LEC 9 - Ears Flashcards
What are the commensal bacteria found in the external ear?
Bacillus
Corynebacterium
E. Coli
Strep/Staph
Malassezia
What is the mucocillary apparatus?
Combination of goblet cells and ciliated columnar epithelail cells
Found in middle ear
What is the acoustic reflex?
Contraction of the tensor tympani + stepdius muscle in response loud/injurious noise
Term: Auricular agenesis
Defect at embryological development
No ears
What are two causes of atresia of external acoustic meatus?
Congenital
– or –
Trauma
Term: Altricial
Animals that are helpless at birth
Puppies + Kittens
Term: Precocial
Active shortly after birth
Meatus open at birth
In what animals is auricular hypoplasia normal?
La Mancha goat breed
– and –
Scottish fold cats
What are the primary causes of otitis externa?
Ectoparasites
Keratinization defects
Foreign bodies
Hypersensitivity reactions
Systemic immune mediated disorders
What are the most common primary causes of otitis externa in dogs?
Atopic dermatitis
Adverese food reactions
Ectoparasites
Foreign bodies
What are the gross findings with otitis externa?
Exberant discharge
Hemorrhage
Skin that is red, warm, and edematous
Hyperpigmentation in chronic cases
What are the histological findings with otitis externa?
Edema
Influx of inflammatory cells
Hyperplasia of epidermia
Hyperkeratosis/crusts +/- fibrosis
What is the common cause of infarcation of the external ear in pigs?
Septicemic Salmonaellosis
What is the common cause of infarcation of the external ear in cats?
FIP
What is the common cause of infarcation of the external ear in dogs?
German Shephard
w/ familial vasculopathy
What types of toxins can lead to infarction of the outter ear?
Cause vasoconstriction + vascular compromise
Ie. Alkaloids
What is the gross description for an aural hematoma?
Swollen
Warm
Hyperemic
Heavy ears that tend to drop
What occurs with in frostbite along with the infarction?
Dry gangrene
What is contained within an ear that has an aural hematoma?
Blood and fibrin
Strands of eosinophilic fibrin strands
What are the four main ear mite types?
Otodectes cyanotis
Notoedres cati
Raillietina ssp.
Psoroptes cuniculi
What animals does otodectes cyanotis tend to infect?
Wild cats
Dogs
Occasionally ruminants
What do otodectes cyantosis do?
Non-burrowing
Feed on cermimen + keratin + lipids
What is grossly present with otodectes cyanotis?
A lot of cerumen production
Dark brown waxy material that obstructs ear canal
Auricles can be alopecic + scratch wounds
What animal does notoedres cati tend to infect?
Cat
but also dogs, foxes, and rabbits
Where is Notoedres Cati resticted to on the body?
Head + Face + Neck + Shoulders
How does notoedres cati infect the host?
Burrows into the stratum corneum
What is grossly apparent when notoedres is present?
Alopecic
Thick crusting
Excoriation of rostral pinna
What animals does raillietina species tend to infect?
Cattle + Buffalo + Goats
How do Raillietina tend to infect their host?
resides deep in external acoustic meatus
Just next to tympanic membrane
What is grossly seen with a raillietina ssp.?
Thick plug of cerumen + debris
Where does psoroptes cuniculi tend to live on the body?
Skin
What animals does Psoroptes Cuniculi tend to infecT?
Sheep
Goat
Deer
Horses
Donkeys
Mules
Antelopes
What are the two important tick speices?
Rhipicephalus spp.
– and –
Gulf coast ear tick
What breed of cattle does rhipicephalus tend to infect?
Bos tarus
How does rhipicephalus cause there to be “cement” in the external auricle?
Secrete proteins in their saliva
Reacts with host enzymes
= hard feeding cone
What animals does the gulf coast ear tick most commonly infest?
Cattle
Sheep
Horse
What is the gulf coast tick a vector for?
Cowdria ruminatium
What disease does Cowdria ruminatium cause?
Heartwater disease
What is the causative agent for dermatophiosis?
