Otitis Flashcards
Draw normal ear structure?
Label the tympanic membrane?
What types of ear disease are there?
Pinnal disease
Diseases affecting the ear flap
Otitis externa
Inflammation of the outer ear
Otitis media
Inflammation of the middle ear
Otitis interna
Inflammation of the inner ear
Outline different pinnal diseases?
Discuss ear margin seborrhea?
- Relatively uncommon
- Marked breed predilection in Dachshunds (Labradors and golden retrievers)
- Can be a feature of hypothyroidism
- Adherent keratin on both medial and lateral sides of the pinna
- Follicular casts and plugs may trap hair
- Rubbing produces erosions and ulceration
- Pruritus is variable
- Fissuring and secondary infection can be problematic
Discuss ear physiology?
- Temp 38.2–38.4 ˚C
- Humidity 88.5%
- pH 6.1/6.2 (lower compared to the skin)
- Otitis associated with rise in temp, humidity and pH
- Sebaceous glands
- Ceruminous glands
- Lipids + sloughed keratinocytes form cerumen
- Cerumen traps small FB
- Anti-bacterial/yeast
- Epithelial migration moves wax from TM to the external space (this happens in normal ear)
- Epithelial migration disturbed by inflammation, wetness, hyperplasia and physical blockage
- REMEMBER BUFFERING
- Ceruminous glands are modified sweat glands
What is the Normal flora in the ear canal?
- Gram +ve cocci predominate (but no growth in some dog’s ears)
- Similar species to those found on the skin
- Micrococcus spp.
- Coagulase negative staphylococci, Staphylococcus schleiferi and Staphylococcus pseudintermedius
- Streptococcus species
- Malassezia
- And many others
In treating otitis it is useful to consider?
Primary disease
e.g. atopic dermatitis, Otodectes cyanotis
Secondary disease
e.g. Malassezia, Staphylococci & Pseudomonas spp.
Predisposing factors
e.g. Hairy &/or pendulous ears, stenosis
Perpetuating factors
e.g. Ear canal hyperplasia, stenosis and scarring
P.S.P.P. system
What are some predisposing factors for otitis?
Conformation
- Excessive hair growth in canals (e.g. poodle)
- Hairy concave pinna (e.g. cocker spaniel)
- Pendulous pinna (e.g. basset hound)
- Stenotic canals (e.g. shar pei)
Excessive moisture
- Environment (heat & high humidity)
- Water (swimmer’s ear, grooming, cleaners)
Obstructive ear disease
- Feline apocrine cystadenomatosis
- Neoplasia
- Polyps
- Primary otitis media
- PSOM (primary secretory otitis media) in CKCS (or brachycephalic breeds), tumour or sepsis
Treatment effects
- Altered normal microflora (e.g. inappropriate cleaner)
- Trauma from cleaning or plucking (don’t rip out hairs in anagen as this will cause folliculitis)
What are primary causes of otitis?
Parasites
- Otodectes cynotis
- Demodex spp. (rarely seen only in ear usually systemic as well)
- Scabies
Foreign bodies
- Grass awns
Hypersensitivity
- Atopic dermatitis, food hypersensitivity, medications
Keratinisation disorders
- Primary idiopathic seborrhoea
- Hypothyroidism
Glandular disorders
- Cocker spaniels, English springer spaniels & Labrador retrievers have increased ceruminous glands
Miscellaneous
- e.g. feline proliferative & necrotising otitis externa
What is this?
Foreign body otitis
Grass seeds most common
- Classic time late spring to end of summer
Often stimulate violent response in the affected individual – sudden onset
Check the other ear!
Can be hidden in discharge and migrate into middle ear
Painful - chemical restraint is essential in most.
Grass seeds are most common in the summer
Beware the hair that looks like a grass seed and vice versa
Describe hypersensitivity otitis?
Hypersensitivity otitis
OE is a common complication of atopic dermatitis and food allergy (CAFR)
Primary otitis is often not recognised and so inadequately treated
Dogs and cats present when there is secondary infection
Prevention of recurrence
- Treat 1˚ disease
- Ensure perpetuating factors are treated
- Ensure owner knows to intervene early!
CAFR = cutaneous adverse food reaction
Discuss pathological changes in the external ear canal which perpetuate otitis?
Changes in canal wall
- Inflammation causing failure of epithelial migration
- Acute change: oedema, hyperplasia
- Chronic change: proliferative change, canal stenosis, calcification of pericartilaginous fibrous tissue
Changes in glandular tissue
- Hyperplasia of ceruminous and sebaceous glands, hidradenitis
n. b. hidradenititis – inflammation around ceruminous glands (more generally around sweat glands)
What the clincal features of Otitis externa?
Clinical signs of OE
- Aural pruritus or headshaking
- Mild to marked exudate
- Malodour
- Head tilt
- Deafness
Physical findings
- Erythema, swelling, scaling, discharge (otorrhea), malodour and pain
- Secondary
- pinnal lesions are common
- pyotraumatic dermatitis
- haematoma
What is this?
