SA - otitis Flashcards
what line the outer ear canal
skin with ceruminous and sebaceos glands
what lines the middle ear
simple sq-cub cells
some cilia
goblet cells
name 3 parts of the tympanic membrane
pars flaccida (floppy) stria mallearis (middle) pars tensa (tense)
what is the biggest difference bw dog and cat ears
cat - v large round bullae, small aperture into inner ear
dog - more triangular bulla, wide aperture
how does the outer ear self clean
cerumen catches material inc forein mat, microbes and old kcytes
epithelial migration using kcytes (living)
how does the middle ear clean
drains fluid via auditory tubes, which also equalises pressure either side of tymp membrane
what are the 3 Ps
primry factors (hypersensitivity reactions acronym - PAINFREE)
predisp
perpetuating factors
what does PAINFREE stand for (acronym for primary causes of otitis
parasites allergic skin dz (cAD) immune mediated (II+III, rare) neoplasia/ polyps fx bodies (grass seeds) rare causes (idiopathic) epitheliasation defect endocrinopathy
name 2 parasites which cause otitis
otodectes cyanosis
demodex canis/cornei
why do neoplasia/polyps cause otitis
block cleaning mech
types = Ceruminus g adeno-/-carcinoma and cystomatosis..
what 3 endocrinpathies often lead to otitis
hypothyr
HAC
DM
what might cause an epitheliasation defect
1ry seborrhea
vit A dermatosis
what are the three predisposing factors
conformation
environ (swimmer, humid)
iatrogenic (over cleaning)
perpetuating factors are those which prevent resolution, name 3 broad categories
MO inf
pathological changes
otitis media
name 2 g+ cocci and 2 g- bacilli which can cause otitis
g+ = staph pseudointermedius and strep canis g- = pseudomonas aeruginosa and proteus mirabilis
what type of pathological changes would impede healing
chronic inflm - hyperplasia (CG and epi), calcification, osteomyelitis, all –> stenosis
how does OM develop
rupture of TM OR asc inf from the resp tract if epithelial transport fails
after a full CE, a specialised otic exam takes place, desc
external palp (normal, pruritis = otodectes/malassezia, pain= g-, stiff = hyperlasia etc) otoscopic ex = ID 1ry and perpetuating factors and integrity of TM
what might be used to reduce hyperplasia if its too pronounced to conduct otoscopic ex
gcort (predn) for 2wks
what dx tests are there
cytology, parasites, C+S
imaging
otoscopy
otic lavage (if TM intact)
why is cytology useful (cotton smear)
quick, in house, easy, cheap
assess ext and middle ear
can assess reaction to tx
diff sterile from MO inflma
is C+S a gold std test in otitis investigation
NO. needs to be interpreted with cytology, not to be used for assessing response to tx
desc the normal radiological features of the ear
air filled, bulla is smooth and thin walled
how should position a dog for a ear xray
D-V as positioning easy, bullar closer to plate. alternative = R-Cd mouth as allows more comparison.
ETT are a problem - often take out for this. other positions superimpose or dont allow comparison of the 2 bullae
what is CT best for
bony lesions
what is MRI best for
ST images
how long does CT and MRI take
CT - 5mins
MRI - 40m
why are video-otoscopy useful
can see middle ear
cytology + culture + neoplasia samples can be taken
polyps can be removed
tx can be given
in the management of otitis, what is the 1st step to tx
resolve the perpetuationg factors - NSAIDs, sx, lavages, abx..
how can pathological changes be resolved
only some can firstly, but give csteroids - reduce itching, dec secretions, and reduce scar and proliferative change
if sx required to resolve pathological changes, what might be possible
TECA (total ear canal ablation)
bulla osteotomy
salvage procedures basically..
where should antimicrobial be administered to tx OE and OM
topically (if TM intact). — OI needs systemic and if any osteomyelitis with TM that does too
how can you control predisp factor?
wash after swimming remove hair dont let O over wash clip around ears clean droopy ones 1/wk
what is a good way to control dry waxy ears, that are malassezia prone?
propylene glycol
whats a good way to prevent bacterial inf in moist ears
chlorhexadine
what are the RF poss from tx
canal or TM trauma vestibular syndrom horners deafness irritation, sensitivity or ototoxicity
