Small Animal Dermatology Q&A 19

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A 2-year-old cocker spaniel dog was presented for recurrent otitis externa. The opening to the external ear canal could not be found, and the vertical ear canal was hard upon palpation. Dermatological examination was normal except for nasal digital hyperkeratosis and mild scaling on the skin.

Question	Answer		Article
What common clinical syndrome is being depicted?	Proliferative otitis externa.		[[|Link to Article]]
What is the most likely underlying cause in this patient?	The most likely cause in a 2-year-old cocker spaniel dog is a primary disorder of keratinization. The nasal digital hyperkeratosis and scaling in the hair coat are also compatible with a disorder of keratinization.		[[|Link to Article]]
How is this condition treated?	There are several treatment options, and the goal of therapy is to reestablish an open vertical and horizontal ear canal. Palpation of the ear canal may be all that is required to determine that the canal is calcified. In other cases, a skull radiograph should be taken to determine if there is calcification in the soft tissue of the ear canal, and/or to determine if the proliferative otitis is limited to the pinnae. If no calcification is present, systemic glucocorticoid therapy (2.2 mg/kg PO q24h for 3–4 weeks) may shrink this tissue and reestablish an open ear canal. If the ear tissue responds to systemic glucocorticoids, topical daily glucocorticoid otic preparations can be used to maintain the patency of the ear canal, especially in dogs with mild proliferative otitis. Alternatively, oral cyclosporin A (5 mg/kg q12h) for 12 weeks may be another option. If the proliferative tissue is limited to the pinnae, laser therapy can be used to remove the polyp-like tissue. If there is no response to glucocorticoid therapy or if calcification of the ear canal is present, the ears are considered ‘end stage’ and total ear canal ablation is the best surgical option. It is important for owners to understand that dogs with proliferative otitis externa due to a disorder of keratinization will be predisposed to further episodes and may eventually require surgery. Although the owners are focused on the ears, it is important that they understand the dog’s generalized seborrhea will need to be treated and will require life-long therapy. Frequent bathing (2–3 times a week) is needed in many cases to treat dogs with severe primary disorders of keratinization.		[[|Link to Article]]