Week 8 - Dermatology Flashcards

Question

What is Otitis Externa?

Answer 1

* Inflammation of the external ear canal epithelium +/- pinnal dermatitis -pinnal derma can occur without otitis externa * Incidence up to 20 % in dogs * Less common in cats at 6 -7%

Answer 2

- Latin for fin or wing - Plate of cartilage covered w/ epithelium - Wide variability in conformation - Mobile, channels vibrations - Aids in directional hearing - Vascular for heat exchange

Answer 3

- Vertical and horizontal canal - Modified squamous epithelium with numerous , large sebaceous glands & also ceruminous glands

Answer 4

- White oval shaped membrane - Divides external ear from middle ear - TM rupture → otitis media

Answer 5

* Any age , sex or breed * Certain breeds : increased risk→ think of the underlying risk factors those breeds may have * Dogs : 5 – 8 years of age * Allergic dermatitis most common * Cats : 1 – 2 years of age * Ear mites most common

Answer 6

* Head shaking * Scratching * Pain

Answer 7

* Erythema * Excoriations * Alopecia * Odor * Exudate: ceruminous or purulent * Ulcerations of otic canal +/- pinnae

Answer 8

Most cases result from a multifactorial etiology ! -PREDISPOSING FACTORS -PRIMARY FACTORS -PERPETUATING FACTORS

Answer 9

-Alter microenvironment of ear canal -Predispose to secondary infection 1. Breed conformation -pendulous pinna (cocker spaniels) --Not all pendulous pinnae breeds seem predisposed to otitis externa -Increased # of apocrine glands -Hairs w/in ear canal (hirsutism) - poodles -Narrow canal conformation (shar peis) 2. Humid environment -humidity in ear -Leads to maceration of tissue -Increased humidity due to : -Poor ventilation : anatomy (narrowed ear canals) -Frequent swimming / bathing -Obstruction of ear canal -tumors or polyps -inflammation →epithelial swelling 3. Inappropriate therapy * Mechanical trauma -plucking hair -“cotton” swabs * Irritant topical products * Improper antibiotic usage →opportunistic or resistant infections

Answer 10

* Initiate & directly produce inflammation of canal epithelium → turn on “incubator” * If identified & correction/management is possible may result in resolution of ear disease * Allergic dermatitis * Parasites * Foreign bodies * Cornification disorders (endocrinopathies) * Neoplasia * Immune mediated (pinnal dz)

Answer 11

* Bilateral pruritic otitis externa occurs in 50 – 80% of AD (pollen and mold) dogs -the ONLY clinical sign in 5 – 10 % of AD dogs * Bilateral pruritic otitis externa occurs in > 80 % of CAFR dogs -Only clinical sign in 20 – 25 %

Answer 12

* Otodectes cynotis: - 50 % of otitis externa in cats - 5 to 10 % of otitis externa in dogs -Contagious, 3 – 4 wk life cycle -Secondary infections & ectopic infestations can occur * Demodex canis *Otobius megnini (spinous ear tick)

Answer 13

* Acute , unilateral & painful * Plant material ( foxtails ) , dirt , dried medications , lodged hairs * Diagnose with otoscopic examination : ALWAYS LOOK!! * Can perforate tympanum

Answer 14

* Cerumen can be pro-inflammatory * Changes in glandular secretions * “Primary idiopathic seborrhea” * Secondary to other diseases... * Any that ↑ inflammation * Endocrinopathies ( decreased T4 , hyperadrenocorticism) * Metabolic (ex Zn responsive) * Immune-mediated

Answer 15

* Typically unilateral disease * Often hemorrhagic discharge * More common in dogs, more malignant in cats * Ceruminous gland ademomas & adenocarcinomas, squamous cell carcinomas

Answer 16

-pinnae more likely to be involved than external ear -pemphigus foliaceous -systemic lupus erythematosis -erythema multiforme -ischemic dermatopathy -juvenile cellulitis

Answer 17

* Do not initiate disease but perpetuates inflammation * Treatment is important for resolution of otitis externa * Bacterial infection * Yeast/fungal infection * Otitis media * Chronic path changes --Glandular change --Stenosis --Mineralization

Answer 18

* Often secondary to other factors * Common pathogens : COCCI -Staph. pseudintermedius -Strep sp. RODS -Pseudomonas sp. -Corynebacteria sp -Proteus sp. -Klebsiella * Resistance occurs!

