Ear Questions Flashcards
- Which area of the ear canal has more glands and follicles in the dog?
a. Vertical canal
- What is the process of natural migration in the epidermis and tympanum of the canine ear canal?
a. Mainly in out pattern with some centrifugal epithelial migration across the tympanum and up the ear canal to the surface
- What cranial nerves travel through the tympanic bulla and may be disrupted during a myringotomy?
a. CN VII (Facial) and CN IX (Glossopharyngeal)
- What is the function of the Eustachian tube? (3 functions)
a. Equalize air pressure between the middle ear and nasopharynx
b. Protect middle near from nasopharyngeal pathogens
c. Ventilation and drainage of the middle ear
- Describe the common clinical signs of PSOM in dogs.
a. Moderate to severe pain around the head/neck with or without neurologic abnormalities
b. Viscous, non-infected mucus plug in the middle ear, accompanied by a bulging tympanic membrane (not always, but common)
- Describe this CT image and give 3 differentials for the condition.
Answer:
a. Right-sided fluid attenuation and mildly enhancing soft tissue in the bulla, extending to the horizontal ear canal with multifocal lysis of the right bulla
b. Differentials: abscess is primary concern, rule out cholesteatoma and neoplasia with secondary infection
- Be able to label the following parts of the ear canal.
Answers: a = pinna, b = vertical canal, c = horizontal canal, d = facial nerve, e = external ear,
f = middle ear, g = Eustachian tube, h = tympanic bulla, i = otic nerve, j = auditory ossicles,
k = tympanic membrane
- Be able to label this image. What species is that?
Answers:
- This is a cat (malleus is much straighter in cats)
- Included items to label:
o Malleus (bony hook)
o Pars tensa (majority of visible ear drum)
o Pars flaccida (small dorsal portion)
- Be able to label this image.
Answers: 1 = pars flaccida, 2 = pars tensa, 3 = manubrium of the malleus
- Where do squamous cell carcinomas occur on in cat and dog ears?
a. Dorsal ear tips and lightly haired preauricular areas most commonly
- At what angle is the tympanic membrane oriented and where it is attached in the dog and cat?
a. 30 – 45 degree angle
b. Attached to medial aspect of external acoustic meatus
- What portion of the ear drum should be punctured during a myringotomy?
a. Posteroventral quadrant, below the manubrium attachment in the pars tensa
- What are the three types of cleaning agents used for the ear?
a. Ceruminolytics
b. Mild cleansers
c. Antiseptics and drying agents
- Define primary, secondary, predisposing, and perpetuating causes in dogs and cats with otitis.
a. Primary = creates disease in the normal ear
b. Secondary = creates disease in the abnormal ear
c. Predisposing = increase risk for development of otitis externa
d. Perpetuating = inflammation of the ear canal and middle ear interferes with resolution of otitis to promote more secondary infections
- Describe these biopsy findings and give potential differential for mass removed from a dog’s ear canal.
Answer:
a. Squamous epithelium partially surrounding a cystic structure with abundant lamellar eosinophilic keratin debris
b. Possible etiology = cholesteatoma
- Which of the following classifications of ear disease creates ear disease in a normal ear? (multiple choice)
a. Primary factors
b. Secondary factors
c. Perpetuating factors
d. Predisposing factors
a. Primary factors
- List 3 – 5 primary, secondary, predisposing, and perpetuating causes of otitis in dogs and cats.
a. Primary:
i. Allergy (contact, atopy, food allergy)
ii. Autoimmine = Pemphigus foliaceus, bullous pemphigoid, erythema multiforme
iii. Endocrine = Cushings disease, hypothyroidism
iv. Epithelialization disorders = Primary idiopathic seborrhea, zinc responsive dermatosis
v. Foreign bodies
vi. Dermatophytosis
vii. Parasites (Demodex, Otodectes cynotis, Otobius megnini)
b. Secondary:
i. Bacterial infection (Staph, Strep, Enterococcus, Pseudomonas, Proteus, E. coli, Corynebacterium)
ii. Aspergillus or Penicillium fungal species
iii. Topical irritant reactions
iv. Overcleaning
v. Malassezia pachydermatis infection
c. Predisposing:
i. Conformation = Excessive hair growth, pendulous pinnae, stenotic canals
ii. Excessive moisture from swimming or over-bathing
iii. Neoplasms
iv. Ceruminous cystomatosis
v. Feline inflammatory polyps
vi. Primary secretory otitis media (PSOM)
d. Perpetuating:
i. Excessive debris production and altered migration of epithelium
ii. Ear canal lichenification
iii. Thickened tympanic membrane or healing with a permanent hole
iv. Calcification due to chronic disease
v. Gland blockage or dilation
vi. Cholesteastomas
vii. Otitis media
- Describe characteristics that differentiate cholesteatomas from middle ear neoplasia and chronic otitis media/externa on CT.
