Tricky InfectionsLinda Vogelnest BVSc MACVSc FACVScSpecialist Veterinary Dermatologist

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DemodicosisNon-contagious host-specific mitesnormal flora in most mammals

Disease:mite numbersimmunosuppression, older agegenetic T-cell defect (dogs)

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Demodicosis - Dogs3 mite speciesD. canis elongated mite (follicles, ear canals)D. cornei short-tailed mite (stratum corneum)D. injai long-bodied mite (sebaceous glands)

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Classical Demodicosis - DogsJuvenile onset (95% totally resolve with tx

Adult onset (>3yrs)Immunosuppressiondrug therapy [corticosteroids]hormonal diseases [hyperA, hypoT4] 50% idiopathic

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Classical Demodicosis - DogsPresenting Complaint Lesions: localised or generalisedAlopecia (well- to poorly-demarcated)Scaling, crusting, weeping dermatitis

Pruritus mild/moderate to absent

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Long-bodied DemodicosisD. injai greasiness & scaling*

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Demodicosis - CatsRare2 mite speciesD. cati elongated mite (follicles)D. gatoi stumpy-tailed mite (stratum corneum)PathogenesisImmunosuppressiondrugs (steroids), FIV, underlying dz (neoplasia) D. gatoi may be contagiouspruritic presentation!

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Demodicosis - DiagnosisSkin scrapingsdeep (follicular mites)capillary oozeavoid friable skin

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Demodicosis - DiagnosisLess sensitive but easier testsTrichogramSqueeze TapesTape impressions

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Demodicosis - DiagnosisDeep scrapings diagnostic:MITES = DEMODICOSIS (VERY rare from normal skin)

NO MITES = NO DEMODICOSIS except:Sharpei - thick skin difficult to extrude mitesPododermatitismay need to biopsy

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Demodicosis - PitfallsDemodicosis present & not recognisedscrapings not done (most often!)scrapings not deep enough (very rare)

Demodicosis absent, but tx on suspiciondespite negative skin scrapingsbiopsy if any doubt; DONT trial tx

Treatment insufficient duration (&/or frequency)

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Demodicosis Treatment DogsLocalised (1 to several small lesions)treatment not recommendedmostly self-resolve in similar time to tx

Generalised (whole body; large regions; >1 foot)intensive + sustained tx50% may self-resolve (juvenile)underlying dz (adult-onset)

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Demodicosis Treatment DogsTreatment duration

= single most important factor of txMUST continue beyond clinical resolutionrepeat scrapings (4 wkly) continue at least 4wks after 2nd neg scrape

3-month minimum tx course*

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Demodicosis Treatment DogsIvermectin = mainstay of txCattle injectable or sheep oral (Ivomec)300-600ug/kg daily oralweekly injections? unreliable (unless self-resolving anyway!)*

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Demodicosis Treatment DogsIvermectinDoramectinslow-release, cattle inj (Dectomax)variety protocols300-600ug/kg s/c wklyoral; eodless studiedless efficacious? sub-optimal frequency?*

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Demodicosis Treatment DogsIvermectinDoramectinAdvocate - imidacloprid + moxidectinRegistered monthlyIneffectivemay be adjunctive weekly*

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Demodicosis Treatment DogsIvermectinDoramectinAdvocate - imidacloprid + moxidectinAmitraz (0.5g/L)cattle powder (500g/kg)/liquid (125g/L)care with dilution

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Demodicosis Treatment CatsEasier than dogsIvermectin200-300ug/kg eod (with care)Advocate - wkly?Lime sulfurnot available Australia*

DemodicosisQUESTIONS??*

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DermatophytosisPitfalls & ChallengesIncorrect diagnosisTreatment challengesCatteriesPounds/sheltersZoonosis

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DermatophytosisHISTORICAL CLUESSpecies/BreedCats: long-haired, PersiansDogs: Yorkshire/JRTAgeYoung or older/immunocompromisedEnvironmental conditionsMultiple pet householdsHumid climates

