Approach to Otitis Externa PDF

APPROACH TO OTITIS EXTERNA MIRINDA VAN SCHOOR Learning Outcomes: Otitis Externa Define the term otitis externa. Recognise normal and abnormal anatomical appearance and describe pathological processes that affect the external ear. Describe common aetiologies of, and the PSPP approach to o...

APPROACH TO OTITIS EXTERNA MIRINDA VAN SCHOOR Learning Outcomes: Otitis Externa Define the term otitis externa. Recognise normal and abnormal anatomical appearance and describe pathological processes that affect the external ear. Describe common aetiologies of, and the PSPP approach to otitis externa. Identify the various diagnostic procedures to determine aetiology (history, examination, otoscopy, cytology, culture) Discuss appropriate medical and surgical management 2 Normal Anatomy (revise anatomy and pathology where applicable) #universityofsurrey ©Hills pet Nutrition 3 Normal Anatomy The cartilage and bony process of the external ear and the tympanic membrane are covered by skin. The skin of the normal ear has a thin stratified keratinising epidermis and a thin dermis containing adnexal structures : Hair follicles Sebaceous glands Apocrine glands #universityofsurrey Dr. R. Roodt 4 Normal Anatomy Sebaceous glands - sebum Apocrine glands - modified sweat glands Hair follicles – density of hair follicles is variable. Horses: devoid of hair in the lower (proximal) ear canal Dogs: variable number of follicles, usually simple follicles but in some breeds, compound hair follicles. Normal self-cleaning mechanism removes epithelial cells, cerumen and debris in a centrifugal fashion Cerumen: mixture of secretions form sebaceous and apocrine glands – commonly called earwax. (ear wax also contains dead skin cells) #universityofsurrey 5 By MaggieLovesOrbit  What is otitis externa “Ot” refers to the ear canal; “itis” refers to inflammation; “externa” refers to outside Otitis externa = inflammation of the outer ear canal Varying degrees of severity #universityofsurrey 6 Aetiology Otitis externa can occur in any species with external auditory components. Any dermatosis can affect the external ear. Canine otitis externa is one of the most common presentations in small animal practice. Same approach can be applied to all species. Dr. R Roodt #universityofsurrey 7 Aetiology: PSPP Primary causes Will cause otitis in healthy ears Secondary causes Will cause otitis in abnormal ears – often in combination with predisposing factors Predisposing causes/factors Increase the risk for developing otitis Perpetuating causes/factors Occur as a result of otitis externa PSPP #universityofsurrey 8 Aetiology: PSPP Primary Secondary Perpetuating Predisposing Allergies Bacteria Ear canal stenosis Conformation Parasites Yeasts Ulceration Humidity Foreign Bodies Otitis media Inappropriate cleaning Immune mediated Ear cartilage mineralisation Irritant treatments Pyoderma Systemic disease Keratinisation disorder Ear neoplasia Endocrine diseases Dr. J. Gautchi #universityofsurrey 9 Aetiology: Primary causes Primary Allergy Atopic dermatitis Food allergy Contact allergy Flea allergy Parasites/ Infection Mites (Otodectes cyanotis ; Demodex; Sarcoptes; Neotrombicula autumnalis); Fleas; Ticks; Fungal infections; Virus (Equine papilloma virus) Foreign Body Grass awns; hair; dirt Immune mediated Pemphigus foliaceus, Cutaneous vasculitis, Bullous pemphigoid, DLE, drug reactions Primary keratinisation Hereditary disorders; zinc responsive dermatoses; seborrhoea, sebaceous adenitis disorder Neoplasia Squamous cell carcinomas, adenocarcinomas (aggressive tumours cause inflammation) Endocrine diseases Hypothyroidism; Hyperadrenocorticism Miscellaneous Juvenile cellulitis, trauma, actinic dermatitis #universityofsurrey 10 Aetiology: Primary causes Cats Mites Ceruminous gland hyperplasia Actinic dermatitis/ SCC Dogs Allergic dermatitis Foreign bodies Rabbits Psoroptes cunniculi #universityofsurrey 11 Aetiology: Primary causes » Cattle » Ringworm – Trichophyton sp. » Pigs » Actinic dermatitis » Horses » Aural plaques » Psoroptes equi » Melanoma #universityofsurrey 12 Vetbook.org Aetiology: Secondary causes #universityofsurrey 13 Aetiology: Predisposing causes Conformation (hairy ear canals, pendulous ears, narrow ear canals) Humidity (eg swimming, climate) Inappropriate cleaning Irritant treatments Obstructive ear disease ( eg polyps, ceruminous gland hyperplasia, benign neoplasia) #universityofsurrey 14  Aetiology: Perpetuating causes Inflammation Impaired self cleaning Epithelial hyperplasia Glandular hyperplasia Narrowed lumen Increased cerumen Ulceration and oedema of ear canal Connective tissue calcification and ossification Tympanic membrane inflammation, rupture otitis media #universityofsurrey 15 Approach to diagnosis History General clinical examination Dermatological examination Ear examination – otoscopy Cytology Culture and sensitivity Sensitivity testing controversial #universityofsurrey 16 Diagnosis: History – FIND PRIMARY CAUSE(S) History of other skin disease (atopy) Dietary history (food allergy) Medication history (drug reaction or overcleaning) Duration of disease Outdoor or indoor lifestyle? (grass seeds, other FBs) Swimming? Bathing? (humidity) Recurrence- seasonal? (allergic) Other animals or humans affected? (parasites) Other clinical signs (endocrine disease) Signs of: shaking head, scratching, head tilt, bad smell, discharge, pain when eating or when touched #universityofsurrey 17 Diagnosis: Examination PPSP Signalment (species, breed, age) PREDISPOSED? Full physical and dermatological examination PRIMARY? PREDIPOSED? Palpate external ear canal (hard, soft, pain) PERPETUATING? Examine pinna (hair loss, erythema, scaling, crusting, swelling) PPP Open mouth and check for evidence of pain PERPETUATING Examine ear canal (visual exam, digital exam and odour) PPP Otoscopic examination - (better ear first, may need sedation) inflammation, ulceration, discharge, fb’s, neoplasia, stenosis PPP #universityofsurrey 18 Diagnosis: Cytology PSPP Cytology should be performed in all cases affecting the ear canal simple, cheap and informative PRIMARY/SECONDARY Liquid paraffin slide/low power lens – to look for parasites Modified wrights stain (diff quick /rapidiff)/high power oil lens - look for yeasts and bacteria #universityofsurrey 19 Diagnosis: Culture SECONDARY Culture: Bacterial culture and sensitivity is indicated: In chronic or recurrent cases When prior antibiotic therapy has not been effective When rods have been demonstrated on cytology (Pseudomonas can present a therapeutic challenge) In cases of otitis media But: Be mindful of limitations – sensitivity in vivo may not = sensitivity in vitro AND we are treating topically – reaching much higher levels of drug where it is needed. #universityofsurrey 20 Treatment Failure to identify the PRIMARY cause is the most common reason for recurrence Identify Primary cause and treat Identify Secondary causes and treat Minimise progression of Perpetuating factors Address Predisposing factors Relieve pain and inflammation Educate May need further investigation/ongoing treatment May recur #universityofsurrey 21 Treatment Medical Specific treatment of primary disease Treatment of secondary disease (topical preferred) Antibiotics Antifungals Anti – inflammatory medication (topical or systemic) Cleaning agents Surgical Primary disease Predisposing/perpetuating factors #universityofsurrey 22 Reminder: Primary causes Primary Allergy Atopic dermatitis Food allergy Contact allergy Flea allergy Parasites/ Infection Mites (Otodectes cyanotis ; Demodex; Sarcoptes; Neotrombicula autumnalis); Fleas; Ticks; Fungal infections; Virus (Equine papilloma virus) Foreign Body Grass awns; hair; dirt Immune mediated Pemphigus foliaceus, Cutaneous vasculitis, Bullous pemphigoid, DLE, drug reactions Primary