a. CT will show contrast enhancement of tissue directly adjacent to the bone in cholesteatomas, but neoplasias extending into the middle ear will contrast enhance more widely
b. Chronic otitis media/externa will not expand the bulla, unlike cholesteatomas
- Describe the clinical signs and location of ceruminous cystomatosis in cats.
a. Location = concave pinna, external orifice, ear canal
b. Clinical signs = multiple coalescing papules/vesicles/nodules/plaques that are blue-brown-black and express yellow fluid when punctured
c. Secondary otitis externa can occur
- What are the suspected causes of primary secretory otitis media in dogs?
a. Increased mucus production in the middle ear
b. Decreased middle ear drainage through the auditory tube
- What frequencies are most affected in hearing loss by older dogs, and what histological findings correlate with this change? (2 changes)
a. 6 – 12 kHz
b. Geriatric dog cochlea changes:
i. Reduce outer and inner hair cell counts
ii. Reduced spiral ganglion packing density
iii. Reduced stria vascularis cross sectional area
- How do Pseudomonas species form biofilms and what are biofilms made of?
a. Secrete exopolysaccharides, such as alginate, which attach to surfaces and block bacterial removal and phagocytosis by white blood cells
- What structure is this biopsy of?
a. Ear cartilage sample
- What is the most common effective treatment of PSOM in dogs? What is its prognosis for cure?
a. Myringotomy with flushing of the middle ear – will need to be repeated in the future, cure is unlikely
- What is the tissue of origin of feline inflammatory polyps?
a. Epithelial lining of tympanic bulla and auditory tube
- What parasite can cause otitis in cats specific to the northwest pacific? How is it diagnosed?
a. Mammomonogamous auris
b. Can see swimming behind the ear drum on otoscopic exam
- What condition can also be present in dogs with Primary Secretory Otitis Media?
a. Caudal Occipital Malformation
- A patient presents with a history of chronic unilateral otitis externa. On otoscopy, polypoid masses are noted along the canal. Biopsy of these masses yields eosinophilic granuloma or dermatitis, intraepidermal eosinophilic microabscesses, and areas of degenerate collagen. What is the likely diagnosis in this case and what is treatment?
a. Canine proliferative eosinophilic otitis externa
b. Treatment = surgical excision is curative or may show recurrence in future
- What are four theories of the etiology of aural cholesteatomas?
a. Primary Acquired = Eustachian tube dysfunction causes invagination of TM into bulla
b. Secondary Metaplasia Acquired = chronic inflammation causes transformation of ciliated respiratory epithelium into stratified squamous epithelium in bulla
c. Secondary Migration Acquired = Break in TM allows stratified squamous epithelium to enter the bulla
d. Secondary Invasion Acquired = Break in basement membrane allows TM keratinizing epithelial cells into the subepithelial space
- Name 4 - 5 common techniques for treating aural hematomas.
a. Curvilinear incision and flushing with sutures
b. Closed suction drainage
c. Placement of cannula for intermittent drainage
d. CO2 laser with partial and full thickness circular incisions
e. Daily needle drainage
- What are the clinical signs of feline and canine inflammatory aural polyps? How do they differ?
a. Canine = otorrhea (fluid drainage from the ear), ear scratching, head shaking, otitis
b. Feline = otitis externa, neurologic signs (Horner’s, head tilt, ataxia, facial paralysis)
- What is the mechanism of furosemide ototoxicity? (2 ways)
a. Causes concentration of other ototoxins in cochlear endolymph (cisplatin, aminoglycosides) and blocks active potassium transport in stria vascularis
b. Decreases endocochlear potential, reduces amplitude of vestibulocochlear nerve action potential, causes edema and degeneration of stria vascularis
c. Causes reversible, auditory ototoxicity
- What is the difference in origin of aural/nasopharyngeal polyps and nasal hamartomas in cats?
