Primary seborrhea is an inherited disorder of keratinization or cornification more commonly seen in the American Cocker Spaniel, English Springer Spaniel, West Highland White Terrier, Shih Tzu and Basset Hound. It is characterized by hyperkeratotic scaling, greasy pruritic dermatitis with adherent crusts developing over the ventral trunk, ears, genitals, claws or foot pads. Associated erythema, lichenification, hyperpigmentation and excoriations are usually evident on visual examination.
With primary seborrhea, lesions usually start to develop between 12 - 18 months of age and are progressively worsen over time. Secondary overgrowth with yeast (Malassezia spp and Candida spp) and bacteria (Staphylococcus pseudintermedius) is common.
As a result of secondary bacterial and yeast overgrowth, a characteristically offensive cheesy odor may manifest and other diseases may ensue, such as alopecia, folliculitis, intertrigo, impetigo, paronychia and pyoderma.
A diagnosis is usually acquired by clinical history and findings, as well as supportive skin biopsy, skin cultures and histological examination of skin biopsies.
Histologically, two basic forms are recognized - oily seborrhea (seborrhea oleosa) and dry seborrhea (seborrhea sicca). Most dogs are affected by both.
Secondary causes of seborrhea which need to be distinguished from primary seborrhea would include sebaceous adenitis, atopy, hypothyroidism, hyperadrenocorticism, hyperestrogenism, Demodex spp, food allergy, nasal parakeratosis, zinc-responsive dermatosis, Leishmania spp, psoriasiform-lichenoid dermatosis, drug eruptions and lupus erythematosus. Treatment of secondary causes is essential to resolve the skin disorder.
Treatment is usually successful with long-term topical keratolytic shampoos and topical humectants. bacterial overgrowth syndrome usually requires an extended course of cephalexin at 30 mg/kg/day.
- Web MD
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