Answer 19

-it is a rod -Not common inhabitant of normal ear canal or middle ear -Ubiquitous in environment, particularly aquatic environments * Causative agent in up to 35% of otitis externa and / or otitis media cases * Canine otitis Pseudomonas isolates often have moderate to high levels of antimicrobial resistance * Typically biofilm producing organism if you see ulcers in ear, most likely Pseudomonas Aeruginosa

Answer 20

* Impede delivery of antimicrobials * Provide protected reservoir for an organism * Enhance resistance mutation development to concentration dependent antimicrobials in terms of the bacteria 1. Promote bacterial physiology & metabolism 2. Provide essential nutrients 3. Create favorable environment for survival 4. Provide architectural integrity 5. Enable genetic transfer & intracellular communication

Answer 21

* Divalent cations, calcium & magnesium -Maintain structural integrity of biofilm →hold polymers together & provide binding strength for biofilm -Tris-EDTA -- chelates Ca -- so imparts biofilms * Pseudomonas biofilm is 30μm, Klebsiella is 15 μm, if a mixed growth even thicker biofilm! * Some Staph sp. are biofilm producers * Protein matrix created by bacteria -Primarily Staphylococcus species and Pseudomonas * Prevents host from responding to pathogen and prevents medications from treating * Appears as a gelatinous exudate that is brown, gray or yellow

Answer 22

* Malassezia: common secondary infection but also normal ear flora * Candida sp., Aspergillus are rare * Dermatophytes & systemic fungal mycoses → pinnal dermatitis

Answer 23

* Head tilt * Pain on opening mouth or chewing * Vestibular signs

Answer 24

* Maybe cause of recurrence for Otitis Externa * Not ruled out by intact Tympanic Membrane * 80 % of chronic otitis externa had otitis media (+ve culture) but 70% had intact TMb * Treat with systemic antibiotics +/- myringotomy & flush middle ear * Surgery (TECABO or ventral bulla osteotomy )

Answer 25

clinical signs & imaging

Answer 26

* PSOM , similar to “glue ear” in children * Middle ear effusion only, rarely external ear canal disease, may see bulging TMb * Cause may be dysfunction of Eustachian tube but no infectious etiology cultures negative * Cavalier King Charles Spaniel predisposed * Head shaking, sudden deafness, head tilt

Answer 27

* Epithelial hyperplasia & glandular hyperplasia * Fibrosis of dermis & subcutis * Calcification of auditory canal

Answer 28

* Indicated in otitis media, cytology w/ lots of rods, poorly responsive cases * Swab of canal and/or bulla sample Important to remember that.. * Sensitivities indicate serum not topical drug levels * Some antibiotics in otic preparations not included

Answer 29

* CT , MRI or radiographic bullae series * Indicated in cases of suspected otitis media or neoplasia * Normal appearance of bullae does not rule out otitis media

Answer 30

* Eliminate organisms * Clean ear * Decrease inflammation * Identify & manage risk factors

Answer 31

* Many topical otic preparations triple therapies : contain topical antibiotic, glucocorticoid & an anti-fungal * Examples : - Tresaderm® - Mometomax® - Gentizol ® - Claro ® * Things to consider when treating with topicals * Active ingredients * Viscosity of product * Tympanic membrane intact? -if not intact, then no aminoglycosides, or goopy meds * Owner compliance

Answer 32

* First line antimicrobials: neomycin, polymyxin B & gentamycin *common in triple therapies, chronic cases may have resistance to these antibiotics * Second line topical antibiotics: tobramycin, amikacin & fluoroquinolones: orbifloxacin (Posatex, Merial) & enrofloxacin ( Baytril Otic, Bayer)

Answer 33

* Silver sulfadiazine (SSD) has antibacterial properties against both Staph species & Pseudomonas