Scarring caused by pseudomas infection
What are the clinical signs of otitis media?
Variable clinical signs
- Often non-specific – pain?
- Most often signs of concurrent OE are the most obvious clinical signs
- Deafness
- Pain on eating
- Signs of OI if progression
- Consequences of OM
What are the clinical signs of horner’s syndrome?
- Damage to sympathetic nerves to the face
- Drooping of the eyelid on the affected side (ptosis)
- The pupil of the affected eye will be constricted (miosis), or smaller than usual
- The affected eye often appears sunken (enophthalmos)
- The third eyelid of the affected eye may appear red and raised or protruded (conjunctival hyperemia)
- Facial paralysis – CN VII
- Adult age Cocker Spaniels, Pembroke Welsh corgis, boxers, and English setters are most likely to experience this condition.
What is Primary Secretory Otitis Media (PSOM) in the CKCS?
It consists of a highly viscous mucus plug which fills the dog’s middle ear and may cause the tympanic membrane to bulge. PSOM has been reported almost exclusively in cavaliers.
Because the pain and other sensations in the head and neck areas, resulting from PSOM, are similar to some symptoms caused by syringomyelia (SM), some examining veterinarians may have mis-diagnosed SM in cavaliers which actually have PSOM and not SM.
- Presented for deafness or neck pain!
- Marked mucoid build-up in the middle ear
- Bulging middle ear noted on otoscopy
- Repeated flushing and myringotomy (3-5 times)
- Sputolysin (mucolytic) has been used by some
- Steroids are used to reduce mucous production
How is otitis media investigated?
- Appearance of the drum on video otoscopy
- Sampling of the middle ear for
- Bacteriology
- Fungal culture
- Cytology via myringotomy or ruptured TM
- Palpation of granulation tissue in the middle ear
- BAER (hearing testing)
- Imaging
How is a Myringotomy performed?
- Clean and dry the external ear canal as much as you can with saline
- Incision may be made using
- a 5-French polypropylene catheter (cut end to make sharper) or an open-ended tomcat catheter or a small wire (clitoral) swab
- Passed through either hand held or video otoscope
- Position:
- caudoventral aspect of the pars tensa to avoid damaging the tympanic germinal epithelium and the structures of the middle ear.
- Sampling:
- Pass swab(s) for cytology and bacteriology
- instilling and then withdrawing a small amount of sterile saline solution
- Flush with saline (± other agents depending on the cytology results)
How can radiography help diagnose otitis media?
- Insensitive way of assessing OM
- See thickening of the wall of the bulla in chronic disease
- Changes absent in many cases of OM
- Lateral oblique and open mouth views.
What can be seen here?
CT (X-ray computed tomography)
Can see bony changes after chronic pseudomonas otitis
How does a dog with bilateral fluid in the bullae look on MRI compared to a normal dog?
Should otoscopy always be attempted and if so how should it be done?
- Assistance from VN or owner for restraint
- Pain
- Do not look?
- Admit for chemical restraint?
- Treat for short period with a corticosteroid and then reassess?
- Look at the good ear first
- Head forward and slightly downwards
- Straighten canal and use a small cone
- Cones must be sterilised between use* (29% were contaminated in a study)
What does the nature of the exudate from the ear tell us about type of pathology?
What is stenosis a consequence of?
Chronic low grade trauma
Severe acute disease – untreated
Trauma
Mucinosis ± conformation in the Shar pei
Describe the cytology shown in picture A taken from a dog with otitis externa. Pictures are taken using the x 100 oil immersion lens
what are the significance of your findings?
Description
The slide shows Malassezia and cocci with a small amount of nuclear streaming
Neutrophils and other inflammatory cells are not seen
Significance
The presence of yeasts and cocci in cerumen is normal in small numbers. The number of organisms in this field is indicative of overgrowth and disease.
Malassezia and Staphylococci are often the first organisms involved in otitis
Describe the cytology shown in picture B taken from a dog with otitis externa. Pictures are taken using the x 100 oil immersion lens
what are the significance of your findings?
Description
The slide shows rods and marked nuclear streaming with a large nucleated epithelial cell
Significance
The presence of rods and nuclear streaming is indicative of a bacterial (rod) otitis. Pseudomonas sp., E.coli or Proteus are commonly isolated
Bacteriology should be performed in this case
Circle the products that would be most appropriate for use in a staphylococcal otitis?
Aurizon - marbofloxacin (fluroquinolone)
Posatex - orbifloxacin (fluroquinolone)
Easotic - gentamicin
Otomax - gentamicin
See pic for answers above is just to inform the pictures
Circle the products that would be most appropriate for pseudomonas otitis before culture results are available?
What is this and what is it resistant to?
Bacteriology results
Pseudomonas aeruginosa +++
Susceptible to
- Gentamicin
- Ticarcillin
Resistant to
- Enrofloxacin
- Marbofloxacin
- Neomycin
- Polymixin B
- Trimethoprim/sulphamethoxazole
- Amoxycillin/clavulanate
- Cephalexin
- Doxycycline
