Otology Flashcards
Ear label (apex, scapha, cutaneous marginal pouch, median/rostral margin, lateral/caudal margin)
T or F: Breed matters more than heat/temp of the ear canal
T
No temp/humidity difference between diseased and normal ears.
T or F: environmental humidity can affect ear canal humidity
F
Do ear canals with or without hair have a higher temperature
Canals WITHOUT hair are hotter
Canals WITH hair are cooler
Which breed has higher ear canal temperatures than other dogs
GSD
Breed with ceruminous gland hyperplasia
Cocker spaniels
Pendulous ears vs hair relationship
Pendulous ears WITH hair get more otitis
(but maybe actually more related to breed)
Erect ears vs hair relationship
Erect ears +/- hairs get less otitis
(but maybe actually more related to breed)
Predisposing, Primary, or Perpetuating: Conformation (hair, anatomic stenosis, pendulous pinnae)
Predisposing
Predisposing, Primary, or Perpetuating: Otodectes cynotis
Primary
Predisposing, Primary, or Perpetuating: excessive moisture (swimming)
Predisposing
Predisposing, Primary, or Perpetuating: trauma from cotton swabs
Predisposing
Predisposing, Primary, or Perpetuating: hair plucking
Predisposing
Predisposing, Primary, or Perpetuating: atopic dermatitis
Primary
Predisposing, Primary, or Perpetuating: bacterial/yeast infection
Perpetuating
Predisposing, Primary, or Perpetuating: otitis media
Perpetuating
Predisposing, Primary, or Perpetuating: Hypothyroidism
Primary
Predisposing, Primary, or Perpetuating: pemphigus foliaceus
Primary
Predisposing, Primary, or Perpetuating: primary idiopathic seborrhea, juvenile cellulitis, sebaceous adenitis
Primary
Definition of predisposing factor
- Facilitate inflammation by permitting alteration of
microenvironment - Establishment of secondary infections
Definition of primary cause
Conditions or disorders that initiate the inflammatory process
What is the most common primary cause of otitis in dogs
Allergic disease
What are the 3 most common causes of otitis in cats
Parasites
Polyps
Allergic disease
What percent of dogs with atopic dermatitis have otitis as their ONLY clinical sign?
10%
What percent of dogs with CAFR have otitis as their ONLY clinical sign?
25%
What is the definition of a perpetuating factor
*Sustain and aggravate the inflammatory process
- Prevent resolution of the otitis externa
*Worsen the otitis externa
Chronic otitis media can lead to ______: a cystic mass near the Eustachian tube
Aural cholesteatoma
Label a pinna (lateral process of antitragus, medial process of antitragus, intertragic incisure, tragis, medial crus helix, tragohelicine incisure, lateral crus helix, anthelix)
*Helix rostrally
*Tragus laterally
*Antitragus caudally
*Anthelix medially
*Intertragic incisure
Routes of infection for otitis media (2)
1) Extension of OE through TM
2) Via eustachian tube
What percent of dogs with chronic recurrent OE develop OM?
89%
(73% still had intact TM! Intact TM does NOT rule out OM)
Which bacteria are most common in canine OM?
-Staphylococcus pseudintermedius
-Pseudomonas aeruginosa
T or F: Malassezia can cause OM
True, in 23.7% of sampled ears in one study!
Breed with PSOM
CKCS
Clinical signs of PSOM
-Head and neck scratching, neurological signs, hearing
loss, otic pruritus, abnormal yawning, head tilt, facial paralysis, or vestibular disturbances
-Intact tympanic membrane, mucoid exudate
Signs of facial nerve paralysis (3)
*Drooping of ear/lip
*Drooling saliva
*Absent palpebral reflex
What eye sign can be related to OM?
