Unit 3 - Otitis Externa Flashcards
What clinical features are associated with otitis externa?
pruritis, pain, foul-smelling odor, and discharge
What are the predisposing factors that may lead to otitits externa?
Conformation/breed predispositions, behavior of the patient, environment, trauma, obstructive disease, and immunosuppressive diseases
What conformation/breed predispositions predispose patients to otitis externa?
long, tortuous ear canal, stenotic pinnae, hair in the external ear canal, and thick, dense hair at the opening of the external ear canal
What behavior of a patient can predispose them to developing otitis externa?
swimming or excessive bathing
What environmental conditions can predispose to otitis externa?
high environmental temperatures and high relative humidity increase the risk of otitis
What does the external canal consist of?
skin overlaying cartilage - auricular and annular cartilage
What part of the external ear canal does the auricular cartilage make up?
the ventral canal
What part of the external ear canal does the annular cartilage make up?
the horizontal canal
True or False: Only certain breeds have hair follicles in their ear canal.
False - all breeds have hair follicles in their ear canals, some just have hairier ears
When visualising the tympanic membrane, what structures can you see?
Pars flaccida, pars tensa, and malleus
1
pars flaccida
2
pars tensa
3
malleus
4
external ear canal
The pars flaccida can change appearance based on ______.
pressure
What primary factors can induce otitis externa?
ectoparasites, foreign bodies, allergies, scaling disorders, autoimmune skin diseases, and juvenile cellulitis
What ectoparasites can cause otitis externa?
Otodectes cynotis, Otobius megnini, Sarcoptes scabeii, Notoedres cati, Demodex, and Cheyletiella
What is the most common primary factor of otitis externa in the dog?
atopic dermatitis
What are the perpetuating factors for otitis externa?
bacteria, yeast, otitis media, erroneous treatment, proliferative/pathological changes of the external ear canal, and polyps
What are the most common bacterial isolates in inflamed ears of dogs?
Staphylococcus pseudintermedius, Proteus mirabilis, Pseudomonas aeruginosa
What are the most common bacterial isolates in inflamed ears of cats?
Staphylococcus pseudintermedius and Pasteurella multocida
What are some pathological changes that can occur in the ear?
inflammation, glandular hyperplasia, epidermal hyperplasia, additional inflammation, fibroplasia, and ossification
What is evidence based medicine?
conscientious, explicit, and judicious use of current best evidence in making decisions
What are ‘best practicies’?
Procedures/methods shown by research and experience to produce optimal results that are established or proposed by experts in a field as a standard for use - used to provide clinical practice guidelines
What are the best practices in the management of otitis?
- Use appropriate diagnostics
- Prepare the canal for treatment
- Choose treatment wisely
- Medications must be administered properly
- Use quality control to evaluate the environment
- Consider long-term maintenance therapy
- ID and control primary factors
What are the appropriate diagnostics for diagnosing otitis externa?
medical history, PE, otoscopic examination, cytology, culture and sensitivity, and diagnostic imaging
What are the keys/goals of otoscopic examination?
examine both canals, visualize the tympanic membrane, and do no harm (may need sedation/anesthesia as necessary)
What tools can be used for otoscopic examination?
otoscopes, pneumo-otoscopy, and video otoscope
What are the benefits to using a video otoscope?
increased magnification over hand held otoscopes, better light and clarity, and they give you the ability to adapt better for individuals visual defecits
What is the ‘key’ diagnostic test in otology?
cytology
True or False: Cytology should be done in both ears regardless if the disease is unilateral
TRUE
How do you perform an ear cytology?
- Introduce a cotton-tipped applicator gently into the horizontal external ear canal
- Roll the cotton swab gently onto a glass slide
- Heat fix sample (if greasy)
- Stain with Wrights, Diff Quik, or New Methylene Blye
- Rinse off the extra stain with water (do this by applying water to the non-stained edge and let it run down the slide until it turns clear)
- Air dry, or dry with cool blower
What is normal to find on an ear cytology?
keratinocytes, cerumen (ear wax), occasional bacteria (cocci or rods), and occasional yeast
What are you looking for on an ear cytology?
