Seborrhea is often used as a general term for dry, flaky skin that is often referred to as dandruff. In a strict medical sense, however, seborrhea is a chronic inflammatory disease of the skin characterized by the accumulation of flakes, scales and yellowish or grayish crusty plaques. Greasiness, itchiness and secondary infections may be a factor as well. Dogs are most commonly affected.
The canine skin secretes oil and even sweat but it should never appear greasy or oily. In normal dog skin, some amount of flakiness is common, but the exfoliated cells that cause this flakiness should be hard to find under a microscope and seldom (if ever) adhered to the skin or to the hair shafts.
In the case of seborrhea, the skin produces too many of its superficial epidermal cells (it renews every week instead of every three weeks). This acceleration in the rate of cell production, the primary feature of seborrhea, leads to an increase in sebaceous gland turnover rate, too.
Any dog can acquire a dry form of seborrhea called seborrhea sicca. These dogs will have scaly skin over their trunk and possibly in their axillae (armpits). They may have itchy, inflamed and infected skin.
The American Cocker Spaniel, however, is predisposed to a form of seborrhea called seborrhea oleosa. This form, also referred to as primary seborrhea in the Cocker Spaniel, leads to oily, smelly, itchy, inflamed and infected skin.
But, as with seborrhea sicca, any dog can suffer seborrhea oleosa secondary to other skin conditions, including allergic skin disease, hypothyroidism and Cushings disease, among others. Collectively, any non-primary forms of seborrhea are referred to as secondary seborrhea.
Dogs affected by primary seborrhea can develop secondary skin infections. The main microbes involved with seborrhea include Staphylococcus and Malassezia on the skin and in the ear canal, which can increase the signs of itchiness and unpleasant odor.
Symptoms and Identification
Seborrhea is characterized by the signs described above. It can be diagnosed via the following techniques:
Cytology: Microscopic evaluation of the skin may be achieved by pressing a glass slide onto its surface (referred to as an impression smear). The loose cells, scales, microbes and even hair shafts will adhere to the slide, thereby facilitating the diagnosis of seborrhea.
Biopsy: Diagnosis can be difficult to achieve in the case of the primary seborrea that afflicts American Cocker Spaniels. That's because seborrhea is more commonly seen secondary to other causes -- even in the Cocker. That's why the best diagnostic tool is a skin biopsy. A rapid anesthetic procedure is typically required.
As described above, all breeds of dogs may suffer from seborrhea, but the American Cocker Spaniel is predisposed to a form called primary seborrhea. The mode of inheritance is not yet known.
Seborrhea is considered a highly treatable (if frustrating) dermatological condition. Treating any underlying diseases is the standard approach for non-hereditary forms of the disease, but we have to treat the symptoms along the way if we're to achieve comfort as rapidly as possible. In cases of primary seborrhea, a symptomatic approach is the mainstay of treatment.
Treatment of the symptoms typically involves antibiotics for the bacterial skin infection and anti-fungal medication for the yeast microbes. Oral and topical medications are requires if the skin infections are severe.
Topical therapy includes shampooing (usually every three days to five days). Soap-free shampoos containing sulfur-based compounds and salicylic acid are recommended. In cases where oiliness is present, benzoyl peroxide or tar-based shampoos may be necessary. Moisturizing, dog skin-specific formulas are recommended.
Oral therapy is sometimes needed for severe cases. These may include oral fatty-acid supplements your veterinarian can recommend. Oral retinoic acid (or high doses of Vitamin A) may also be recommended. Accutane (isotretinoin), used for human acne, is a newer therapy that may be appropriate. Another acne medication, Soriatane (acitretin), may appropriate as well. In some cases, corticosteroids or cyclosporine may be recommended to help mitigate inflammation.
The veterinary cost of seborrhea is largely relegated to the diagnostics and treatments listed above. These are not insubstantial. Diagnosis can cost up to $1,500 if a dermatologist is employed -- and even more in cases where several illnesses are potentially in play (such as allergic skin disease).
Treatment with topical shampoos and oral medications can really add up as well, especially for larger dogs. Monthly, these treatments may reach into the low hundreds for some afflicted patients, particularly if generic medications are unavailable.
There is no known means of prevention for seborrhea except for careful breeding of lines of dogs with a known genetic predisposition to primary seborrhea.
Campbell, K.L. 1997. Diagnosis and management of keratinization disorders in dogs. ACVIM - Proceedings of the 15th Annual Vet. Medical Forum. pp 220-222.
Merck Veterinary Manual: http://www.merckmanuals.com/vet/integumentary_system/seborrhea/overview_of_seborrhea.html
Power, H.T., Ihrke, P.J. 1995. The use of synthetic retinoids in veterinary medicine. In J.D. Bonagura and R.W. Kirk (eds.) Kirk's Current Veterinary Therapy XII Small Animal Practice. p585-590. W.B. Saunders Co., Toronto.
Scott, D.W., Miller, W.H., Griffin, C.E. 1995. Muller and Kirk's Small Animal Dermatology. pp 737-743 W.B. Saunders Co., Toronto. This has a practical and detailed section on clinical management.