Systemic and Histopathologic Changes in Beagle Dogs After Chronic Daily Oral Administration of Synthetic (Ethinyl Estradiol) or Natural (Estradiol) Estrogens, with Special Reference to the Kidney and Thyroid

Raloxifene effects on thyroid gland morphology in ovariectomized rats

“…The general appearance of thyroid glands of Ovx þ raloxifene and Ovx þ estrogen-treated animals is characteristic of cell proliferation and architectural distortion, which are similar to those produced by the action of thyroid stimulating hormone. A similar result was found in a previous experiment with dogs, after a long-term administration of estrogen, in which intense abnormal cell proliferation and squamous metaplasia of thyroid follicles was observed (21). In fact, some studies provided evidence that at least in females, estrogen may play a role in thyroid carcinogenesis (22,23), and that ovariectomy can decrease the incidence of drug-induced thyroid carcinogenesis, whereas estrogen administration reverses these effects and increases the occurrence of tumors in female rats (24).…”

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

“…Mesothelial hyperplasia in the ovary has previously been documented in dogs given various estrogenic compounds (Heywood and Wadsworth, 1981;Zayed et al, 1998). In rodents, idoxifene caused follicular atresia and a reduction of corpora lutea in studies up to 6 months in duration (unpublished observation).…”

“…Adverse hematologic effects, including anemia and leucopenia thrombocytopenia, which often limit the duration of hormonal studies in dogs, were not observed with idoxifene (Heywood and Wadsworth, 1981;Hart, 1990;Zayed et al, 1998). Reproductive and mammary gland tissues changes seen in female dogs given idoxifene for up to 12 months were similar to those reported for tamoxifen and can be attributed to estrogen agonist or antagonist activity when compared to findings during the normal estrus cycle or associated with estrogen treatments (Table 4).…”

“…In dog, initial mammary gland ductules start to proliferate in proestrus but major glandular development occurs later during the cycle under the influence of progesterone, locally produced growth hormone and prolactin (Rehm et al, 2007). Consistent with a selective estrogenic effect, ductal hyperplasia, but not alveolar proliferation, was observed with estradiol, ethinyl estradiol, and stilbestrol (Heywood and Wadsworth, 1981;Zayed et al, 1998). Quinestrol has been reported to induce considerable glandular mammary proliferation.…”

Simulation of Incomplete Obstructive Uropathy in Rats by Injecting an Artificial Calculus into the Bladder

“…The majority of the known experimental models reproduce complete obstruction of the urinary tract [4,13]. Incomplete obstructive uropathy model created by hormonal stimulation of the prostate [11] distorts the picture of renal parenchymatous lesions, is diffi cult to reproduce, and has to be created in large animals.…”