Neurogenic
keratoconjunctivitis
sicca (KCS)
Which nerve in the middle ear can cause Dry Nose (xeromycteria)
Parasympathetic
Which nerve in the middle ear can cause Horner’s syndrome
Sympathetic nerve
Signs of Horner’s Syndrome
- Ptosis
-Drooping of upper lid - Miosis
-Contraction of pupil - Enophthalmos
-Backward displacement of
eyeball
into the orbit - Protrusion of nictitating
membrane
Signs of Otitis INTERNA
*Horizontal
nystagmus
*Head tilt, falling, rolling
to affected side
*Asymmetric ataxia
*Hearing loss
Where do you put your cone for otoscopic exam within pinnal structures?
Intertragic incisure
What is the relationship between BW and length of ear canal
Linear relationship exists between BW and ear canal volume
(more drops in larger dogs)
Where are there more hairs: Proximal or distal ear canal
Proximal
Decrease in number
from distal to proximal
What type of gland are ceruminous glands
-Modified apocrine glands
-Located in the deeper dermis
below the sebaceous glands
-Ducts open into either the hair
follicle or onto the surface of
the external ear canal
Who has a faster epithelial migration: the Pars tensa or Pars flaccida?
Pars flaccida!
-Pars tensa = 96.4 μm/d; Pars flaccida = 225.4 μm/d
Is epithelial migration mostly radial or centrigual
Radial
What does the TM look like on histopath? Layers?
– Outer and inner epithelium
– Core of collagen
– Hairless, glandless
Label
Chorda tympani, right ear, dog. The chorda tympani ( arrow ) courses dorsally across the neck of the malleus ventral to the muscular process of the malleus (Mp), in close proximity to the pars tensa. The stapes (S) is anchored in the oval or vestibular window and the foot plate ( arrowhead ) is clearly visible in the opened vestibule (V). The stapes and incus (I) articulate to form the incudostapedius joint.
Ways feline middle ear is different from dog:
*Divided by a septum into 2 separate tympanic
cavities; connected through a foramen between
septum and petrous bone
*Dorsolateral (pars tympanica)
–Auditory ossicles, ostium of auditory tube, tympanic
membrane
–Smaller of the two
*Ventromedial (pars endotympanica)
–Air-filled tympanic bulla
Label middle ear, part of inner ear
Right ear, rostral view, dog. The middle ear has three main compartments. The epitympanic recess ( arrow ) is the smallest, most dorsal compartment occupied by the articulated malleus and incus (I). The next largest is the tympanic cavity proper (Tp) demarcated laterally by the tympanic membrane (torn in this image) and medially by the promontory of the petrous portion of the temporal bone (P). The largest is the ventral compartment (V) surrounded by the bone of the tympanic bulla ( asterisk ). Ventral bony ridge of the external acoustic meatus ( double asterisk ); stapes ( arrowhead ). Bs, brainstem; C, cochlea; Cr, cerebellar cortex; E, external ear canal; F, facial nerve in its facial canal; S, incomplete septum bulla.
Is the oval or round window adjacent to the pars flaccida?
Oval
Does the foot of the stapes touch the oval or round window?
Oval
What is the other name for the oval window
vestibular
What is the other name for the round window
cochlear
What is the eustachian tube
- Extends from
nasopharynx to tympanic
cavity - 8mm long
- 1.5mm diameter
- Equalizes pressure
- Cartilagenous,
junctional, osseous
Where is the ideal myringotomy site?
Ventocaudal
Name of the fluid inside the inner ear
Perilymph
Portion of spiral passage that ascends into cochlea
Scala vestibuli
Portion of spiral passage that exists cochlea
Scala tympani
What is inside the cochlea duct (that runs alongside the scala vestibuli and scala tympanic
endolymph
What sends nerve impulses to the brain due to vibrations from the basilar membrane in the cochlea?
Organ of corti via cochlear nerve
What cells are inside the organ of corti, to induce nerve transduction
Hair cells
T or F: most PSOM cases have bacteria isolated via traditional culture
False
Due to increased production of mucus vs decreased drainage via eustachian tube
Healing time for ruptured TM in ideal conditions
21 to 35 days
Possible complications from deep ear flush
-Facial nerve paralysis
-Horner’s Syndrome
-Vestibular disturbances
-Deafness
Which of these medications are ototoxic?
