Otitis and Diseases of the Ear Flashcards
Perpetuating Causes of Otitis Externa
- Yeast
- Bacteria (cocci, rods)
- Chronic changes
- Otitis media
Acute signs of otitis externa
- Head shaking
- Ear scratching
- Head carriage
- Erythema
- Facial trauma
- Aural hematoma (scaphe)
- Malodor
- Debris
Chronic signs of otitis externa
- Lichenification
Pinna
- THin plate of cartilage covered on both sides by skin (sandwich)
What is the vertical canal?
- SEgment continuous with the pinna, surrounded by auricular cartilage
What is the horizontal canal?
- Segment from the vertical canal to the tympanic membrane; surrounded by annular cartilage
- Cartilage gives support, funnels sound, and protects the tympanic membrane
What is the tympanic membrane?
- Semitransparent membrane that separates the external ear canal from the middle ear
What are the two parts of the tympanic membrane?
- Pars flaccida
- Pars tensa
Pars flaccida
- Pink, small, loosely attached region forming the upper quadrant of the TM, contains small blood vessels
- May appear prominent and bulge in some dogs and could be mistaken for a mass
Pars tensa
- Remainder of the membrane
- Thin, tough pearl grey structure attached to surrounding bone by a fibrocartilaginous rnig
Stria mallearis
- Outline of the manubrium of the malleus that is visible through the TM where it attaches to the medial surface
- Manubrium has a hook that points rostrally in the dog
Label the parts of the ear
- Apex
- Scapha
- Lateral or caudal border of the helix
- Cutaneous marginal pouch
Where do you insert your otoscope?
- Intertragic incisure
Histology of the ear
- Extension of the skin
- External ear canal lined by stratified squamous epithelium, overlying the dermis
- Dermis contains numerous sebaceous glands and fewer ceruminal glands (modified apocrine glands)
- Density of the ceruminal glands varies among breeds, therefore so does the amount of waxy secretions
- Canals contain hair follicles, which also vary in density among breeds
What is cerumen?
- waxy debris in the canal consisting of sebaceous and apocrine secretions and desquamated epithelial cells
- Functions to trap foreign matter and may be antibacterial
Epithelial migration
- Self-cleaning mechanism of the ear canal
- Surface of the epithelium moves laterally from the inner horizontal canal to sweep debris out of the ear
Relative humidity and pH of the ear
88.5%
mean pH= 6.2
- Relatively stable in normal ears
Microflora normally in the ear
- The ear canal is host to lower numbers of yeast (Malassezia pachydermatis) and Gram Positive bacteria
What is otitis externa?
- Inflammation of the external ear canal
- No insight to cause of inflammation
What happens to relative humidity and pH with otitis externa?
- Significant rise in relative humidity and pH
What are the three Ps that cause otitis?
- Primary causes
- Predisposing Causes
- Perpetuating Causes
Primary causes
- Parasites
- Allergies
- Foreign bodies
- Disorders of Keratinization
- Neoplasia
- Autoimmune diseases
Parasites that cause otitis externa?
- Otodectes
- Otobius
- Demodex
- Sarcoptes/notoedres
Otodectes cynotis - who gets?
- Dogs and cats
Appearance of otodectes cynotis?
- Coffee grounds
Appearance of ears with otodectes?
- ears can be normal
- Often visualized during exam
Demodex mites that can cause otitis externa
- Canis
- Injai
- Catai
Demodex implication in otitis externa?
- Ear canals can be affected as part of generalized infestation and cause heavy cerumen accumulations
Where does Sarcoptes tend to cause problems with otitis externa?
WHat question may suggest Sarcoptic mange?
- Ear pinna
- If the owner is itchy, that’s a big clue
- Rarely affects the canal itself
Notoedres - where does it tend to cause problems?
- Pinna mostly
Most common parasite of the ear canal?
- Otodectes cynotis
Otobius megnini - common name? where is it seen in the US?
- Spinous ear tick
- SW
Eutrombicula alfreddugesi common names? Who gets? Lesions?
- Chiggers
- Seen on free-roaming cats
- Pruritic papules on ears, head, and neck
WHat is the MOST COMMON cause of persistent or recurring otitis?