keratinisation Hereditary disorders; zinc responsive dermatoses; seborrhoea, sebaceous adenitis disorder Neoplasia Squamous cell carcinomas, adenocarcinomas (aggressive tumours cause inflammation) Endocrine diseases Hypothyroidism; Hyperadrenocorticism Miscellaneous Juvenile cellulitis, trauma, actinic dermatitis #universityofsurrey 23 Treatment: Allergy Identify allergen and avoid – or immunotherapy/desensitisation – or anti-inflammatory therapy Clean ears Treat secondary infection and inflammation Address owner expectations. Ongoing problem that is likely to require long term management. #universityofsurrey 24 Treatment: Infections Ear Mites (Otodectes, Psoroptes ) Mites can harbour on the body and re-infest. Systemic treatment is recommended. Treat all in contact animals Salamectin (avermectin) (Stronghold® – spot on) dogs and cats Ivermectin (avermectin) (Xeno ® Spot on) rabbits Imidacloprid (neonicotinoid) (Advocate®– spot on) dogs and cats Fluralaner (isoxazoline) (Bravecto ® - spot on) dogs and cats #universityofsurrey 26 Treatment: Other Foreign body Sedate or GA and remove FB Irrigate/flush ear Medication as needed – for secondary infections Immune mediated May include corticosteroids, ciclosporins – based on primary disease May need to treat secondary problems Primary keratinisation disorder Maintain microclimate – ear cleaners; may need surgery Endocrine disease – treat as required – levothyroxine, trilostane Neoplasia Surgery #universityofsurrey 27 Treatment: Inflammation and pain Corticosteroids Reduce inflammation in acute OE Limit pathological process /perpetuating causes in chronic OE Address pain – may be the ONLY treatment given for first 3 days Systemic (anti – inflammatory doses) and/or topical Potency scale: Hydrocortisone: 1 NB A new ear preparation containing Prednisolone: 5 just anti-inflammatory drugs Triamcinolone: 5 (triamcinolone acetonide) is now Dexamethasone: 25 available - Recicort® (Dechra Vet products) Betamethasone: 25 - useful for targeting OE that is not Fluocinolone: 100 caused by bacterial/fungal infection eg atopy #universityofsurrey 28 Treatment: Secondary Causes Bacteria, Yeasts Antibiotics Antifungals Considerations: Systemic vs topical? Topical preparations usually multicomponent – which to choose? Dosage of topical medication: 0.5 – 1 ml per ear – usually twice daily (check package – Easotic ® is once daily and has a pump that measures volume) Owner compliance - ear wicks - depo preparations – Osurnia ® (Elanco Animal Health) #universityofsurrey 29 Treatment: Secondary infections #universityofsurrey 30 Treatment: Secondary infections BSAVA PROTECT ME poster advises: Otitis externa: Topical treatment ONLY No authorized products if ear drums not intact Use in-house cytology to guide drug choice and prognosis If rods - Framycetin, Gentamicin, Polymyxin B If cocci – Florfenicol, Fusidic acid/framycetin/Polymyxin B/miconazole May combine with antiseptic ear cleaner Treat until cytology is negative (not until appears clinically normal) #universityofsurrey 31 Treatment: Ear cleaning WHY? Aids examination Removes wax harbouring microbes and small fb’s Breaks up BIOFILM -Improves exposure to and efficacy of topical tx’s HOW? Manual clean Flushing Irrigation #universityofsurrey 32 Treatment: Ear cleaning Manual ear cleaning Cleaning fluids most commonly contain: Ceruminolytics, surfactants and foaming agents e.g. sodium docusate Astringents or drying agents e.g. isopropyl alcohol Antimicrobial agents e.g. parachlorometaxylenol (PCMX) Honey – preparations containing honey have been researched but evidence for their benefit is currently lacking Instruct owner in use – videos available on web Use once or twice weekly Care….. Moisture, irritant, ototoxic #universityofsurrey 33 Treatment: Ear cleaning TrizEDTA Disrupts BIOFILM Damages bacterial cell walls – potentiates antimicrobials Non ototoxic Best given 20 -30 mins before other