Dermatophilus congolensis
What is important to remember when dealing with dermatophilus congolensis?
It is Zoonotic
What parts of the body does dermatophilus congolensis infect?
Skin/Mucosa of the Nose
Commissures of the Lips
Distal/Proximal limbs/ears
How is dermatophilius conogolensis transmitted?
Dam to feeding offspring
How does colonization of dermatophilus occur?
Flagellated zoospores penetrate the epidermis
Reach basement membrane
Transform into filamentous morphology
What causes the crusty appearance of an animal infected with dermatophilus congolensis?
Cycle of bacterial growth + inflammation + epidermal regeneration
= Multilaminated pustular crust
What is the gross description of the lesion caused by dermatophilus congolensis?
Crusting + Exudative dermatitis
What are the most common neoplasms in the ear of a dog?
Sebaceous gland tumor
Histiocytomas
Plasmacytomas
Mast cell tumors
What are the most common neoplasms of the cats ear?
Basal cell tumors
Vascular tumors
Squamous cell carcinomas
What two common neoplasms of the ear are seen in both dogs and cats?
Ceruminous gland adenomas
– and –
Adenocarcinomas
What is the appearance of adenomas in the ear?
multiple + small + pendunculated irregular firm masses
What is the gross appearance of adenocarcinomas?
Locally invasice and expansile with tendency metastasize
What animal are adenocarcinomas most commonly seen?
Old, male cats
Where do adenocarcinomas tend to metastizise to?
Regional lymph nodes
Lungs
Systemic viscera
What kind of disease is pinnal alopecia in cattle? What type of cattle?
Congenital disease
Polled hereford breed
What type of disease is pinnal alopecia in cats/dogs? What breeds are affected?
Acquired
Dogs: Dachshunds
Cats: Siamese
What is the histological appearance of ceruminous gland adenocarcinoma?
Haphazardly arranged + formed tubules/acini
Evidence of anaplastic/mitotically active cells
Who does primary ciliary dyskinesia tend to affect?
Dogs
< 1 years of age
What clincal symptoms are seen in dogs with primary ciliary dyskinesia?
Persistant cough
Nasal discharge
With a history of recurrent respiratory disease
What are the three possible reasons for primary ciliary dyskinesia to occur in dogs?
Dynein arm deficiency
Abnormal microtubular patterns
Random orientation of microtubules
What is seen grossly with primary ciliary dyskinesia?
Mucopurulent exudate
– or –
Sterile gelatinous material
Filling the tympanic cavity
What are the causative agents for otitis media in pigs?
Pasturella multocida
trueperella pyogenes
Mycoplasma hyorhinis
What are the causative agents in cows with otitis media?
Pasurella multocida
trueperella pyogenes
Mycoplasma bovis
Histophilus somni
Streptococcus
What is otitis media commonly a result of?
Nasopharyngeal ascending infections
What is seen grossly in animals with otitis media?
Unilateral/bilateral
Bulla filled with fibrinopurulent to caseous exudate
What can be seen grossly in chronic cases of otitis media?
Mucosa becomes thickened
Stenotic due to fibrosis
What is the causative agents for otitis media in cats?
E. Coli
Enterobacter/Enterococcus
Strep/Staph
Proteus
Clostridium
What is seen grossly in a cat with otitis media?
Bulla filled with fluid
What are the predisposing factors for cats to develope nasopharyngeal polyps?
Chronic infections
Otitis media
Ascending middle ear infections
Congenital defects
What is the clinical presentation of a cat with a nasopharyngeal polyp?
Nasal, otic, or ocular discharge
Sneezing
Dyspnea
Stridor
Voice change
Head tilt
What can be seen clinically with cats that have severe nasopharyngeal polyps?
Cyanosis
– and –
Syncope
What is seen grossly in cats with nasopharyngeal polyps?
Pedunculated to polypoid growths
Smooth surface
Protrude through auditory tube into nasopharynx
What type of mass is nasopharyngeal polyps?
Non-neoplastic
Inflammatory
What is seen in histology of a nasopharyngeal polyp?