- ALLERGIES (atopy, food, contact hypersensitivity)
Atopic pruritus areas
- Face, paws, axillae, inguinal
Atopic dermatitis - what % of atopic pets can develop otitis?
- Up to 80%
What % of pets with food allergies can have otitis externa?
- Up to 80%
- Some may ONLY have recurring otitis as a clinical sign (i.e. no pruritus)
- Food allergy is an important rule out in young dogs with recurrent otitis
Contact hypersensitivity otitis - what agents are generally implicated?
- Neomycin
- Propylene glycol
- Anything placed on the skin or ears can cause irritation
Foreign bodies as causes of otitis - examples of causes?
- Grass awns or fox tails
- Concretions of medications and/or long-acting medications like compounded BNT or Otipacs
Clinical appearance of dogs with foreign bodies
- Often acute onset, unilateral
Keratinization disorers that can lead to otitis?
- Primary seborrhea
- Sebaceous adenitis
- Hypothyroidism
- Cushing’s disease (?)
Primary seborrhea
- Disorder of increased epithelial turnover and proliferation of sebaceous secretions
Who gets primary seborrhea?
- Cocker Spaniels and Basset Hounds
What can primary seborrhea lead to that predisposes to otitis?
- Increased cerumen production - environment for microbial overgrowth
- Increased sebaceous secretions can produce altered fatty acids that are irritating to the canal
Sebaceous adenitis - how can it lead to otitis?
- Can affect sebaceous glands in the ear canal resulting in dry, hyperkeratotic canals
- Especially in Akitas
Hypothyroidism - how can it lead to otitis?
- Can cause seborrhea and increased epithelial turnover and proliferation of sebaceous secretions
Neoplastic causes of otitis externa?
- Inflammatory polyps
- Benign
- malignant
Apocrine gland cysts in cats
- Little brown cerumminous cysts
- If you poke them, it’s brownish in color
Autoimmune causes of otitis externa?
- Pemphigus foliaceus
- Systemic lupus erythematosus
List of primary causes of otitis?
- Parasites
What should you primarily think with predisposing causes?
- Think anatomy**
- Think lifestyles
- Don’t rule out primary causes those
Anatomical predisposing causes for otitis externa?
- Pendulous pinnae (think Cocker spaniels; Bassets)
- Stenotic ear canals (Shar Pei; Chow Chow; poor ventilation and microbial overgrowth)
- Increased hair (trap cerumen and debris; poodles and labradoodles)
- Increased ceruminous glands have a favorable environment for microbial overgrowth (German Shephard, Spaniels, Setters)
Lifestyle factors that can predispose to otitis externa?
- Swimming
- Grooming or plucking
- Overzealous cleaning
What do swimming, grooming/plucking, or overzealous cleaning tend to do to the ear that predisposes to otitis?
- It can become macerated and can lose its protective lipid barrier allowing microbes to overcolonize the area
Perpetuating causes of otitis externa
- Yeast
- Bacterial cocci or rods
- Chronic changes
- Otitis media
Which yeast tend to be involved in otitis externa?
- Malassezia pachydermatitis
Which bacterial cocci and rods tend to be involved with otitis externa?
- cocci: Staphylococcus
- Rods: E. coli, Proteus, Klebsiella, Corynebacterium, Pseudomonas
What % of dogs with chronic otitis externa can have concurrent otitis media, and what is the clinical significance?
- Up to 50-80% of dogs and cats with chronic otitis externa can have concurrent otitis media and can reinfect the external canal
Chronic pathologic/inflammatory changes associated with otitis externa as a perpetuating cause?
- Hypertrophy of ceruminous glands can lead to favorable microbial overgrowth
- Epidermal and dermal hyperplasia can lead to stenosis and decreased “Self-cleaning” leading to increased microbial overgrowth
- Calcification of fibrous tissue surrounding the cartilage can lead to irreversible (end stage) changes to the ear canal
Acute clinical signs of otitis externa?