-Gentamicin
-Chlorhexidine
-Ceruminolytic agents
-Tris-EDTA
-Tobramicin
-Gentamicin
-Chlorhexidine (if >0.2% in dogs, ANY CONCENTRATION IN CATS)
-Ceruminolytic agents
-Tobramicin
Tris-EDTA is SAFE
Tobramycin is V BAD. Can cause both hearing loss AND vestibular signs
What cytology result is the strongest indicator of OE?
Inflammatory cells
Never present in normal ears
Are rods on cytology normal in a canine ear?
No, but cocci can be
For MRI: is T1 or T2 better for distinguishing fluid in bulla
T2: fluid shows up hyperintense
(isointense on T1)
Brachycephalic bulla on MRI
Brachycephalics have smaller bullae, so the bulla wall can look thicker on MRI
Why is Cerumene for in-clinic use only?
Urea or carbamide peroxide ceruminolytics need to be flushed out
T or F: 64% brachycephalics had OM on CT; many with OM also had changes to soft palate thickness
T
MOA of ceruminolytics
Hydrate desquamated sheets of corneocytes, inducing keratolysis and disintegration of cerumen
MOA of surfactants
Decrease surface tension between water and lipids or organic solids to break up and help remove debris
MOA of lubricants
Softening effect
Which organism is Malacetic proven effective against?
Yeast
Effect of topical glucocorticoids on sebaceous and apocrine glands
Decrease sebaceous and apocrine secretions
Effect of topical glucocorticoids on adrenal glands
Can occasionally cause adrenal suppression
Which 2 medications are most likely to cause a topical reaction
Neomycin
Propylene glycol
(no source for this, but from Lynette Cole lecture)
Which bacteria is Polymixin B ineffective against?
Proteus
What inactivates polymixin B
Purulent debris
What can be combined with polymixin B for a synergistic effect against Pseudomonas and Malassezia
Miconazole
Which bacteria is florfenicol ineffective against
Pseudomonas
Which bacteria (3) is fluoroquinolones ineffective against
Streptococcus, Enterococcus, Anaerobes
Are gram positive or gram negative bacteria more susceptible to Tris-EDTA
Gram negative
MOA of Tris-EDTA
*Leakage of cellular
components,
permeability of
antibiotics
*Tromethamine
enhances the effect of
EDTA
Mechanism for permanent deafness or balance issues
Loss of hair cells in inner ear
Medications with highest risk of ototoxicity, usually permanent
Aminoglycosides (gentamicin, amikacin)
Cisplatin
Which heart medication can be ototoxic?
Furosemide (loop diuretic)
Usually temporary
With ototoxicity, is hearing loss first a high or low frequencies?
High frequencies are lost first
2 non-drug causes of hearing loss
Noise, age
Other than aminoglycosides, which other antibiotics have been associated with ototoxicity
Erythromycin
Which antipyretic has been associated with temporary hearing loss
Salicylates
Can SQ aminoglycosides still induce ototoxicity?
Yes
Does gentamicin target balance, hearing, or both
Both
Does amikacin target balance, hearing, or both
Hearing only
T or F: aminoglycosides can cross the placental barrier and cause deafness in fetuses
T
MOA of ototoxicity by aminoglycosides
Oxidative stress caused by the overproduction of reactive oxygen species (ROS)
How can you prevent ototoxicity in animals
Give a concurrent antioxidant with your drugs (ie aspirin, but never in cats. ie silymarin, vitamin E)
MOA of furosemide temporary ototoxicity
Increase in the sodium concentration and a reduction in potassium activity in the endolymph.
Relationship between brachycephalics and otitis media w/effusion (OME) on MRI
CKCS w/ bilateral OME had a significantly greater thickness of the soft palate and reduced area of the nasopharynx compared with CKCS without OME.
