp.
* Scabies
**Foreign bodies** e.g. grass awns
**Hypersensitivity**
* Atopic dermatitis
* Food hypersensitivity
* Medications
**Keratinisation disorders**
* Primary idiopathic seborrhea
* Hypothyroidism
**Glandular disorders**: some breeds have increased ceruminous glands
**Miscellaneous** e.g. feline proliferative and necrotising otitis externa
27
Which breeds have increased ceruminous glands, disorders of which can represent a primary cause of otitis?
* Cocker spaniels
* English Springer spaniels
* Labrador retrievers
28
Which parasites might cause ear and tail base disease in cats and why is this?
*Otodectes cyanotis*
This is due to the way cats curl up when they sleep
29
What is this and how would you treat?
*Otodectes cyanotis*
* Common cause of otitis
* May also cause hypersensitivity disease in some patients
* Run away from light and the otoscope
Treatment
* Most ear creams are effective against localised disease
* Moxidectin / selamectin spot on work
* Likely that isoxazolines also effective
* May need a cleaner ± steroids
30
What history and clinical exam findings would you expect from a dog with an otic foreign body?
* Late spring to early summer
* Sudden onset, violent response
* Very painful and bothering the dog greatly; however, compared to atopy, there are not many external signs
* Chemical restraint often essential to examine eat
* Foreign body may be hidden in discharge or migrate into the middle ear
31
How common is hypersensitivity otitis externa and how should it be prevented?
Otitis externa is a very common complication of atopic dermatitis and food allergy. It is often inadequately recognised and not treated until it is severe/ there is secondary infection.
Prevention of recurrence:
* Treat the primary disease
* Ensure perpetuating factors are treated
* Ensure the owner knows to intervene early
32
Hypersensitivity otitis externa
33
**True/false:** gram positive rods are normal in the ear.
**True** but not in large amounts.
34
Clinical signs of otitis externa
* Aural / otic pruritus, headshaking
* Mild to marked exudate
* Malodour
* Head tilt: may be neuro or pain
* Deafness: may be toxic or neuro
On clinical exam:
* Erythema, swelling, scaling, discharge (otorrhea), malodour, pain
* Secondary: pinnal lesions common, pyotraumatic dermatitis, haematoma
35
Which bacteria can cause acute secondary disease in the ear? (1)
36
Which gram +ve bacteria can cause chronic secondary disease in the ear? (2)
37
Which gram -ve bacteria can cause chronic secondary disease in the ear? (3)
38
Which fungi can cause secondary disease in the ear?
39
What are some perpetuating factors that contribute to otitis? (1-4)
40
What is present on cytology?
*Malassezia*
41
What is present on cytology?
Rods, possibly also some *Malassezia*
42
Describe how as disease progresses, microorganisms within the ear change
* Initially, may see *Malassezia* overgrowth
* After this, may see staphylococci, and then gram -ve rods
* In many cases, *Pseudomonas aeruginosa* is the endpoint
43
Progressive pathological changes that occur with time in the untreated / unsuccessfully treated ear
* Epidermal hyperkeratosis and hyperplasia
* Dermal oedema
* Fibrosis
* Ceruminal gland hyperplasia and dilation
* Abnormal epithelial cell migration
* Tympanic membrane alterations
* Otitis media (happens in 16% of acute and 50-80% of chronic otitis externa)
44
Clinical signs of otitis media
Variable clinical signs - often vague
* Non specific signs may be due to pain
* Often, concurrent otitis externa is the most obvious sign
* Deafness
* Yawning
* Pain on eating
* Signs of otitis interna if progression
* Damage to nerves running through middle ear (e.g. facial nerve) leads to more obvious signs
* Pictured: Horner's syndrome - can occur with otitis media or interna
45
Consequences of otitis media
Conductive deafness
* Loss of drum (animals have normal hearing with single hole in tympanic membrane)
* High pressure fluid / mucus in the iddle ear
* Chronic otitis externa / otitis media ± cholesteatoma