- head shaking
- Ear scratching
- head carriage
- Erythema
- Facial trauma
- Aural hematoma
- Mal-odor
- Debris
- Stenosis of the external (visible canal)
Chronic signs of otitis externa
- Lichenification
- Thickening of ear canal cartilage
- Stenotic ear canal
- Ceruminal gland hyperplasia
Treatment errors that can perpetuate otitis
- Overtreatment can lead to maceration of the canal
- Under-treatment can lead to sub-therapeutic doses reaching the site of infection
Signs associated with Pseudomonas otitis?
- Mal-odor
- Fluid on palpation
- Purulent discharge
- Ulcerated ear canal
- Pain
What type of diagnosis is otitis?
- CLINICAL
History questions to ask with otitis externa?
- Age of onset?
- Recurrence?
- Pruritus?
- History of skin infections?
- Swimming/bathing?
- Hiking/hunting (foreign bodies)?
- Treatments?
PE steps for otitis externa?
- be thorough!
- Observe gait and mentation in room
- Palpate ear canals
- Open mouth
- Examine skin and paws
- Look for neurologic deficits
What can be suggested if a dog with an ear infection has pain opening the mouth?
- Middle ear infection
Otoscopic exam procedure for otitis?
- Look at both ears!
- Understand the anatomy
- Practice makes perfect
- Need a good otoscope and proper restraint
- Try to visualize the tympanic membrane
What neurologic deficits may be associated with otitis media/interna?
- Facial paralysis
- head tilt
- Nystagmus
What if you can’t see the tympanic membrane?
- Evaluate what you can see
- Are their neurologic deficits?
- many reasons including inadequate restraint, pain, waxy material blocking TM, severe stenosis
What should be done on all patients with otitis?
- Cytology!
- Doesn’t diagnose it, but does help you figure out how to treat
External ears for otic exam - what are you looking for?
- Look at the skin at the base of the pinna and pinna itself (e.g. crusting may indicate scabies; diffuse erythema may indicate underlying allergy)
- Smell both ears
- Palpate both ear canals for symmetry, thickening, fibrosis, and/or calcification
What can you consider if the canal is severely inflamed or stenotic and otic exam not possible?
- Anti-inflammatory course/dose of prednisone and recheck in 7-14 days
What is prognosis if canals palpate calcified (bone like)?
- Poor for cure with medical management
- Strongly consider surgery like TECA-BO as a salvage procedure
Ear cytology procedure description?
- Swab vertical canal at the junction of the horizontal and vertical canal
- Roll swab on the slide
- Stain with Diff Quick
- Examine at 100x (oil)
- Should be done in EVERY case of otitis, including recheck exams
What is the most important diagnostic test for otitis?
- Cytology, but must consider patient’s clinical signs
Mite prep for otitis?
- Roll swab in mineral oil on slide to look for mites and examine at 4-10x
- For demodex he recommends 10x and drop the condenser
When to culture for otitis?
- When you suspect pseudomonas
- Infection persists in face of appropriate treatment
- PMNs with no bacteria
What does the culture and sensitivity tell us?
- Systemic concentrations
- Can achieve 10-100x the concentration in the ear topically
When to do advanced imaging for otitis?
- Suspected media/interna
What is the best modality for otitis media/interna imaging?
- CT is the best modality to evaluate bone and bulla structures
- Can be expensive
- may need referral and anesthesia
Radiography for otitis media/interna?
- 25% of cases may not reveal abnormal changes; positioning is important; interpretation can be difficult; may need to request radiologist inteerpretation
Baseline lab data for otitis
- CBC
- Chem
- UA
- IF underlying disorder
- Might not be helpful in most cases of allergic diseases
4 main principles for managing otitis externa?
- Look for primary causes
- Address any predisposing causes
- Reduce inflammation
- Treat secondary infections
Looking for underlying disease - what are you looking for?
- Identify and/or address and primary causes
- Address or minimize any predisposing causes IF POSSIBLE
(For example, reduce swimming or excessive bathing)
Treatment volume for toybreeds/cats?
- 0.25cc
Treatment volume for small/medium dogs?
0.5cc
Treatment volume for large breeds?
1 cc
Rule of thumb for length of treatment?