Answer 34

* Tris-EDTA ear flush is alkaline & aqueous * Pretreatment 20 to 30 minutes before applying topical antibiotics potentiates antimicrobial effects against Pseudomonas but not Staph * Tris-EDTA pretreatment soak → antibiotics resistant based on MICs may still have efficacy * May affect biofilms : chelates calcium * If neuro signs present avoid topicals * No licensed therapy for middle ear -Both drugs & vehicles could be ototoxic * If TMb is ruptured: avoid ointments -Triz EDTA flush or saline -Enro 2.5 %; 1:4 ratio w/ sterile water -SSD suspension

Answer 35

* Damage to the hairs in vestibulocochlear apparatus -Cochleotoxicity vs vestibulotoxicity or combination * Most commonly seen with systemic aminoglycosides, cisplatin and diuretics * Topically -Chlorhexidine, alcohols, aminoglycosides, polymixins, cerumenolytics * Fluoroquinolones, cephalosporins, TrizEDTA, dexamethasone are typically safe

Answer 36

1. Otitis media present 2. Marked swelling & hyperplasia of otic canal epithelium (tissue infection) 3. Ulceration of the otic canal (indicates deeper epithelial infection) 4. Adverse topical reactions occurred or suspected 5. Owners are unable to treat topically * Base selection on culture/ susceptibility * Injectable antibiotics impractical or risky for weeks of treatment * Fluroquinolones most common Rx for Pseudomonas * Marbofloxacin over enrofloxacin * Study: 28 % of dogs responded to txt w/ only oral marbofloxacin 5 mg/kg for 3 - 6 wks * Marbo has longer half life

Answer 37

* Modified cleaning / drying solutions : antimicrobial properties & mild ceruminolytic agents * Examples: Epi-Otic®, Oti-clens®, ChlorhexiDerm®, Malacetic Otic® Douxo micellar solution® * Any potent ceruminolytic agents : always flush with saline after use Acidic ear cleaners: * Epi- Otic advanced (Virbac) * Malacetic Otic (Dechra) Tris EDTA containing ear flush * T8 Keto (Bayer) * TrizUltra with Keto (Dechra)

Answer 38

* Cleaning otic canal removes bacterial & inflammatory debris→ improves efficacy of topical antimicrobials * Drugs can make contact w/ ear canal * ↓ purulent debris that inactivates some antimicrobial agents * Daily cleaning for chronic cases , q 48 to 72 hrs in acute cases

Answer 39

* In relapsing or refractory cases need to consider if there is otitis media * Advanced imaging: CT or MRI * Video otoscopy & myringotomy * Sample middle ear * Flush middle ear

Answer 40

* Glucocorticoids systemically, topically or both * Most effective way to diminish ear canal inflammation & hyperplasia * Antipruritic , anti-inflammatory , decrease sebaceous & apocrine gland secretion * decrease glandular hyperplasia * Often in combination topical products * Used as sole topical agent in allergic or ceruminous otitis externa * Provide some increased comfort * Systemic corticosteroids 0.5 to 2 mg/kg/day for 1 to 3 weeks, depending on any concurrent health problems * Higher potency topical corticosteroids more effective →mometasone, betamethasone, triamcinolone

Answer 41

* Recheck 10 to 14 days into therapy * Acute cases should respond within 1 to 3 weeks * Evaluations w/ cytology should occur every 10 to 14 days * Chronic Pseudomonas otitis may take 6 to 8 weeks but w/ ongoing clinical & cytologic improvement * Otitis media treated 6 to 8 weeks * Treatment continue 7 to 10 days past cytologic cure for chronic cases or Pseudomonas * ALWAYS do concurrent evaluation for predisposing, primary & perpetuating causes / risk factors * Especially critical if reinfection occurs

Answer 42

* Prevent infection and inflammation * Manage the underlying causes/ \risk factors! * Maintenance topical plan with ear cleaner * Consider judicious use of topical corticosteroid

Answer 43

* Cannot be medically managed * Chronic discomfort and pain * Risk of infection → meningitis * Chronicity or recurrence is due to -Failure to identify all causes -Inadequate management * Leads to permanent changes to ear canal & need for palliative surgical resection: TECABO Surgery is needed for AURAL MASSES