[1] Univ Calif San Francisco, Dept Vet Affairs, San Francisco, CA 94143 USA
[2] Univ Calif San Francisco, Vet Affairs Med Ctr, San Francisco, CA 94143 USA
[3] Univ Calif San Francisco, Dept Dermatol, San Francisco, CA 94143 USA
[4] Rhode Isl Hosp, Dermatoepidemiol Unit, Providence Vet Affairs Med Ctr, Providence, RI USA
[5] Rhode Isl Hosp, Dept Dermatol, Providence, RI USA
[6] Brown Univ, Providence, RI 02912 USA