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25 Cards in this Set

  • Front
  • Back
List four factors that predispose to otitis externa
Anatomical, Excessive moisture, Inappropriate treatments, Systemic disease
Explain the role of anatomy in predisposition of otitis externa and what measures can be taken to minimize the factor:
A. narrow canals, hair in canals; pendulous pinnae; hairy concave pinnae; obstructions (neoplasm, polyps).
B. sx; shaving (change in breed standards-but I don’t think this will happen)
Explain the role of excess moisture in predisposition of otitis externa and what measures can be taken to minimize the factor:
A. high humidity; frequent swimming or bathing; obstruction; inflammation
B. Stop letting the dog swim; remove obstruction, treat inflammation; ear washes may be helpful to dry out the ea
Explain the role of inappropriatetreatment in predisposition of otitis externa and what measures can be taken to minimize the factor:
A. mechanical trauma; irritants; superinfections from altered normal microflora
B. E-collar to reduce mechanical trauma to the ears and stop using medications inappropriately.
List eight primary causes of otitis externa and give a diagnostic plan for each
1. Parasitic: Otodectes cynotis (50%); also demodex, sarcoptes, otobius megnini, eutrombicula
a. Ear swabs, skin scrapings, biopsy
2. Foreign body: plants; dirt; dry secretions; hair; usually acute onset with head shaking, pawing and pain
a. History; look with an otoscope.
3. Allergies: Atopy *most common cause of ear disease*; dietary hypersensitivity; contact hypersensitivity; drug reactions
a. See work ups for these disorders; also suspect if the problem does not resolve
4. Keritinization disorders: primary idiopathing seborrea; hypothyroidism; sex hormone imbalances;
a. treat the underlying condition if possible; manage the problems… some might not have a cure…. But then again her notes don’t say.
5. Autoimmune disease: Pimphigus foliaceous or erythematosus; Lupus erythematosis; bullus pemphigoid; EM; TEN; Vasculitis
a. Notes don’t really say; my guess is that you do biopsies; then treat as indicated in other sections (throw steroids at it)
6. Disease of the Ceruminous and Apocrine glands:
a. Nothing in notes about what this is, how to Dx or how to treat (her book talks about ceruminolytic agents which are soaps or surfactants that can be use to break up oily debris and flush them out.)
7. Ear tumors or polyps: sebaceous gland origin; ceruminous gland origin (smooth and lobulated); nasopharyngeal (papilliform like structures); any cutaneous tumor
a. These tumors occlude the lumen of the ear canal, and can be seen with an otoscope; work up the disease with biopsy and treat with surgical correction. In most cases dog tumors are begin and cats’ are malignant.
8. Viral: distemper; FeLV; FIV
a. Nothing in notes; book suggests that distemper has most often been associated with ear problems due to the replication site of respiratory epithelium. This can extend into the tympanic cavity and cause otitis media. It also mentioned that the immunosuppressant nature of this virus may allow for secondary bacterial infections to arise. Perhaps that is where FeLV and FIV fit in al well.
Explain the role of systemic disease in predisposition of otitis externa and what measures can be taken to minimize the factor:
A. pyrexia; immune suppression; dehibilitation; negative catabolic states
B. treat the underlying condition
Explain the concept of “perpetuation factors” in otitis externa
conditions that maintain, worsen, or prevent resolution of ear disease
How might you identify Bacterial infection of the ear, and what are some common ones
A. Do cytology; low numbers of “potential pathogens” may be found in “normal” ears
B. Most commonly see: Staph intermedius, Proteus, pseudomonas, E coli, Klebsiella, and corynebacteria
How might you identify Fungal infection of the ear, and what are some common ones
A. Do cytology; low numbers of “potential pathogens” may be found in “normal” ears
B. Malassezia (most common) but one also can find Candida, Aspergillus, Microsporum, Trychophyton, and Sporothix schenkii
What are some - Progressive pathologic changes, how might you identify them and what effect might they have stenosis- can see with otoscope; may be acute or chronic. Pathogenisis: changes drainage and ventilation of the ears allowing for secondary infection
B. loss of normal epithelia migration- if the germinal epithelium is damaged buildup of cells and oils in the ear; good media for secondary colonization
What percent of chronic ear infections lead to Otitis media
What is a possible sequelae to otitis media
may develop aural cholesteratomas (keratinous filled epidermoid cyst within the middle ear cavity)
T/F - Topical therapy is ineffective for otitis media.