Fibrovascular core
with:
Lymphocytes
Plasma cells
Macrophages
Covered by epithelium
What can otitis interna result in?
meningitis
Ventriculitis
Encephalitis
What causes vestibular disease?
Injury to any portion of the vestibular system
What are the clincal signs of vestibular disease of the inner ear?
Head tilt
Ataxia
What are the two locations of vestibular disease?
Peripheral
Central
Where is the lesion in peripheral cases of vestibular disease?
internal ear receptors
vestibular ganglia
peripheral axons of VIII CN
Where is the location of the lesion in central vestibular disease?
Vestibular nuclei of medulla
Vestibular projection of the brain stem
Cerebellum or spinal cord
What are the four classifications of vestibular disease?
Congenital
Concurrent otitis
Idiopathic
Aural/Intracranial neoplasias
Why is it hard to diagnose congenitcal VD?
No gross or histological lesions
What dog breeds tend to have congenital VD?
Dobermans
German Shepards
Cocker spaniels
Beagles
Akitas
What cat breeds tend to have congenital VD?
Siamese
Tonkinese
Burmese
What are the causes of concurrent otitis media/interna that lead to VD?
Canine distemper
FIP
Erlichiosis
Toxoplasmosis
Neoporosis
Mycosis
Whats the most common cause of idiopathic VD in dogs?
Age
Where do neoplasias tend to come from that cause VD? What are they?
Neurofibromas or Schwannomas
From vestibulocochlear nerve
Term: Temporohyoid osteoarthropathy
Bony proliferative disease of temporohyoid articulation
What are two possible causes of temporohyoid osteoarthropathy?
Infectious agents
– or –
Premature DJD of the joint
What animals tend to get aural plaques?
Horse
> 1 year old
What are aural plaques thought to be caused by?
Papilloma virus
What is the gross appearance of aural plaques?
Raised
Well demarcated, hypopigmented, hyperkeratotic plaques
What do biting flies tend to cause on the external aural?
Stephanofilaria otitis
aka ear sore
What do biting flies tend to spread that cause ear sores?
S. zaheeeri
What is the gross appearance of ear sores?
Congestion to hemorrhaging
Severe crusting
Chronic = Alopecia + depigmentation
What type of ear related neoplasia do angora goats get?
Aural melanomas
What is thought to be the cause of aural melanomas?
UV light induction
What is the gross appearance of aural melanoma?
Single or black nodules
Superfical or Subcutaneous
What causes aural chewing in pigs?
Intese confinement
– and –
Docking tails
Where in the ear does cholestrol granulomas tend to occur in dogs?
Middle ear
What are the predisposing factors that can cause cholesterol granulomas in dogs?
Hemorrhage
Impaired auditory tube drainage
Dimished/Obstructed ventilation of middle ear
What is the gross appearance of cholesterol granulomas in dogs?
Benign
Expansile masses with concurrent otitis
Where is aural cholesteatoma found most in?
Middle ear
Middle-aged to Old dogs
What are aural cholesteatoma?
Beign cysts which can be locally destructive
What is most likely the cause of aural cholesteatoma?
Otitis externa/media
Leading to negative pressure
Leading to abnormalities in the tympanic membrane
Forms a cysts lined by cornifying stratified squamous epithelium
What is the gross appearance of proliferative, necrotizing otitis extrena in a cat?
Large, well demarcated erythematous plaques
Appear on concave auricular surface
Covered by thick, tan/brown keratinous debris
What are the histological features of proliferative, necrotizing otitis externa?
Superficial ecanthosis extending into follicles
Neutrophilic luminal folliculitis
Follicular hyperkeratosis
Necrotic keratinocytes on hair follicles
What are feline ceruminous cystomatosis?
benign, cystic, non-neoplastic proliferations of ceruminous glands on medial surface of auricle
Extend into external acoustic meatus
What is the gross appearance of feline ceruminous cystomatosis?
Glands are markedly dilated
Filled with brown, ceruminous secretions
