Canine Otitis Flashcards
Predisposing factors for canine otitis?
- conformation
- obstruction
- excessive moisture/cerumen/hair
- cornification disorders
- immunosuppression
1* factors initiating canine otitis?
- FBs
- parasites (mites esp)
- hypersensitivity skin disease (atopic dermatitis/cutaneous food hypersensitivity)
- contact dermatitis beware topical ear products
- immune mediated dx
- others (misc)
What does granular knobbly external ear/pinna indicate?
Demodex
2* factors that cause ear idsease in an aborlam ear only or just contribute to pathoglogy?
- bacteria (s. pseudintermedius, pseudomonas (G- shift) proteus, klebsiella, E. Coli)
- yeasts - malasezzia
Perpetuating facotrs that prevent resolution of otitis and cause structural/functional changes?
- ear canal pathology (epidermal/dermal/adnexal)
- > stenosis of lumen
How long does otitits externa take to develop to middle ear disease?
- 50% cases extend within 6 months
4 main management aims of otitis tx?
- reverse perpetuating factors (skin disease and otitis media)
- resolve 2* infection(==skin disease)
- address 1* factors (skin disease)
- remove predisposing factos
which breed are predisposed to middle ear disease?
cocker spaniels
Does the tympanic membrane have to be broken for otitis media to occour?
no 70% cases in tact (heals up after rputure)
Which signs commonly thought to r/o otitis media actually do not rule out?
- Tympanic membrane intact
- imaging normal
- no neuro signs
What happens when acute otitis externa progresses to chronic otitis?
- shift from G+ nd malasezia to G- Pseudomonas
- or malasezia may be seen alone
(nb. multiple partially effective abx attempts may create resistance)
Diagnostics for ear infections?
> cytology
- selection for bacterial culture
- nature inflam response
culture
- does not replace cytology!!!
- NB. 20% repeatabilty of pathogen culture from identical swabs
- AND different pathogens may be grown frrom different sites (extrna v media etc)
Indications for surgery?
- tumours
- polyps
- irreversible stenosis
- aggressive medical tx failed/not possible/not wanted
- fulli nvestigation of all factors
common causes of tx failure?
- not long enough
- inadequate cleaning
- failure to id/tx otitis media and soft tissue changes
- failure to id/control 1* causes otitis
is conventional sensitivity testing of value for topical tx?
no - too many otherfactors affect it?
adverse effects of tx on outer ear??
>canal and TM.. - occlusion/maceration, epidermal turnover and migration, glandular changes, micro FB formation, atrophic defects > allergic/iritant dermatitis - prolonged exposure (pooling) - penetration enhancers - topical sensitisers
potential adverse effects of otic medications on middle ear?
> middle ear effects
- facial n (inc ps fibres) dmage
- symp neurons for occular innervation (Horner’s syndrome)
- Otitits media, cholesteatoma
potential adverse effects of otic medications on inner ear?
- diffusion into inner ear via round window
- ototoxicity (ear positiions) damaging vestibulo-cochlear nerve or inner ear (enhanced in OM)
- may occour weeks later
- rare
Golden rules for treating otic disease?
- stenosis = tx failure
- aural lavage under GA
- sample most proximal site affeted
- systemic Abx not indicated usually
- conventional bacterial sensitivity testing little value for topical tx
- avoid human reserved Abx
- monitor response with CYTOLOGY
- do not stop Abx before complete clinical AND MICRBIOLOGICAL cure
- keep cleaning!!
Potential systemic side effects following absorption of topical tx?
- GCs
- basal cortisol, ACTH stim, T4, insulin
> dont understand what this slide means, look up??