Horner's syndrome / facial paralysis
* Ear and lip droop, asymmetrical lips, dribbling
* Keratoconjunctivitis sicca, neurogenic dry nose
* Anisocoria with ipsilateral miosis, ptosis of upper eyelid
Vestibular syndrome (otitis interna)
46
Investigation of otitis media
* Appearance of drum on otoscopy
* Sampling of middle ear for bacteriology, fungal culture, cytology via myringotomy or ruptured tympanic membrane
* Palpation of granulation tissue in the middle ear
* BAER (hearing testing)
* Imaging e.g. CT
47
Treatment of otitis media
Intact drum:
* Perform myringotomy and flush until clean
Using C&S and culture data:
* Use aqueous antibiotics 2-3 times per day following cleaning with saline or an appropriate cleaner e.g. TRIZEDTA with 0.15 w/w chlorhex in dogs
* Pain relief
* Systemic antimicrobials not typically used
Severe cases
* Consider total ear canal ablation (TECA) ± OR bulla osteotomy
* Seek advice from experienced or referral vets
48
What would constitute a severe case of ear disease where you might consider TECA ± BO?
* Poor response to therapy
* Intractable otitis externa
* Evidence of marked new bone on radiographs / CT
49
What is **Primary secretory otitis media** and which breeds is it seen in? What are the clinical exam findings and treatment options?
Seen in CKCS and other brachys
* Present for deafness or neck pain; can be mistaken for syringomyelia
* There is marked mucoid build-up in middle ear
* Bulging middle ear noted on otoscopy
* Repeated flushing and myringotomy (3-5 times) will help for 18 months
* Sputolysin (a mucolytic) and N-acetyl-cysteine have been used by some; steroids are used to reduce mucus proliferaton but these do have adverse effects
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Indications for myringotomy
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Imaging modality used and 1 & 2
CT
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Imaging modality, species, findings
MRI
Dog
Normal - air in the bulla
53
Imaging modality, species, findings
54
Compare the use of MRI and CT for imaging the ear
CT = £1200-1800
MRI = £3000-4000
* MRI offers far better appreciation of soft tissue structures and should be considered when there may be wider neurological diagnoses
* CT is often as useful and a much cheaper alternative in many cases
55
Causes of otitis interna
* Extension of otitis media (majority of cases)
* Haematogenous and ascending infection via the auditory tube
* Adverse drug reaction
56
Clinical signs of otitis interna
* Head tilt to the affected side
* Spontaneous or rotatory nystagmus
* Asymmetric limb ataxia with preservation of strength
* Falling
* Vomiting ± anorexia
57
Differential diagnoses for otitis interna
* Other peripheral vestibular diseases
* Idiopathic vestibular syndrome
* Neoplasia (e.g. of vestibulocochlear nerve)
* Hypothyroidism
58
Diagnosis of otitis interna
Seek advice from experienced / referral vets
* Establish the presence of systemic and/or localised disease (OE / OM)
* Pruritus, headshaking, pain around the TMJ may be useful indicators of local disease
* Perform complete neurological examination
* Otic examination ± myringotomy
* MRI (possibly CT)
59
Treatment of otitis interna
Seek advice from experienced / referral vets
* In the absence of another cause, long-term use of systemic antibiotics has been advocated
* This may be based on culture of the middle ear
* Ability to cross the BBB
* Consider possible side effects e.g. toxicity
60
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Which antibiotic can cause acute deafness and vestibular syndrome?
Gentamycin
61
Neurological signs consistent with ototoxicity (e.g. in drug reaction)
* Profound hearing loss and vestibular signs
Remember:
* No in-ear reatment is considered otosafe - there is always a risk
* Clinical signs are complicated by competing signs from bacterial toxins / invasion and inflammation
62
What should you do if you suspect an adverse event (e.g. ototoxicity following antimicrobial administration)?
