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Otitis Externa - Cat and Dog (view source)
Revision as of 22:37, 6 September 2011
, 22:37, 6 September 2011no edit summary
==Aetiology==
==Aetiology==
There are three areas which regroup the causes of otitis externa.
There are three areas which regroup the causes of otitis externa.
:'''Predisposing factors''' increase the risk of development of the disease.
'''Predisposing factors''' increase the risk of development of the disease.
:'''Primary factors''' directly cause the otitis.
:'''Perpetuating factors''' prevent the resolution of otitis externa once it develops.
'''Primary factors''' directly cause the otitis.
'''Perpetuating factors''' prevent the resolution of otitis externa once it develops.
===Predisposing factors===
===Predisposing factors===
===Primary factors===
===Primary factors===
<u>Parasites</u>: ''[[Otodectes cynotis]]'', ''Sarcoptes'', ''Demodex'', ''Neotrombicula'', ticks
<u>Parasites</u>: ''[[Otodectes cynotis]]'', ''[[Sarcoptes]]'', ''[[Demodex]]'', [[Trombicula autumnalis|''Neotrombicula'']], [[:Category:Ticks|ticks]]
<u>Fungi</u>: Dermatophytosis
<u>Fungi</u>: [[Dermatophytosis]]
<u>Allergies</u>: atopic dermatitis, diet, contact
<u>Allergies</u>: [[Atopic Dermatitis|atopic dermatitis]], diet, [[Contact Dermatitis|contact]]
<u>Foreign bodies</u>: grass seeds, grass awns,
<u>Foreign bodies</u>: grass seeds, grass awns,
<u>Abnormal epidermal turnover or sebum production</u>: [[Seborrhea|seborrhea]], endocrinopathy, nutritional problems, sebaceous adenitis
<u>Abnormal epidermal turnover or sebum production</u>: [[Seborrhea|seborrhea]], endocrinopathy, nutritional problems, [[Sebaceous Adenitis|sebaceous adenitis]]
<u>Primary keratinisation defects</u>: [[Seborrhea|idiopathic seborrhoea]]
<u>Primary keratinisation defects</u>: [[Seborrhea|idiopathic seborrhoea]]
<u>Autoimmune disease</u>: pemphigus foliaceus
<u>Autoimmune disease</u>: [[Pemphigus Foliaceus|pemphigus foliaceus]]
<u>Miscellaneous</u>: juvenile cellulitis
<u>Miscellaneous</u>: [[Juvenile Pyoderma|juvenile cellulitis]]
===Perpetuating factors===
===Perpetuating factors===
<u>Bacteria</u>: ''S. intermedius'', ''Pseudomonas aeruginosa'', ''Proteus''
<u>Bacteria</u>: ''S. intermedius'', ''[[Pseudomonas aeruginosa]]'', ''[[Proteus]]''
<u>Fungi</u>: ''Malassezia pachydermatis
<u>Fungi</u>: ''[[Malassezia pachydermatis]]
<u>Topical treatments</u>: innapropriate use of topical treatments
<u>Topical treatments</u>: inappropriate use of topical treatments
<u>Progressive ear pathology</u>: ulceration, glandular hypertrophy and atrophy, thickened, folded canals
<u>Progressive ear pathology</u>: ulceration, glandular hypertrophy and atrophy, thickened, folded canals
<u>Otitis media</u>
<u>Otitis media</u>
==Clinical signs==
==Clinical Signs==
The animal will present with a history of '''head-shaking and ear scratching''', either acute-onset and severe or chronic and intermittent.
The animal will present with a history of '''head-shaking and ear scratching''', either acute-onset and severe or chronic and intermittent.
The ears may show evidence of '''self-trauma, erythema, and primary and secondary lesions'''. There may be pinnal deformities and the ear canal may feel thickened on palpation.
The ears may show evidence of '''self-trauma, erythema, and primary and secondary lesions'''. There may be pinnal deformities and the ear canal may feel thickened on palpation.
The animal may present with an '''aural haematoma''' from head-shaking if it is severe.
The animal may present with an [[Aural Haematoma|'''aural haematoma''']] from head-shaking if it is severe.
There may be '''discharge''' coming from the ear which may be brown and waxy or purulent and green.
There may be '''discharge''' coming from the ear which may be brown and waxy or purulent and green.
'''Medical therapy''' may be useful:
'''Medical therapy''' may be useful:
:'''Oral corticosteroids''' can be given for a short period at a high dose to open constricted canals and improve topical treatment efficacy.
'''Oral corticosteroids''' can be given for a short period at a high dose to open constricted canals and improve topical treatment efficacy.
:If there is a bacterial otitis, '''oral antibiotics''' are useful.
:If ''[[Otodectes cynotis]]'' is detected, a general topical or systemic '''antiparasitic''' is indicated as this parasite can invade sites other than the ear.
If there is a bacterial otitis, '''oral antibiotics''' are useful.
:Many '''topical treatments''' are available for otitis externa cases. These usually provide a '''combination''' of anti-bacterial, anti-fungal, anti-parasitic and anti-inflammatory agents.
If ''Otodectes cynotis'' is detected, a general topical or systemic '''antiparasitic''' is indicated as this parasite can invade sites other than the ear.
Many '''topical treatments''' are available for otitis externa cases. These usually provide a '''combination''' of anti-bacterial, anti-fungal, anti-parasitic and anti-inflammatory agents.
Duration of treatment should continue until the infection is resolved.
Duration of treatment should continue until the infection is resolved.
Animals should be examined and '''cytology swabs taken every week''' until there is no cytological evidence of infection.
Animals should be examined and '''cytology swabs taken every week''' until there is no cytological evidence of infection. This usually takes '''2-4 weeks''' for acute cases. Chronic cases may take months to resolve and therapy may have to continue for the rest of the animal's life.
This usually takes '''2-4 weeks''' for acute cases.
Chronic cases may take months to resolve and therapy may have to continue for the rest of the animal's life.
<u>Prevention:</u>
<u>Prevention:</u>
'''Palpation''' of the ear canals and '''radiographs''' will help determine if there are chronic changes to the ear canals such as calcification.
'''Palpation''' of the ear canals and '''radiographs''' will help determine if there are chronic changes to the ear canals such as calcification.
===Lateral wall resection===
===Lateral Wall Resection===
This can be performed at an early stage to increased '''drainage and ventilation''' of the external ear canal.
This can be performed at an early stage to increased '''drainage and ventilation''' of the external ear canal.
Harvey, R. (2001) '''Ear diseases of the dog and cat''' ''Manson Publishing''
Harvey, R. (2001) '''Ear diseases of the dog and cat''' ''Manson Publishing''
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