Most common aural tumors in dogs
*Ceruminous gland adenoma/carcinoma
*Papilloma
*Histiocytoma
Most common aural tumors in cats
*Ceruminous gland adenoma/CA
*SCC of the pinna
*Inflammatory polyps of the middle ear
Which is the germinal center of the TM
Umbo
Where do polyps arise from in cats
mucosal lining of the middle ear, the auditory tube, or the nasopharynx
Etiology of polyps in cats
Chronic inflammation of the middle ear mucosa from a:
-viral-mediated otitis media
-chronic stimulation
-ascending bacterial infection
Feline polyp histopath findings
-Vascularized fibrous connective tissue
-Stratified squamous or columnar epithelium
-Lymph, plasma cells, macrophages
present
Canine polyp histopath findings
-Keratinizing squamous epithelium
-Hair follicles, sebaceous, ceruminous glands present usually, but some lacked adnexa.
-SOME have cuboidal to ciliated columnar epithelium
Treatment options for aural inflammatory polyps (3+1)
1) Trans-tympanic traction-avulsion
2) Traction-avulsion with rostral soft palate retraction
3) Ventral bulla osteotomy
4) Normograde rigid rhinoscopy-assisted traction-avulsion
Recurrent ear mite infection in cats can predispose them to _____
Ceruminous gland adenocarcinoma
Breed predisposed to leproid granuloma
Boxer
Organism implicated in canine leproid granuloma; location on body
Saprophytic Mycobacteria, base of ears (anywhere on head, distal limbs. No LN involvement)
Is hot or cold more associated with development of leproid granulomas
Cool; why they prefer ears. More common in cooler months.
Spread by inoculation from bug bites vs trauma
Diagnosis of leproid granuloma
Acid fast + on FNA or histopath
Macrophages contained many small, non-staining (clear) linear structures, consistent with Mycobacterium sp.
Treatment leproid granuloma
Spontaneous resolution is reported, but usually sx or long term antibiotics (rifampin, clarithromycin) needed
Organisms that can cause infectious cutaneous granulomas (9) on the pinna
Leishmania sandflies bite the ears and face
-Blastomyces dermatitidis
-Crytococcus
-Histoplasma capsulatum
-Neospora caninum
-Toxoplasma gondii
-Trypanosoma cruzi
-Sporothrix schenchkii
-Other opportunistic fungal infx
What should you evaluate for in a pet with a para-auricular abscess
Usually 2’ obstructive hyperplastic proliferative OE
Can be due to neoplasia, OM, TECA, trauma –> always check for cancer
Origin of most aural polyps in dogs
Ear canal
Origin of most aural polyps in cats
Tympanic bulla, eustachian tube
Virus associated with aural polyps in cats
Calicivirus
Of cats that required TECA for end stage ear 2’ chronic OE, which histopathologic feature was present 100%
Ceruminous gland hyperplasia
T or F sebaceous gland hyperplasia is 2’ chronic inflammation
False
Pinna in a 3 month old cat. Diagnosis
Proliferative and Necrotizing Otitis Externa (of Kittens)
Cell involved in Proliferative and Necrotizing Otitis Externa (of Kittens)
CD3+ T cells
Treatment for Proliferative and Necrotizing Otitis Externa (of Kittens)
Tacrolimus (works in 2 weeks)
T or F: Proliferative and Necrotizing Otitis Externa (of Kittens) is triggered by viruses
False.
At least, not yet found
Mass occurring in the middle ear (pearly white mass); etiology = 2’ invagination of stratified squamous epithelium from the external ear canal.
Aural keratinizing cyst (cholesteatoma)
Nonneoplastic mass in the bulla commonly associated with boney changes on CT (osteoproliferation, osteolysis)
Aural keratinizing cyst (cholesteatoma)
Feline ceruminous cystomatosis sex predilection
Males
Inflammatory mass in the middle ear of dogs with chronic OM. Cholesterol aggregates seen on histopath
Cholesterol graunloma
Yellow, round to irregular, variably friable mass
Feline ceruminous cystomatosis breeds
Abyssinian, Persian
Causes of noninfectious granulomatous lesions in dogs (4)
1) Sterile granuloma and pyogranuloma syndrome
2) Cutaneous xanthoma
3) Canine sarcoidosis
4) Foreign body reaction
Diagnosis??
