Ear Margin Dermatosis

Also known as: Canine ear margin seborrhea

Introduction

Canine ear margin dermatosis is a relatively common abnormality in cornification, with lesions confined to the margins of the pinnae.

It shows marked predilection for the Dachshund and a hereditary basis is suspected. It is also present in other breeds of dogs with pendulous ears and it may be a clinical feature of hypothyroidism.

Age and sex predilections have not been noted.

Clinical Signs

Pruritus is rarely seen, in contrast with the early signs of sarcoptic mange.

There is variable alopecia, scaling, crusting and keratinous debris at the pinnal margins. The exudate can be greasy or waxy, tenacious to exfoliative and varies from yellow to brown.

A waxy seborrheic odour is often present and keratin mats the remaining hair.

Diagnosis

Skin scrapings might rule in scabies, which is a possible differential diagnosis.

Histopathology can rule out vasculitis and provide a definitive diagnosis.

Canine ear margin dermatosis is characterised by severe hyperkeratosis, predominantly follicular. Keratin distends the follicular ostia and surrounds the protruding hair shafts to produce follicular fronds. There is usually also a variable inflammatory infiltrate including lymphocytes, plasma cells, macrophages and neutrophils.

Treatment

It is an incurable condition that can be controlled through the use of antiseborrheic treatments such as benzoyl peroxide and sulfur salicylic acid shampoos as well as moisturisers.

Hard areas can be soaked in warm water, and the hair can be clipped before any shampoo is applied.

Shampooing should be performed every 24 to 48 hours until the debris is completely removed, then the frequency can be reduced to an as-needed basis.

Inflamed ears might also benefit from a topical corticosteroid cream such as 1% hydrocortisone.

In severe cases, surgical debridement might be necessary to stop the development of fissuring, and laser surgery is also helpful.

Ear Margin Dermatosis Learning Resources
Flashcards Test your knowledge using flashcard type questions	Small Animal Dermatology Q&A 20

References

Schaer, M. (2010) Clinical medicine of the dog and cat Manson Publishing

Muller, G. (2001) Small animal dermatology Elsevier Health Sciences

Gross, T. L. (2005) Skin diseases of the dog and cat: clinical and histopathologic diagnosis Wiley-Blackwell

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