Recognizing dermatologic effects of steroids
These may occur in some steroid-sensitive patients with a single injection of steroid or orally administered steroid as soon as one to two weeks of therapy. Other super-sensitive patients may not be on oral or injectable steroids, just mere topicals, yet suffer the same dermatologic effects as if they were on orally administered steroid.
It is important to recognize the skin effects of steroids, and that they may persist for up to several months. Sometimes these skin changes may be mistaken for other diseases such as flea allergy dermatitis, hypothyroidism, bacterial pyoderma or naturally occurring Cushing's disease. Therapy involves discontinuation of the steroid-containing drug and "tincture of time" for the skin effects of the steroid to be eliminated.Glucocorticoids have several clinical effects on the skin: thinning of the epidermis and dermis resulting in a hyperkeratosis or in some patients, a fine peeling of the skin, visible vessels with thinning of the vessel walls resulting in easy bruising of the skin, atrophy of the adnexa or accompanying glands of the skin and alopecia or lack of hair regrowth because steroid puts the hair in a resting phase.
The hyperkeratosis or scaling usually is most evident on the ventral abdomen, particularly in breeds such as Maltese, Bichon Frise, Pug and Golden Retriever. These are the usual breeds we see which are most sensitive to the effects of steroids dermatologically but any breed or individual may be affected.
We all have seen examples of thinning skin with a fine peeling on the medial aspect of the pinna in a patient exposed to topical steroids. Other examples of systemic absorption of topical steroids resulting in skin changes include a Samoyed on prednisolone acetate ophthalmic solution used once daily in both eyes who became alopecic from the neck down, and a Pug on steroid-containing ear drops who developed clinical signs of Cushing's disease, yet all blood tests came back normal.
It is important to remember that an ACTH stimulation test can differentiate between iatrogenic Cushing's disease and naturally occurring Cushing's disease, but in some patients showing dermatological side effects of steroids the ACTH stimulation test is completely normal. It is the patient's history of steroid use and their clinical appearance (along with a skin biopsy if desired) that confirm the diagnosis.