7 yo FS dog with nonpruritic, nonpainful papules, plaques, and nodules on trunk, neck, face, and ears. Responsive to steroids, cyclosporine
Histopath: multifocal nodular inflammation composed of pale, slightly vacuolated epithelioid histiocytes with giant cells and a few lymphocytes in the superficial-to-deep dermis. Gram/acid fast/GMS stains = negative.
Epitheliod cells = + for CD18 and Iba1 (macrophage)
canine sarcoidosis
Which organisms do you need to rule out in “Sterile granuloma and pyogranuloma syndrome” that are difficult to culture
Mycobacterium
Leishmania
Disease in cats > dogs 2’ to dyslipoproteinemia. Results in a bilaterally symmetric, preauricular multi-
focal to coalescing, white-yellow plaques or nodules
Cutaneous xanthoma
Species with Auricular chondritis/chondrosis
Cats (1 dog)
T or F: areas other than the pinna are also often affected with Auricular chondritis/chondrosis
False
Clinical signs Auricular chondritis/chondrosis
Markedly swollen, curled, and painful pinna with intense erythema.
Unilateral progresses to bilateral
Treatment Auricular chondritis/chondrosis
Immunosuppression +/- pinnectomy
Idiopathic benign lichenoid keratosis: clinical signs, treatment
hyperkeratotic plaque or papules on concave pinna
Sx = curative
Body sites affected by Canine cutaneous histiocytomas
Head, pinnae
Type of cell in Canine cutaneous histiocytomas
Langerhan cell
IHC for _____ confirms langerhan cell origin in canine cutaneous histiocytoma
E-cadherin
Plasmacytoma location on body
Feet, lips, and ear canal
Are aural neoplasms more likely to be benign or malignant
Malignant
Cats (85%)
Dogs (60%)
Though rare, what is the most common MIDDLE ear neoplasm in dogs and cats
SCC
SCC on a pinnal tip and preauricular area. What signalment is most likely
White cat
2 predisposing factors for SCC in external ear canal
1) Damaged skin
2) Continuous exposure to cerumen (potentially carcinogenic?)
Most common location of cutaneous hemangiosarcoma in cats
Pinnae (>50%)
Likely UV associated in light colored cats
Body location of feline sarcoids (feline cutaneous fibropapilloma)
head (nares, lips, and pinnae)
Virus implicated in feline sarcoids (feline cutaneous fibropapilloma)
BPV-14
Signalment of animal with feline sarcoids (feline cutaneous fibropapilloma)
Rural, young male cat
Fighting behavior?
Treatment feline sarcoids (feline cutaneous fibropapilloma)
Surgery. Locally infiltrative, so concern for local recurrence
Muscles responsible for the mobility of the pinna
Rostroauricular and ventroauricular muscles
Breed with more excessive compound hair follicles within horizontal ear canal
Cocker spaniel
Content of cerumen
Desquamated cornocytes, apocrine secretions, and sebaceous secretions
Where does epithelial migration start? Where does it go?
Starts at manubrium of malleus (germinal center)– spreads laterally, radially
Most common bacteria in dogs with acute OE
Staphylococcus and Bacillus sp., yeast, and less frequent Streptococci, E.coli, Corynebacterium sp. and Micrococcus
species
Pseudomonas sp. and Proteus sp. are rarely cultured.
Most common bacteria in dogs with chronic OE
Staphylococcus pseudintermedius, Pseudomonas aeruginosa, E.coli, beta hemolytic streptococcus, Proteus sp., Enterococcus sp., Corynebacterium sp.
Name for structure where tympanum attaches to surrounding bone
Annulus fibrocartilagenous