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Clinical Clues - CatsHead (face, pinnae)Well-demarcated asymmetrical alopeciaSubtle patchy alopeciaMiliary dermatitis

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Clinical Clues - DogsWell-demarcated asymmetrical alopeciaExtensive severe formsYorkshire/Other Terriers: immunosuppressionKerions = highly inflammatory nodules

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Well-demarcated AlopeciaDifferentials?Bacterial PyodermaDemodicosisDermatophytosis*

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Dermatophytosis - DiagnosisCytologyTrichogramTape impressionfungal spores, hyphae

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Dermatophytosis - DiagnosisWoods Lamp~ 50% M. canis fluorescewarm up - 5mins easy to over-interpret:+ve = bright, iridescent green - hair shaftscan help with monitoring resolution

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Dermatophytosis - DiagnosisFungal cultureconfirms species/likely sourcesampleshairs (periphery of lesions)surface scaling (scrape)in-house Fungassaylab more reliable for IDfalse ve & +ve

Skin biopsyhelpful for uncertain cases/atypical cases

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Dermatophytosis - TreatmentYoung (

DermatophytosisQuestions??*

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OtitisVery common in dogsAcute diseaseOften relatively simple; poorly managed chronicChronic &/or severe diseaseOften poorly responsive &/or recurrentGood management plan relies on understanding dz pathophysiology 1, 2, perpetuating factors

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External EarPinnaExternal ear canalOuter vertical portion

Inner horizontal portion

Modified skin, surrounded by cartilage (mainly) & bone (short tube)

external ear canal flexibilityTympanic membrane

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Middle EarAir-filledConnects to pharynx (auditory tube)Closed by tympanic membrane

Bony ossiclesTransmit vibrations inner ear

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External Ear Canal DiseaseOtitis externaDog - extremely common: 15-20% dogs oncePredisposing Factors anatomyPendulous pinnaeRelatively hairy canal entranceGreater physical length

more poorly ventilated canals1 Disease

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External Ear Canal Disease1 DiseasesInflammatory: allergic, parasitic, endocrineNeoplasia: benign sebaceous/ceruminal gland

ATOPY*

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Canine OtitisImportant factors:PredisposingPrimarySecondaryPerpetuating

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Secondary FactorsBacteriaCocci - Staph, StreptRods - Pseudomonas, Proteus, E. coli, KlebsiellaYeastMalassezia pachydermatis

*inducing otitis only in combination with predisposing or primary causes

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Perpetuating FactorsChronic Inflammation

epi hyperplasia, hyperkeratosisdermal oedema, fibrosisceruminal gland hyperplasiacalcification thickening, folding, stenosis of canals

*preventing resolution of inflammation despite addressing causes

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Perpetuating FactorsOtitis media

keratin plugs, cells & secretionsreservoir of bacteria, yeastsDog: commonmajority = extension from OECat: less commonMore often primary OM

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Tympanic MembraneTympanic membrane alterations

thickening, loss of transparency

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My Approach to OtitisConsider history & clinical signsCollect samples for ear cytology & assess canalsOtoscopic exam if possible TreatmentAcute dzChronic/Severe dz

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Treatment: Acute DzHistory + CS - 1 factorsCytology (every patient!)sample + assess canal/discharge

Otoscopic exam (if possible)foreign bodies, ear mites

Treat 2 bacterial/yeast infectionsTM rupture?doesnt influence my tx choices!

