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information is provided by Provet for educational purposes only.
You should seek the advice of
your veterinarian if your pet is ill as only he or she can correctly advise
on the diagnosis and recommend the treatment that is most appropriate for
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Otitis externa is inflammation of the outer ear canal.
There are many primary causes of otitis externa including :
- Atopy - one of the commonest causes of otitis externa
- Food hypersensitivity (80% of affected cats and dogs reported to
- Contact hypersensitivity
- Autoimmune disorders
- Diseases of glands in the skin
- Hyperplasia of glands reported in Cocker Spaniels
- Foreign objects in the ear canal
- Grass awns
- Excessive hair
- Sand, soil, water
- Generalised diseases of keratinisation
- Primary idiopathic seborrhoea
- Hormonal disorders - hypothyroidism, sex hormone imbalances
- Ear mites (eg otodectes cynotis) - one of the commonest causes in cats
(50%) and dogs (10%)
- Flies, ticks and fleas - seen abroad - not in the UK
- Canine distemper virus has been implicated
Animals with narrow auditory canals and flop ears are more likely to develop
otitis externa than others. Cocker spaniels may develop glandular hypertrophy
and German Shepherd Dogs are reported to have an increased predisposition.
Working dogs and pet dogs that are exercised in rural areas are more likely to
get grass awns and other vegetative foreign objects in their ears.
SignsThere are many signs including :
- Reddening of the skin of the pinna
- A visible, often smelly, discharge in the outer ear canal. This can be
any colour from black, brown, red-brown, red, yellow, to off-white.
- Head shaking
- Scratching at the affected ear(s)
- Drooping of the affected ear
- Pain when eating (if complicating otitis media involves
- Holding the head to one side, (to the side of the affected ear)
- Walking in circles
- Fitting - if complicated by otitis media/interna
ComplicationsBacteria and yeasts are common secondary infections (they are rarely a
primary cause). Chronic otitis externa leads to thickening of the skin of the
pinna, with hyperplasia, hyperkeratosis, fibrosis and calcification. Swelling of
the tissues closes off the auditory canal leading to reduced natural
If the tympanic membrane is diseased or ruptured otitis media may develop
Thorough examination of the external ear canal with an auroscope is necessary to
identify the presence of a foreign object. To get good visibility may require
cleaning the wax and debris out of the canal and a general is needed in some
cases to get good visibility of the horizontal canal and tympanic membrane.
diagnostic tests that may be helpful include :
- Cytological examination of the discharge in the ear canal
- Culture an sensitivity testing of swabs taken from the canal
- Biopsy and histopathological examination
There are several forms of treatment :
- glucocorticoids for their anti-inflammatory and antipruritic effects.
Systemic antibiotics or corticosteroids have been reported to be helpful to
treat otitis media.
In chronic otitis externa the external ear canal can become so
narrow that the condition cannot be managed successfully with medications
alone. In such cases surgical intervention may be needed -
- Cleaning - use proprietory ceruminolytic product
- Removes foreign material and objects
- Removes excessive wax and other secretions as well as cellular debris
- Flush with sterile physiologic saline solution
- Polytherapy products are often used topically in the ear canal to treat
otitis externa. These are usually given as oil-based drops or creams and
include a combination of some or all of the following :
Bulla osteotomy is needed to treat persistent or recurrent otitis media.
- aural resection (opening of the lateral side of the vertical canal) or,
in the worst cases
- vertical canal removal (ablation) or total removal of the external
Good if treated early. Guarded with chronic otitis externa ..can have a
protracted course and .may result in surgery being needed.
Long term problems
Hearing loss. Recurrences are common