products But can be co-administered (ie may be mixed with other ear preps - off license) #universityofsurrey 34 Treatment: Ear cleaning Ear flushing May be necessary in initial OE therapy Performed under GA Visualise with video-otoscope/otoscope Using a Spruelle needle /urinary catheter/nasogastric feeding tube, flush and aspirate fluid Use sterile saline (or dilute chlorhexidine solution) Benefits Reduces microbial load Clears ear canal of debris and allows better penetration of topical drugs Affords better visualisation of ear canal – helps to ensure nothing is missed and allows assessment of the TM #universityofsurrey 35 Today’s Veterinary Practice Peer Reviewed Article #universityofsurrey 36 #universityofsurrey 37 Treatment: Future options In the future ….. Photodynamic therapy Photodynamic therapy using porphyrins as photosensitizing molecules is being investigated as an alternative therapy against microorganisms in localized infections. Organisms are sensitised by uptake of porphyrins and destroyed on exposure to white light. #universityofsurrey 38 Treatment: Perpetuating and Predisposing causes Treat perpetuating and predisposing factors as appropriate. OM -treat systemically Humidity – avoid swimming etc Inappropriate cleaning – use appropriate cleaning agents or avoid if necessary Address any underlying systemic disease Some conditions may require surgery #universityofsurrey 39 Treatment: Surgery Improved medical management has reduced the need for surgical procedures. May be considered in cases of: Excision of primary cause – neoplasia; congenital stenotic canal Management of secondary, perpetuating and predisposing factors that will not resolve with medical therapy - salvage procedure for cases of OE with irreversible changes. Surgery Lateral wall resection (LWR) Vertical canal ablation (VCA) Total ear canal ablation(TCA) and lateral bulla osteotomy TECABO #universityofsurrey 40 Treatment: Surgery LWR Improves drainage Gains access to polyps/neoplastic lesions VCA Irreversible disease of vertical canal (unlikely scenario – likely to fail) TCA Chronic end stage otitis Neoplasia (Deaf) Terry Emmerson ©Chris Little #universityofsurrey 41 In Practice 1996 18: 351-364 Follow up examination Revisit cases of OE Usually need first visit after 3 days of oral cortisone Re-evaluate 7 – 10 days once on topical treatment Continue/amend treatment until primary causes resolved or controlled and secondary disease is resolved (on cytology) Failure to identify the primary cause is the most common reason for recurrence #universityofsurrey 42 Summary of treatment Find and treat primary cause Clean and remove all debris and discharge – may need sedation or GA Identify, manage and/or treat secondary, predisposing and perpetuating causes Treat inflammation – may need to use oral meds – check up after 3 days If canal is swollen shut no meds will go in and you won’t be able to examine the canal Cortisone for 3 days will decrease swelling – re-examine and start topical drugs Draw up a long term management plan PPSP Educate the client Show them how to clean, how to put meds in Warn them of long term possibilities Arrange follow up examinations – don’t let owner decide when to return #universityofsurrey 43 Resources CVPM, S.W., RVT (2021). Treating Otitis Externa in Dogs. [online] Today’s Veterinary Practice. Available at: https://todaysveterinarypractice.com/dermatology/treating-otitis-externa- in-dogs/. Clinical Veterinary Advisor: Dogs and Cats, 3rd edition. Côté E, ed., Elsevier, St. Louis, Missouri, USA. 2020. ISBN 9780323676755 American College of Veterinary Surgeons. (n.d.). Otitis Externa. [online] Available at: https://www.acvs.org/small-animal/otitis-externa/ [Accessed 6 Nov. 2023]. Veterinary Manual. (n.d.). Otitis Externa in Animals - Ear Disorders. [online] Available at: https://www.msdvetmanual.com/ear-disorders/otitis- externa/otitis-externa-in-animals. 45