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Ear Diseases (Otitis Externa Media Interna) And Skin Adnexes Notes

Veterinary Medicine Notes > Small Animal Internal Disease - Skin Notes

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6. Ear Diseases (Otitis Externa, Media and Interna) and Skin Adnexes EAR DISEASES

1. Otitis Externa An acute or chronic inflammation of the epithelium of the external ear canal. Pinna to tympanic membrane Otitis Externa is often a clinical manifestation of a generalized dermatological condition Etiology The causes of otitis externa have been grouped into 3 areas; often all 3 factors are involved, but each category must be identified and addressed separately. In this way a more accurate prognosis can be provided, a specific and safe therapeutic plan formulated, and the best possible outcome from treatment assured. Primary factors - disease conditions that directly cause the otitis.

* Parasites - Otodectes cynotis (ear mites), Sacroptes scabiei, Notoedres cati, Demodex canis, Cheyletiella spp, and Eutrombicula spp (chiggers). o Ear mites have been reported to account for up to 50% of cases of otitis externa in felines and 5-10% of cases in canines. o Otobius megnini (the spinose ear tick) mainly in dogs.

* Foreign bodies - grass awn (foxtails), concreted wax, medications.

* Tumors - cerumin gland adenoma, inflammatory polyps.

* Hypersensitivity - atopic dermatitis, food allergies, contact dermatitis.

* Keratinization disorders - Seborrhea, hypothyroidism, hyperadrenocorticism

* Autoimmune Diseases - Relatively rare cause - e.g. pemphigus Predisposing factors (Don no initiate otitis externa) Facilitate inflammation by promoting and environment that increases the risk of devp of the condition

* Confirmation of the ear canal

* Moisture in ear canal (dogs that swim)

* Hairy ears/Floppy ears

* Breed - Shar-Pei have stenotic ear canals

* Obstructive disease - polyps, neoplasia

* Iatrogenic ear trauma - unnecessary hair removal and cleaning with cotton buds

* Systemic disease. Perpetuating factors - Sustain and aggravate the inflammatory process Includes occlusion if the canal which inhibits adequate drying or proper medication of the canal Bacteria

* Staphylococcus intermedius - most common in dogs &cats.

* Proteus mirabilis.

* Pseudomonas aeruginosa.

* Pasturella.

* E.Coli. Yeast

* Malassezia pachydermatis but other fungi may also appear.

Clinical Signs

* Clinical signs are caused primarily by pruritus and pain which lead to self trauma.

* Head shaking, scratching & rubbing the ears and other behavioral changes.

* Erythema, edema, bleeding.

* Alopecia - o Bilaterally symmetric - feature of endocrine disease. o Focal / broken hair around - trauma (pruritus) and infectious disease. o 10 and 20 skin lesions. Pinnal deformities, hyperplastic tissue in the canal.

* Ear exudate: o Yellow-green w/strong odder - Pseudomonas or proteus bacteria. o Brownish fluid-like - staph. or strep. Infection. o Thick, waxy, brown-black - Malassezia or Otodectes cynotis. Diagnosis History - evidence of any dermatology problems, parasites, allergies, environment, response to previous therapy or any behavioral changes. Physical examination -

* Pinnae and periauricular area inspected for evidence of self-trauma, erythema,masses, ticks and discharges Otoscopic examination

* Evaluate size/width of ear canal and state of epithelium.

* Look for: foreign bodies, polyps, tumors, exudate hair or parasites.

* Last evaluate the tympanic membrane (if ruptured - do NOT administrate any drugs to ear canal). Cytologic examination - Smear- Stain for bacteria and yeast Skin scrapings - to check for mites Biopsy - taken from abnormal masses. Treatment

* Cleaning o 1st use a Ceruminolytic = Docusate Sodium (DSS). o Then povidine-iodine or chlorhexidine, Use saline if tympanic membrane (TM) is ruptured. 2X daily

* Topical anti-inflammatory - Betamethasone (otomax)

* Topical Glucocorticoids - decreasing pruritus, exudation, swelling, and proliferative changes e.g dexamethasone - Short term only (no more than 10 days)

* Topical Antifungal - Miconazole, clotrimazole, nystatin, and thiabendazole (systemic antifungals better

* Topical ATB - Enrofloxacin, Polymixin B, Chloramphenicol, Gentamycin/Neomycin (Ototoxic if TM is ruptured - If TM is ruptured or in chronic recurrent problems, middle or inner ear infections

* Parasites - Ivermectin

* Surgery - For recurrent issues - LECR, VECA, TECA

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