- Twice a day (BID) for 7-14 days
What treatments should you AVOID if tympanic membrane is ruptured or patient has neurologic deficits?***
- Aminoglycosides
- Chlorhexidine
What are safe topicals if you suspect the TM is ruptured or patient has neurologic deficits?
- Enrofloxacin
- Miconazole
- Dexamethasone
What are three basic properties of ear cleaners?
- Ceruminolytic (break up wax)
- Drying agents
- Antimicrobials
Ototoxicity of ear cleaners
- Definitely possible
What ingredient can cause contact reactions in ear cleaners?
- Propylene glycol?
What does cleaning the ear do?
- Helps remove accumulated debris that can directly irritate the otic epithelium, prevents penetration of topical medications, and can inactivate some antibiotics
What is the proper way to clean the ear canal?
- Flood the canal with solution, massage the base of the ear canal for approximately 30-60 seconds, allow the pet to shake the head, wipe excess debris from pinna with a cotton ball/soft gauze/Kleenex
Examples of ear cleaners
- Epi-otic advanced
- Epiklean, etc.
What ear cleaners to use if TM is ruptured or damaged?
- Saline
- Squalene
- TrizEDTA (not a cleaner but more of a treatment for Pseudomonas)
How to clean ears that are more complicated or non-responsive to simple cleaning?
- Anesthesia deep ear cleaning using potent ceruminolytic agent such as squalene
- Important to protect airway with agressive ear flushes as fluid can be aspirated through the Eustachian tube
How useful are oral antibiotics considered for otitis externa?
- Debatable
- No longer recommended in people
- THink the trachea; no significant concentrations in the external ear canal
When might you use oral antibiotics with otitis? ANd how long would you use them for?
- Otitis media or interna
- 6-8 weeks
What do you base oral antibiotic selection on for otitis media and interna?
- Culture and sensitivity, ideally collected from the middle ear
Use of oral antifungals for otitis?
- Debatable
- Some dermatologists feel it helps
- Best to treat topically he thinks
Which oral antifungals might you use? Which is not appropriate in cats?
- Ketoconazole (NOT IN CATS)
- Fluconazole
What provides most anti-inflammatory effects?
- Corticosteroids (Topical, oral, side effects?)
- NSAIDs aren’t useful, so don’t use them
- Chronic endstage disease
WHen should you see improvement with steroids?
- 1-2 weeks
- If no improvement by then, it’s unlikely they can be managed medically
What will Dr. Mel use for very chronic/endstage otitis?
- Lowest effective anti-inflammatory dose EVERY OTHER DAY
- NEVER uses daily dosing long-term
What is important to communicate to the client for otitis?
- Critical to convey why otitis has happened and likelihood of recurrence
Keys to success with otitis?
- Open ear canal (difficult to treat if you can’t get medications in)
- Clean ear canal when possible
- Use LARGE VOLUMES of topical medications; use solutions rather than ointments if the canal is stenotic
- Frequent follow-up examinations
- ID and address, when possible, an underlying cause for the otitis
What age of animal tends to get ear mites?
- Young animals (dogs and cats)
Diagnosis of ear mites
- Mite prep using mineral oil
Topical treatments for ear mites
- pyrethrin ear products (eradamite, otomite+)
- Thiabendazole
- Milbemite
Systemic treatments for ear mites
- Selamectin (revolution) or moxidectin (advantage multi) 1 tx every 2 weeks for 3 consecutive treatments
- Isoxazolines (bravecto, Nexgard, Simparica)
Malasezzia otitis - what should you be looking for?
- Primary/predisposing causes
- It’s very common
How to diagnose malasezzia otitis?
- Cytology (Diff-Quick and 100x)
What is the most common organism isolated from acute otitis?
- Malassezia otitis
Treatment for Malasezzia otitis
- many products
- Clotrimazole (Mometamax)
- Miconazole
- Terbinafine
- Posaconazole
Bacterial otitis - which cocci?
- Staphylococcus
Bacterial otitis - which rods?
- E. coli
- Proteus
- Klebsiella
- Corynebacterium
Treatment for bacterial otitis
- Aminoglycosides (tympanic membrane must be intact; part of Mometamax)
- Florefenicol
- Polymixin B
What tends to be the timeframe of pseudomonas otitis?
