Histologic changes in ovary, uterus, vagina, and mammary gland of mature beagle dogs treated with the SERM idoxifene.

Background: Idoxifene is a selective estrogen receptor modulator similar to tamoxifen but is no longer in pharmaceutical development due to adverse genitourinary effects in the clinic. Histologic observations of the reproductive system and mammary glands are presented from female dogs treated with idoxifene for up to 12 months.

Methods: Studies were conducted as part of regulatory requirements to support clinical development.