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

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).

  • 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.

  • 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 –

  • Bilaterally symmetric – feature of endocrine disease.

  • Focal / broken hair around – trauma (pruritus) and infectious disease.

  • 1⁰ and 2⁰ skin lesions. Pinnal deformities, hyperplastic tissue in the canal.

• Ear exudate:

  • Yellow-green w/strong odder - Pseudomonas or proteus bacteria.

  • Brownish fluid-like – staph. or strep. Infection.

  • 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

  • 1^st use a Ceruminolytic = Docusate Sodium (DSS).

  • 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

2. Otitis Media/Interna

Etiology

• Bacteria Staph. Intermedius, Pseudomonas spp

• Yeast

• Congenital palatine defects 2⁰ Cleft palate

• Primary sectretory otitis media Cavaliers

• Neoplasia and polyps O. Media

• Cholesteatomas Abnormal growths of the epithelium within the middle ear. Consist of strat. Squam. Epithelium, inflammatory cells and ceruminous debris. Can be congenital or 2⁰ to chronic O. Media

2a. Otitis Media

= inflammation of middle ear TM, bulla tympanica, auditory ossicles and auditory tube

• Commonly an extension of otitis externa through a ruptured TM

• Aspiration of pharyngeal contents up auditory tube (e.g. Sequela to URT infection in cats)

• Haematogenous spread.

• If TM is ruptured on examination, assume otitis media exists

• Important perpetuating cause of recurrent otitis externa

Clinical Signs

• Often reflect concurrent otitis externa (Discharge from ear, pawing/rubbing affected ear, headshaking, pain).

Specific for Otitis media

• Facial nerve paresis Drooping of or cannot move ear or lip, drooling, decreased/absent palpebral reflex

• Horners Syndrome injury to sympathetic nerves which pass near middle ear Ptosis, miosis, enophthalmus, protrusion of 3^rd eyelid (can see KCS sometimes)

• Pain on palpation of bullae

• Bulging, opaque or ruptured TM

2b. Otitis Interna

• Inflammation of the inner ear structures Cochlea, vestibule, semicircular canals

• Usually a direct extension from existing otitis media

• Can also be haematogenous spread

Clinical Signs

• As for otitis media but may also have neurological signs

• O. Interna may account fo 50% of all cases of acute peripheral vestibular diseases

• Head tilt, ataxia, horizontal or rotary nystagmus, circling or falling toward the side of the lesion, or ipsilateral nystagmus. The fast phase of nystagmus is usually away from the side of the lesion. Occasionally, animals...

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