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Treatment: AntimicrobialsBest guided by cytology (100% cases)Bacterial culture may be helpful (5%) rods (uniform population) & many previous treatmentscan be misleading; must interpret in light of cytologynot helpful if yeasts only, or mixed populations

Systemic rarely needed; often unreliable aloneTopical most effective; 3wk minimum

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AntimicrobialsYeasts on cytologymiconazole - Surolan, Easoticclotrimazole - Otomax, Mometamaxnystatin - Canaural, Topigen

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AntimicrobialsYeastsBacterial coccipolymixin B & miconazole - Surolanfusidic acid - Canaural

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AntimicrobialsYeastsBacterial CocciBacterial Rods (resistance more freq):gentamicin - Otomax, Topigen, Easotic, Mometamaxenrofloxacin - Baytril oticpolymixin B - Surolan*

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AntimicrobialsYeastsBacterial CocciBacterial Rods (resistance more freq)Combinations (rods + cocci &/or yeasts)Treat for rods firstCulture rarely indicated*

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Treatment: Acute DzTopical Treatment PrinciplesDrug choices based on cytologyVolume/method administration !!!Monitor cytology q. 2wkscontinue 1wk beyond cytological resolution

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Treatment: Acute DzAntimicrobials - mostlyEar Cleanersrarely during tx (unless very productive ears)may institute regular preventative treatment plan

Epi-otic, Bayer Clean Ear, Milos Ear CleanserPAW Gentle ear cleanerOtoflush (TrizEDTA)*

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Treatment: Acute DzAntimicrobials - mostlyEar Cleaners - rarelyAnti-inflammatories - mostlyImportantMost topical medicated drops containnot Baytril otic or Ilium ear drops*

*Treatment: Chronic/Severe

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Treatment: Chronic/SevereAs for acute ear dz plus:Flush (G/A) if copious/persistent discharge sterile saline, ~14g i/v catheter, 20ml syringevideoscope, 4g catheter through port more effectivemyringotomy if TM intact/suggestion middle ear dz

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Treatment: Chronic/SevereAs for acute ear dz plus:Flush (G/A)Treat 2 infections aggressivelybacterial culture MAY be helpful (if rods OR poor response)systemic antimicrobials more often

yeasts - ketoconazole 5mg/kg bid or itraconazole 5mg/kg sidbacteria - based on cytology & c/scompounded topicalssilver sulfadiazine/dex; ticarcillin/clavulinic acid/dex; enrofloxacin/dex

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Treatment: Chronic/SevereAs for acute ear dz plus:Flush (G/A)Treat 2 infections aggressivelyAnti-inflammatories essentialtopicals often sufficient

less potent: pred (Surolan, Canaural)more potent: betamethasone (Otomax), fluocinolone (Topigen)most potent: mometasone (Mometamax), hydrocortisone aceponate (Easotic)*

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Treatment: Chronic/SevereAs for acute ear dz plus:Flush under G/ATreat 2 infections aggressivelyAnti-inflammatories essentialtopicals often sufficientsystemic (v. inflamed ears + prior to flushing if stenotic)

pred 0.5-1mg/kg sidcyclosporine (severe hyperplasia e.g. Cockers)*

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Treatment: Chronic/SevereAs for acute ear dz plus:Flush under G/ATreat 2 infections aggressivelyAnti-inflammatories essentialSustained treatment & repeat cytology VITAL2wkly, until beyond cytological resolution min 6-8wks

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Treatment: Chronic/SevereAs for acute ear dz plus:Flush under G/ATreat 2 infections aggressivelyAnti-inflammatories essentialSustained treatment & repeat cytology VITALInvestigate for underlying dzhypersensitivities, endocrinopathies*

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Treatment: Chronic/SevereMinimise recurrences?Manage 1/predisposing factors if possibleswimming?hair removal?

Regular cleaningq. 1-2wks if tolerated

Pulse treatment (atopy)anti-inflam drops 1-2 times wklye.g. Surolan ( risk of antimicrobial resistance)best with vigilant ownerse.g. silver sulfadiazine (Flamazine)/dex compounded)

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OtitisQuestions??*

www.sashvets.com.autwitter: @SASHvets Phone - (02) 9889 0289Fax - (02) 9889 0431 Level 1, 1 Richardson Place, North Ryde 2113, Sydney, NSW

**inducing otitis only in combination with predisposing or primary causes*preventing resolution of inflammation despite addressing causes