Explain why bacterial sensitivity testing is of limited value in guiding therapy of otitus externa
The Kirby-Baurer method (disk diffusion method) is set up for certain breakpoints for specific bacteria, IN PLASMA. Since we treat otitus externa topically, who really cares what the concentration is in blood. Thus it is hard to predict how something will respond to the medication you have it on
Describe the therapeutic plan for otodectes infestations in a single household
treat all stages; some times recurrence can happen if treating just the adult form. May need to treat after clinical signs resolve until life cycle has been broken
Describe the therapeutic plan for otodectes infestations in a large population of indoor and outdoor cats
All animals in contact should be treated for these mites. The mite is very contagious between individuals. Some cats may not be showing signs but they can be asymptomatic carriers. In this case, separation of the indoor cats from those outside is probably best. Oh and good luck rounding up 30 outdoor cats to put drops in their ears…. Plus the reservoir in this case is probably wildlife, but bringing those thirty cats indoors to prevent re-infection sounds a bit scary
Explain the rational for use of corticosteroid-antibiotic combinations in topical therapy of bacterial otitus externa
Benefits of steroids: decrease edema, cerumen production, pain; facilitates cleaning; improves ventilation. Steroids are hopefully not absorbed systemically and but can cause local immunosuppression. They do however reduce the inflammation and allow for better action of the topical antibiotic to work on the infection
List the two most important diagnostic procedures for determining the etiology of otitis externa (dog): (Besides physical exam and history)
Ear cytology, otoscopy
List drugs and medications that may result in ototoxicity
Aminoglycosides, Metronidizole
How are debris and cerumen eliminated from the normal ear canal? What is epithelial migration?
the stratified squamous epithelium lining the external canal slowly migrates laterally from the deep canal to the opening of the ear canal. Keritinized S. corneum, cerumen, and any trapped debris are disbursed onto the pinna, where they can harmlessly fall away. This centripetal migration originates from the germinal epithelium located on the tympanic membrane. The process is a vital protective feature for normal otic health. Failure of epithelial migration (due to tympanic rupture, inflammation, injury or scarring) results in chronic accumulation of debris, cerumen, and desquamasated keratinocytes.
What are nasopharyngeal polyps and what problems do they cause?
These are papiliform like growths seen in young cats; benign growth covered by respiratory epithelium; signs include nasal discharge, dysphagia, gagging, and possibly head shaking (Tx: ventral bulla osteotomy with curettage of the epithelial lining, because simply cutting it out will not work, tends to re-grow).
How does otitus media in dogs differ from humans:
In dogs otitis media is believed to be due to direct extension from the external ear canal; in humans these most commonly occur due to a viral or respiratory infection with direct extension through the estuation tube.
What are the special considerations that should be made before selecting an aminoglycoside to treat otitis externa?
A) Can be inactivated by large amounts of organic debris (don’t use with ceruminous exudates)
B) - Decreased activity with acidic conditions (may not be effective if not using the right ear flush)
C) - Ototoxic- be careful that the tympanic membrane is not compromised
D) Neomycin can cause a contact dermatitis
What are the indications for lateral ear resection in a dog?
obstruction within the canal (anatomic or neoplasia) complications- may not fix the problem; leave an untreated underlying disease; progressive changes effect the horizontal ear canal
What are the indications for total ear canal ablation?
use when there is an irreversible change to the horizontal ear canal; complications- change in appearance, deafness, facial nerve dysfunction, vestibular nerve dysfunction, fistula