- Chronicity
- Fluid can be heard or felt on palpation of the ear canals
- Painful canals or upon opening of mouth
- Ulcerative ear canal
- Purulent discharge
- Distinct clinical presentation (yeasty but also like death)
- Tends to be resistant
Mechanism of Pseudomonas resistance
- Antibiotics go into the cell and through efflux pumps, the antibiotics get pumped out
Diagnosis of Pseudomonas otitis
- Suspect with history and exam findings
- Cytology (PMNs with LOTS of rods; doesn’t play well with others)
- If it’s purulent debris, you really should be suspecting Pseudomonas
- if you find equal numbers of neutorphils, cocci, and rods, think non-Pseudomonas
- Culture to ID
- SEnsitivity is important, as it’s often resistant
Topical treatment for Pseudomonas otitis?
- TrizEDTA
MOA of TrizEDTA
- Punches holes in the wall of Gram negative bacteria
- Binds to calcium channels
- Chelates
- ALlows the bacteria to be more susceptible to treatment (use 15-20 min before treatment)
Antibiotics to use for Pseudomonas
- Enrofloxacin** (secret weapon)
- Tobramycin
- Silver sulfadiazine (SSD)
- Ticarcillin
- Polymixin B
- Corticosteroids
Components of the middle ear canal
- TM
- Tympanic bulla
- Auditory (Eustachian tube)
- Auditory ossicles
- Facial nerve
What is the Auditory tube?
- Short passage from the nasopharynx to the middle ear
Relationship of facial nerve and parasympathetic and sympathetic nerves to middle ear?
- Facial nerve courses near it
- Parasympathetic and sympathetic nerves course through the middle ear
Pathogenesis of Otitis media
- Often seen in patients with chronic otitis externa
- TM is composed of collagens Type 1 and 2, which weakens with infections
- RARELY develops through extension from auditory tube (cats with URIs)
- RARELY from hematogenous spread
Infectious organisms implicated with otitis media?
Most often bacterial infection
- Staph
- Streptococcus
- Pseudomonas
- E. coli
- Proteus
- Otherwise, fungal (Malasezzia, Aspergillus, Candida), foreign bodies, inflammatory polyps (cats), and masses
Clinical signs of Otitis media?
- history of chronic otitis - up to 50-80% can have OM
- +/- pain on opening of mouth (manipulation of TM joint affects the bulla)
- +/- Ruptured tympanic membrane
- +/- facial paralysis, Horner’s syndrome, head tilt
- Some may seem normal!
Diagnosis of otitis media
- What about the history might suggest?
- Chronicity
- Poor response to treatment (primary causes addressed)?
What on otoscopic exam suggests otitis media?
- mass
- Bulging, ruptured, or colored tympanic membrane
- Usually pars flaccida distending
What % of patients with Otitis media can have intact TM?
- 70-80%
Advanced imaging for diagnosis of OM, and what is preferred?
- CT** (allows you to evaluate bullae)
- Radiography
- MRI
- Ultrasound
What is the name of the procedure often done to collect fluid and material from the middle ear?
- Myringotomy
What is the purpose of the myringotomy?
- Fluid/material collection from the middle ear
- Helps you collect a sample for culture and sensitivity
Cost of myringotomy
$1500-3000
Why is a culture and sensitivity important for otitis media?
- Up to 90% can have different external/middle ear results
What is the purpose of flushing the middle ear during a myringotomY?
- Diagnostic and therapeutic
How quickly can TM heal if ruptured?
Within 12 days (2-4 weeks)
What are you aiming to puncture with a myringotomy?
- Pars tensa
Treatment of otitis media?
- 6-8 weeks with a systemic antimicrobial ideally based on C&S from middle ear
- Topical treatment (non-ototoxic; TrizEDTA, saline, squalene, Baytril, miconazole)
- Want high volume topicals
Prognosis for otitis media?
- Guarded
- Recurrences are possible
- VBO (Ventral bulla osteotomy) may need to be considered
- still need to look for primary causes
- May need symptomatic treatment if facial nerve is involved and secondary exposure keratitis develops (e.g. artificial tears)
