Dermatology: Otitis Flashcards
(42 cards)
How does tympanic bulla vary between cats and dogs?
How does the epithelium of ear canal and middle ear vary?
Ear canal
* Small hairs
* Ceruminous glands
* Sebaceous glands
Middle ear
* Simple squamous to cuboidal
* Few ciliated cells
* Mucous-secreting goblet cells
How does the external ear canal self clean?
Cerumen
* Sebaceous and ceruminous gland secretions
* Catches foreign material, desquamates keratinocytes and microbes
* Contains antimicrobial peptides and Igs
Epithelial migration
* Living keratinocytes carry cerumen and contents out of canal
How does the middle ear self clean?
- Mucous from goblet cells traps microbes and cellular debris
- Eustachian tube- drains mucous from middle ear cavity inot nasopharnx, equalises pressure either side of tympanic membrane
What is the normal flora in the EEC?
Gram +ve predominate
* Staph pseudintermeidus, schleferi
Coagulase -ve staphylococci
Streptococcus
Micrococcus
Malassezia
What is otitis externa, media and interna?
Inflammation of the
externa: EEC
media- middle ear
interna- inner ear
What can cause pruritic and non pruritic disease of the pinnal margin, skin surface and body of the pinna?
Pinnal margin
* Pruritic- sarcoptic mange, harvest mites
* Vascilitis, seborrhoea, SCC
Skin surface
* Pruritic- allergic skin disease, pemiphiguc foliaceus, contact irritant dermatitis, fleas
* Non-pruritic- hyperadrenocorticism, hypothyroidism, pemiphiguc foliaceous, contact irritant dermatitis
Body
* pruritic- aural haematoma
* non-pruritic- auricular chondiritis
What is the acronym for primary causes of otitis?
VIP MEGA FAME
What are the most common primary causes of otitis in dogs?
Foreign bodies
Allergic skin disease
Bugs- parasites/virus
What are the most common primary causes of otitis in cats?
FAB
Flu
Allergic skin disease
Bugs
What parasite is the most common cause of otitis?
Otodectes cynotis
- Dark coffee ground wax, small white mites
- Most patients have HSR to mites
How is otodected cynotis treated?
- Most oily topical ear products effective
- Selamectin or moxidectin spot on
- May need steroids for prutritis and inflammation
What are secondary causes of otitis?
Microbial infection-
* gram +ve cocci
* gram -ve rods- pseudomonas
Topical medication reaction
Inappropriate cleaning- physical trauma, excessive moisture
What predisposes of otitis?
- Obstructive ear disease- neoplasia and polyps
- Conformation- hairy canals, narrow cannals, waxy canals, pendulous pinnae
- Environment- water, high temp
- Systemic disease- immune suppression, debilitation
What are prepetuating factors for otitis?
Progressive pathological change
* chronic inflammation of soft and bony tissues due to primary and secondary causes
Otitis media
Describe progressive pathological change from otitis?
- Failure of epithelial migration
- Progressive epithelial hyperplasia, oedema, fibrosis and folding
- Glandular dilation and hyperplasia
- Canal stenosis
- Rupture of tympanum
- Calcification of pericartilgenous tissue
- Osteomyeltitis
- Para-aural abscessation
What are the clinical signs of OE?
- Otic pruritus- scratching, rubbing, headshaking
- Pain
- Discharge
- Loss of hearing
- Secondary- erythema, lichenification, scaling
- Otoscopy- epithelial erythema, hyperplasia, erosion/ulceration, fibrosis, stenosis of EEC
How does otitis externa progress?
Secondary causes and perpetuating factors follow
* Malassezia overgrowth
* Changes in EEC environment- inflammatory change
* Gram -ve rod infection
* Chronic pseudomonas progress to OM in dogs
What are the clinical signs of OM and OI?
- OE signs
- Pain
- Horners
- Loss of hearing
- Vestibular disease- ataxia ± falling, head tilt, spontaneous/rotary nystagmus, anorexia/vomiting
What causes primary otitis media?
Dogs
* haematogenous spread
* breed related conformation abnormality
Cats
* nasopharyngeal polyps
What is primary secretory otitis media?
- CKCS and other brachycepahlics
- Mucus build up
- Present for deafness or pain
- Bulging TM on otosopy
- Repeated flushing with sterile water eventually liberates large mucus plug
What is brain auditory evoked response?
Used to ID hearing loss
* Noise applied to test ear generates neuronal activity
* Can ID site of pathology at different peaks
What is the dignostic plan for otitis of canines?
Primary causes
* elimination diet and rechallenge when otitis resolved
Secondary causes
* cytology
Predisposing factors
* Drying anf cleaning of ears post swiming
Perpetuating factors
* Otoscopy under sedation/GA to assess EEC and TM
* DI to investigate OM
What is the diagnostic plan of feline otitis?
Primary causes
* viral testing?
Secondary causes
* cytology
Predisposing factors
* Diagnotics imaging to investigate poly, biopsy
Perpetuating factors- investivated OM
