Department of General Pathology, Institute of Biological Sciences, Federal University of Minas Gerais, Brazil.
Acta Vet Scand. 2010 Dec 22;52(1):67. doi: 10.1186/1751-0147-52-67.
Mammary tumors are among the most frequent neoplasms in female dogs, but the strategies employed in animal treatment are limited. In human medicine, hormone manipulation is used in cancer therapy. Tamoxifen citrate is a selective inhibitor of oestrogen receptors and exerts a potent anti-oestrogen effect on the mammary gland. The aim of this study was to evaluate the adverse effects when exposing healthy female dogs to tamoxifen.
Tamoxifen was administered for 120 days at a dose of 0.5 or 0.8 mg/kg/day to either intact or spayed female dogs. The effects were assessed through clinical examination, haematology, serum biochemistry, ophthalmology and bone marrow aspirate examination. Ovariohysterectomy was performed and the uterus examined by histopathology.
Vulva oedema and purulent vaginal discharge developed with 10 days of tamoxifen exposure in all groups. Pyometra was diagnosed after around 90 days of exposure in intact females with frequencies increasing during the following 30 days of exposure. Up to 50% of dogs within the groups developed retinitis but none of the dogs had signs of reduced visual acuity. The prevalence of retinitis in each group was similar after 120 days of exposure. Haematological, biochemical and bone marrow changes were not observed. Due to the high risk of developing pyometra after prolonged exposure to tamoxifen, only spayed animals should be given this medication.
A dose of 0.8 mg tamoxifen/kg body weight/day is recommended when treating tamoxifen-responsive canine mammary tumors. Due to the high risk of developing pyometra, ovariohysterectomy is recommended.
乳腺肿瘤是雌性犬中最常见的肿瘤之一，但动物治疗中采用的策略有限。在人类医学中，激素操纵被用于癌症治疗。枸橼酸他莫昔芬是雌激素受体的选择性抑制剂，对乳腺具有强烈的抗雌激素作用。本研究旨在评估健康雌性犬暴露于他莫昔芬时的不良反应。
以 0.5 或 0.8mg/kg/天的剂量给未去势或已去势的雌性犬连续 120 天给予他莫昔芬。通过临床检查、血液学、血清生化学、眼科和骨髓抽吸检查来评估效果。进行卵巢子宫切除术，并通过组织病理学检查子宫。
所有组的犬在暴露于他莫昔芬 10 天后均出现外阴水肿和脓性阴道分泌物。在未去势的雌性犬中，在暴露 90 天后诊断为子宫积脓，在随后的 30 天暴露中，发病率增加。高达 50%的犬出现视网膜病变，但没有犬的视力明显下降。在 120 天后，每组中视网膜病变的患病率相似。未观察到血液学、生化和骨髓变化。由于长时间暴露于他莫昔芬后，犬发生子宫积脓的风险很高，因此仅应给予已去势的动物这种药物。
当治疗对他莫昔芬有反应的犬乳腺肿瘤时，建议使用 0.8mg/kg 体重/天的他莫昔芬剂量。由于发生子宫积脓的风险很高，建议进行卵巢子宫切除术。