a. Aural/Nasopharyngeal polyps originate from the lining of the tympanic bulla or auditory tube
b. Nasal hamartomas originate from the nasal cavity tissue
- A male cat < 4 years old presents with signs of bilaterally symmetric, tightly adhered crusts with erythematous plaques and ulcers on the concave pinnae only. Give three differentials for this condition.
a. Pemphigus foliaceus, feline proliferative necrotizing otitis externa, Otodectes cynotis infestation
- Describe 5 predisposing and primary factors involved in external ear canal lesions in alpacas.
a. Ectoparasites, foreign bodies, pruritic/painful diseases (lacerations, frostbite, dermatophytosis, dermatophilosis)
- What is the presumed etiology of feline proliferative and necrotizing otitis externa?
a. T cell induced caspase-positive epidermal keratinocyte apoptosis, similar to erythema multiforme (external pathway of apoptosis)
- What are the recommended treatments for ceruminous cystomasosis in cats?
a. Laser therapy (best option)
b. Vertical canal resection or TECA may be needed in cases of recurrent otitis and failure to control with medications
- Describe the clinical appearance of ceruminous gland adenomas versus adenocarcinomas? What is their behavior?
a. Adenoma = small, multiple, pedunculated and pigmented masses that are variably irregular and firm
b. Adenocarcinoma = irregular, raised to plaque-like, variable ulcerated and locally invasive tumors
c. Behavior of malignant form = 50% metastasize to regional lymph nodes, lungs, and viscera
- True/False – Juvenile cellulitis can start with otitis externa and pinnal disease.
a. True
- Describe this finding on CT scan in a dog.
Answer:
a. Left tympanic bulla is enlarged with soft tissue material, bony lysis and osteoproliferation of the bulla wall with cochlear lysis
b. Suspect cholesteatoma due to lack of widespread contrast enhancement
- True/False – Pseudomonas bacteria tend to be susceptible to beta lactam antibiotics.
a. False – most are resistant via porins and efflux pumps in the cell walls along with beta lactamase enzymes
- What are feline hamartomas?
a. Inflammatory, expansile polyps of the nasal turbinates
- Rod-shaped bacteria are found on cytology of a dog’s ear. What are four likely differentials for the species of bacteria that were found?
a. Pseudomonas aeruginosa
b. Corynebacterium spp.
c. E. coli
d. Proteus mirabilis
- A 10 year old cat presents with a history of otitis externa that is recurrent. On physical examination, the following is seen. What is the diagnosis of this condition and what are the expected biopsy findings upon removal?
Answer = ceruminous cystomatosis of cats
Biopsy findings = ceruminous gland cystic hyperplasia – stratified squamous epithelium lined with multiple cysts, filled with inspissated material or clear liquid
- What is the etiology of canine leproid granulomas?
a. Infection by saprophytic mycobacterium transmitted by biting insects or traumatic inoculation
- In what breed of cat do inflammatory polyps appear to be congenital?
a. Maine Coons
- Be able to describe the pros and cons of TECA, bulla osteotomy, lateral resection and vertical ear canal resections in animals.
- Where on the tympanum should the myringotomy be performed (1, 2, 3)?
Answer: 2 (pars tensa – rostroventral portion)
- Describe these MRI findings in a dog.
a. Expansile left bulla containing material isointense to brain tissue (left side) or heterogenous hyperintense to brain tissue (right)
- Describe the findings in these four CT images of a bulla
top left = normal tympanic bulla
top right = fluid-filled tympanic bulla and normal wall
bottom left = fluid filled tympanic bulla with thickened, irregular wall
bottom right = lysis of wall with fluid-filled tympanic bulla
- Label the portions of the equine ear canal.
Answer:
a. CN V
b. Cerebellum
c. Guttural pouch
d. Tympanic membrane
e. Occipital bone
f. External ear canal
g. Spiral canal
h. Petrous temporal bone
j. Tympanic bulla
k. Basisphenoid bone
- Describe the following MRI findings.
a. Left facial nerve is thickened and hyperintense to grey matter with mixed signal density in the left tympanic bulla
See the image of an ear with the TM removed (looking down the left external canal into the middle ear). Label the parts of the middle ear.
