External and Middle Ear Pathology II Flashcards
Name 5 predisposing factors to ear disease
- Conformation (Stenotic EAM), Excessive hair
- Excessive moisture- swimming, humid climate
- Excessive Cerumen Production
- Treatments (iatrogenic)
- Obstructive Ear Disease- disorders of growth, inflammation
- Systemic diseas- immune supression, debilitation, catabolic states
What is the pathogenesis of otitis externa?
- Extension from the external environment
- Hematogenous spread (cancer cells breaking away)
- Extension from the middle ear
What are the gross features of acute phase Otitis Externa?
- Erythema, Warmth
- Otorrhea = ear discharge/
drainage - Otorrhagia = bleeding from the
ear - Otodynia/ otalgia = ear pain
What are the gross features of chronic phase otitis externa?
- nodular proliferative phase lesions, bosselation
- severe cases have ear canal stenosis
- chronic cases are pinnal haematomas
- inspissated (thickened) debris
What causes an aural haematoma?
- Either head shaking or self-trauma secondary to OE
- haematoma can form intrachondrially or subparachondrially
- often associated with cartilage fractures histologically
What are the clinical signs of parasitical otitis externa?
- Head Shaking
- Repeated Ear Twitching
- Excessive ear itching
- trauma of the auricle and base of ear
What are three examples of parasites that can cause primary otitis externa?
- Notoedres cati
- Otodectes cyanotis
- Psoroptes cuniculi
How does a type I hypersensitivity cause primary otitis externa?
- Reaction to ectoparasites
- Systemic reaction to ingested allergens (food, drugs…)
What is ear margin sebborhea?
type of keratinisation disorder
* waxy crusts cover the ear margin and form small fissures
Give 4 examples of foreign bodies that can cause primary otitis externa
- Plants
- Hair
- Hardened secretions
- Medication
- Sand/ Dirt
Give an example of a glandular disorder that causes primary otitis externa
- Ceruminous gland hyperplasia (masses due to a build-up of ear wax)
Give 4 autoimmune diseases that cause primary otitis externa
- Lupus erythematous
- Pemphigus (folaceous, vulgaris, erythematous)
all cause scaling, crusting (multifocal to coalescing)
What is Vasculitis?
Type III sensitivity
due to a vaccine reaction
What is Myringitis?
Inflammation of the tympanic membrane
What is otitis media?
Inflammation of the tympanic cavity
What are the clinical signs of otitis media?
- Head tilt
- Facial paralysis
- Drooping ears
What is a type I hypersensitivity?
- igE mediated
- causes the release of histamine and other inflammatory mediators
What is type IV hypersensitivity?
Allergic Contact Dermatitis
How does frostbite cause primary otitis externa?
- Decrease in teemperature
- This causes blood to be shunted from the extremities
- Damage of tissue may lead to inflammation
Give an example of an autoimmune disease that causes otitis externa
lupus erythematous
What is the route of infection for otitis media?
- Perforation of the tympanic membrane
- Ascension along the auditory tube
- Extension via degeneration of the temporohyoid joint
- Extension via erosion of the tympanic bulla
- migration along vascular or neural pathways
What are microtia?
Small pinna
common in some species of goat
What species are most predisposed to nasopharyngeal polyps?
Most common in cats under two years old
What is the gross pathology of nasopharyngeal polyps?
pedunculated to polyploid, pale tan mass with smooth surface
What are the clinical signs of otits media?
- Head tilt
- Facial Paralysis
- Drooping ears
- Concurrent respiratory signs
What is type IV hypersensitivity?
- Allergic contact dermatitis
*
What does chronic otitis externa look like?
- Hyperpigmentation
- Lichenification
- pyoderma secondary to pruritis
What dog species is most likely to get primary idiopathic seborrhea?
Dachshunds
What two endocrin disorders cause keratinisation disorders?
- Hypothyroidism
- Hyperadrenocorticism
What lipid related condition also causes keratinisation disorders
epidermal lipid metabolism
What is the effect of frostbite?
- Decrease in ambient temperature
- Blood shunted from extremities
Name three things (not frostbite or vasculitis) that cause vascular disease
- Bacterial sepsis
- Juvenile cellulitis
- Auricular/ Aural chondritis (autoimmune reaction against cartilage)
What respiratory pathogens are often implicated in otitis media?
- Pasteurella multocida, Trueperella, pyogenes, Mycoplasma, Mycoplasma spp. Histophilus somni
What are the clinical signs of otitis media?
- Head tilt
- Facial paralysis
- drooping ears
- concurent respiratory signs
What are the predisposing factors for nasal pharyngeal polyps?
- Upper respiratory infection
- otitis media
What is the predisposing factor for tympanokeratomas?
- Chronic otitis media
What is the gross pathology of a tympanokeratoma?
- Tympanic cavity filled and expanded with pasty yellow to pale-tan material
- loss of normal structures
What is a papillomatosis?
- Flattened, verrucous, well-circumscribed, often depigmented, hyperkeratotic plaques
- associated with equine caballus papillomavirus
- can progress to squamous cell carcinoma