Presence of bacteria, including relative nubers, type (rods, cocci), and whether a pure or mixed infection is present
The presence of Malassezia or other fungi, including relative numbers, and if a mixed infection with bacteria
The presence of inflamatory cells: if present, a culture and systemic antimicrobial therapy is indicated
The presence of parasites
The presence fo other atypical cells - like neoplastic cells
If examining for ear mites, what should you do with your cytology?
Place the sample in mineral oil, cover slip, and then examine without staining under low power magnification
What are the indications for bacterial culture?
known resistant organisms, failure to respond to standard-of-care therapy, previous administration of (several) antibiotics, single population of rods on cytology, and concurrent systemic signs
What are the indications for diagnostic imaging of the ear canal?
clear loss of tympanic membranes, unable to adequately visualize the TMs, and recurring infections
What are the options for otic diagnostic imaging?
radiography, ultrasonography, MRI, and CT
What must you do prior to treatment of otitis externa?
treat the perpetuating factors, remove or control primary factors, and minimize predisposing factors of otitis externa
When should thorough cleansing of the ear canal be done?
after the otoscopic examination and collection of samples for cytology and culture - if indicated
What cleansing agents can be used for cleansing of the ear canal?
Ceruminolytic agents with or without drying agents
Should hair be removed pror to treatment of otitis externa?
It is highly recommened because it can prevent proper evaluation, is possibly a predisposing or perpetuating factor, and it blocks penetration of medication into the ear
What is the purpose of cleaning the ear canal?
Remove debris that causes irritation
Removes debris/hair that blocks movement of medication into horizontal canal
Removes debris that interferes with ‘self-cleansing’
Removes debris that can interfere with activity of active ingredients
Reduces the burden of microorganisms
What bacterial otitis externa infections are frequently associated with biofilm production?
Pseudomonas (40-90%) and Staphylococcus spp. (30% (otitis) - 96% (various))
What are the mechanisms of antimicrobial tolerance with biofilms?
antimicrobial depletion - agent doesn’t reach the biofilm
slow penetration - gives cells chance to initiate a stress response
stress response - cells change activity in response to challenge
altered microenvironment - metabolically inactive
persister cells - spore-like cells that can survivie an antimicrobial challenge
When is deep ear cleaning/flushing indicated?
When you can not clearly see the tympanic membrane
What is the goal of deep ear cleaning/flushing?
to thoroughly clean the ear
What techniques can be used to facilitate deep ear cleaning/flushing?
special catheters, teflon-coated catheters, and pump-suction instruments
What cleaning agents can be used for deep ear cleaning/flushing?
Ceruminolytic agents - squalene, DSS, urea, and carbamine peroxide
What cleaning agent is safe for the middle ear?
squalene
How is a teflon catheter used for deep ear cleaning?
Deep general anesthesia is needed, a teflon coated catheter is attached to an IV extension set and then is attached to a 3-way stopcock. The other 2 ports of the stopcock are attached to suction and a 60cc syringe (for saline). The clinician can direct the suction and flushing to specific areas in the ear using this technique
Cleaning techniques should be based upon what?
history, diagnostic results (organisms present), susceptibility patterns, and locations of infections, and owners abilities, perceptions, finances, etc.
What is animax (and similar products) made up of?
neomycin, thiostrepton, nystatin, and triamcinolone
What are the benefits of using animax?
good broad-spectrum action
What are the cons to using animax?
esthetics and ointment base
What is Tresaderm made up of?
neomycin, dexmethasone, and thiabendazole
What are the benefits of using Tresaderm?
Mild antibacterial and yeast, propylene glycol base, and good for first occurance
What are the cons to using Tresaderm?
