Hair Loss & Hormones

Estrogen is a hair growth-inhibitor in dogs and is commonly associated with Sertoli cell tumor skin disease and female hyperestrogenism. Five dogs (3 in the same household) with short, fine hair coats developed progressive noninflammatory alopecia. Routine physical examination and diagnostic testing did not reveal an underlying cause. Skin biopsies revealed changes typical of noninflammatory alopecic disorders (eg, follicular atrophy, hair follicles predominantly in the kenogen or telogen stage). Detailed questioning of the owners revealed that all used transdermal estrogen gels and that the dogs had close contact with the owners, including sleeping in the owners’ beds, before the onset of hair loss. An elevated estrogen concentration was identified in 1 of 2 dogs tested. Alopecia almost completely resolved after contact with the gel was stopped.

Commentary

Noninflammatory alopecia of dogs can be a frustrating disorder for small animal practitioners. It is easy to forget the diagnostic algorithm for hair loss without itch or redness or rash because allergic and parasitic causes of skin disease are vastly more common. Patient exposure to medications used by people in the household might not be among the questions typically asked when gathering history. In cases of noninflammatory alopecia in dogs, the possibility of exposure to hormone-replacement therapies should be questioned along with the examination and diagnostic tests described in this case series.—Liz Layne, DVM