Derm - Ear disease Flashcards
What are the 4 types of factor to consider in cases of otitis externa?
Primary
Secondary - aggravate it
Predisposing - more likely to develop
Perpetuating - more likely to continue
What is the most common primary cause of otitis externa?
Allergic skin disease eg. atopic dermatitis, cutaneous adverse food reaction or contact dermatitis
What primary factors can cause otitis externa?
Allergic skin disease
Ectoparasites
Foreign bodies
Tumours
Autoimmune
Hypothyroidism
What secondary factors can exacerbate otitis externa?
Upsetting the ear microclimate
eg. inappropriate topical medication
Microbial overgrowth
Opportunistic infection - pseudomonas
What predisposing factors can increase the risk of getting otitis externa?
Conformation of the ear - floppy ears, narrow ear canals
Water/humidity in the ear - swimming
Inappropriate overcleaning
Trauma
Neoplasia - blocking ear canal
What are some perpetuating factors that can prolong otitis externa?
Lots of sebaceous glands producing cerumen - upregulation causing excess production encouraging microbial overgrowth
Excess cleaning can encourage upregulation
Stenosis of the ear canal due to chronic infection
What does chronic proliferative otitis externa cause?
Scarring, stenosis, deformity of the ear canal
Irreversible calcification of the cartilage
This is a perpetuating factor
What are the clinical signs of otitis externa?
Head shaking, scratching, pain
Ear canal firm on palpation
Discharge - cerumen, purulent or dark and tarry
Neuro signs - facial nerve paralysis, Horners syndrome
What nerves are located in the inner ear?
Facial nerve and vestibulocochlear nerve
What diagnostic tests can you do for ear disease?
Cytology of ear discharge
Tape impressions of skin folds
Culture
When should you culture ear discharge in ear disease?
When not responding to antibiotic treatment
When risk of antimicrobial resistance
When you find rods on cytology
What diseases do rods suggest if found on cytology from ear discharge?
Pseudomonas
E. coli
Klebsiella
What diagnostic tests should you do if you suspect middle ear disease (otitis media)?
Radiography
CT scan of tympanic bullae
What are signs of otitis media on CT scan?
Stenosis of external canal
Sclerosis, thickening of temporal bone
Sclerosis, thickening of tympanic bullae
Soft tissue opacity in bullae
How are cats middle ears different to dogs?
The have a bony septum in middle ear
How should you treat allergic skin diseases causing otitis?
Once/twice weekly ear cleaner and topical anti-inflammatories
Systemic glucocorticoids if this doesnt work
Why is pseudomonas difficult to treat?
Biofilm formation hides it from treatment, increases resistance
How do you treat pseudomonas?
PCMX
Marbofoxacin - fluoroquinolones
Gentamicin
Surgery?
What parasite can cause otitis?
Ear mites - otodectes cynotis
Some cats are very hypersensitive to them, others show no signs
How do you treat otodectes?
Selamectin and moxidectin
Canaural, surolan
Isoxazolines
What get polyps in their ears?
Cats from 5 months ot 5 years
What are polyps in the ears?
Benign inflammatory lesions located in the nasopharynx
What are the clinical signs of polyps in the ears?
Persistent aural discharge
Otitis
Head shaking
Scratching
Head tilt
Nystagmus
Which if these is not a primary cause of otitis externa?
A. grass seed
B. atopic dermatitis
C. keratinisation disorders
D. pseudomonas
E. otodectes cynotis
D. pseudomonas
Because it doesnt start the inflammatory process - only becomes a problem after inflammation already present
Is otitis media a predisposing factor for otitis?
No - it is a perpetuating factor as it is only there because it has already had an ear infection before, makes it more likely to continue
Is food allergy a predisposing factor for otitis?
No - it is a primary cause
What is an aural haemotoma?
A blood filled swelling on the inner surface of the pinna
What causes an aural haematoma?
Traumatic cartilage fracture and blood vessel rupture, separating the auricular cartilage from the skin
What are the treatment options for aural haematoma?
Do nothing - not good
Corticosteroids - ineffective
Aspiration, flushing - recurrence likely
Small incision and place haematoma tube - drips, not tolerated well
Surgical repair
What must you do in cases of aural haematomas?
Identify and treat the underlying condition eg. otitis
What is the prognosis of surgical repair of an aural haematoma?
Excellent provided the underlying cause is addressed
What is the simplest method of surgical repair of a aural haematoma?
S shaped incision
Then flush, remove clots
Add multiple staggered longitudinal sutures over whole haematoma incorporating the cartilage
Incision left open
Cover in dressing and bandage
What should you do if there is material deep in the external ear canal?
GA and ear flush
What are the complications of GA and ear flush?
Tympanic membrane damage
Neuro damage
Pain from irritation to the ear canal
Aspiration of fluid
What type of procedure does GA and ear flush count as?
Dirty
What types of suture should you use to repair the pinna from traumatic wounds?
Vertical mattress suture and figure of 8 suture
When do you need to do a pinna resection?
Resection of neoplastic masses
What ear procedure is illegal in the UK?
Ear cropping
What is the name of the procedure when the lateral part of the vertical ear canal is resented so there is a direct opening into the horizontal canal?
Lateral wall resection
What is a lateral wall resection used for?
Excising masses located in the lateral part of the ear canal
NOT for treatment of otitis externa
What is a myringotomy?
Surgicla puncture of hte caudo-ventral tympanic membrane
When do you perform a myringotomy?
Otitis media
Biopsy of a mass within the bulla
When is a tympanostomy tube (grommet) placed?
Primary secretory otitis media (glue ear)
What dogs get primary secretory otitis media (glue ear)?
Cavalier King Charles Spaniels
What is a TECA?
Total ear canal ablation - removing the entire vertical and horizontal ear canals
What is a TECA always performed alongside?
Bulla osteotomy
When do you perform TECA surgery?
Chronic otitis externa
Neoplasm in horizontal ear canal
What are complications of TECA surgery?
Facial nerve injury
Chronic sinus tract development - para-aural abcess
Wound breakdown, haemorrhage
Vestibular signs
What is the prognosis of TECA surgery?
GOod for otitis externa if avoid complications
Mixed for neoplasia - guarded for SCC
What is a ventral bulla osteotomy?
When the chamber of the bulla are opened and gently cleaned/flushed
When is ventral bulla osteotomy performed?
For removal of nasopharyngeal polyps in cats
What are some complications of ventral bulla osteotomy?
Horners
Vestibular disease
Polyp regrowth
Haemorrhage
Facial nerve damage
What auricular nerve blocks can be used for ear disease/surgery?
Auriculotemporal nerve
Greater auricular nerve