Mild activity, must be stored refrigerated/warmed prior to use, and propylene glycol base (toxic effects to ear, can creaste a white substance that looks like pus)
What is Otomax/Mometamax made up of?
gentamicin, clotrimazole, betamethasone (systemic), mometasone (localized)
What are the benefits to using Otomax/Mometamax?
excellent ingredients and ointment base
What are the cons to using Otomax/Mometamax?
ointment base, gentamicin is ototoxic, packaging is terrible (can’t see how much is in bottle)
What is Posatex made up of?
orbafloxacin, posaconazole, mometasone furoate
What are the benefits to using Posatex?
broad spectrum, excellent anti-inflammatory, and excellent antifungal
What are the cons to using Posatex?
ointment base, terrible packaging, and pricing
What is Baytril otic made up of?
enrofloxacin and silver sulfadiazine
What are the benefits to using Baytril otic?
excellent activity agains Pseudomonas, broad spectrum, and aqueous base
What are the cons to using Baytril otic?
minimal anti-fungal activity and no glucocorticoid
What is easOtic made out of?
gentamicin, miconazole, hydrocortisone aceponate
What are the benefits of using easOtic?
good ingredients, excellent applicator, excellent anti-inflammatory
What are the cons to using easOtic?
gentamicin is ototoxic, total volume is insufficient, thicker ointment base, pricing
What is Surolan made up of?
polymyxin B, sulfates, miconazole, and prednisolone
What are the benefits to using Surolan?
good activity against Pseudomonas and excellent for Malassezia
What are the cons to using Surolan?
activity in presence of pus is questionale and is ointment based
What commercial otic medications are FDA approved drops?
Claro and Osurnia
What is Claro made up of?
Florfenicol (for gram positive cocci), terbinafine, and mometasone
What is Ketocort Otic made up of?
Ketoconazole and hydrocortisone
What is Osurnia made up of?
Florfenicol (for gram positive cocci) , terbinafine, and betamethasone
When are residual otic preparations indicated?
when clients cannot (or will not) treat daily
Aside from commercial otic products, long-acting topical medications, and residual otic preparations, what can be used to treat otitis externa?
opthalmologic products, flushes and products labeled for otic use, and compounding (do not try at home)
What would be a benefit to using compounding pharmacies?
they provide a wide range of active ingredients and a wide range of formulations - there are short half-lives
What would be a con to using compounding pharmacies?
poor qualitiy control and variability
What are the advantages of topical therapy?
delivers medication directly to the affected area, high concentrations, and inexpensive
What are the disadvantages of topical therapy?
Delivery deep into ear may be questionable, owner compliannce, poor penetration if middle ear is involved
Is there value to a culture?
yes - it informs clinician of organisms that are present, it identifies sensitive antibiotics, and may provide insight ito efficacy of other choices
What are the best choices for S. pseudintermedius?
Florfenicol, aminoglycosides, fluoroquinolones, and SSD
What are the best choices for Pseudomonas spp?
aminoglycosides, fluoroquinolones, polymyxin B, SSD
What are the best choices for Malassexia?
azoles, terbinafine, and nystatin
What are the best choices if there is a ruptured tympanic membrane?
fluoroquinolones
Wjat are the best choices if there are client compliance issues?
Claro and Osurnia
Choosing wisely is of NO value if?
proper application of treatment isn’t facilitated - dose, physical application of the dose, frequency of treatments, and duration of treatment
Dosage of medication is dependent on what?
the size of the ear canal
What is the recommendation for mLs in a dog that is less than 10kg?
0.4-0.5 mL
What is the recommendation for mLs in a dog that is 10-20 kg?
0.5-0.7 mL
What is the recommendation for mLs in a dog that is greater than 20kg?
1 mL
What are the negatives to using mL based on size versus using ‘drops’ that the label says to use?
it is a higher cost than using labeled doses and there are possible increased systemic effects
