Thirteen-weeks subcutaneous treatment with oestradiol or an oestradiol/progesterone combination in beagle bitches.

High doses of oestradiol (150 micrograms/kg) or an oestradiol/progesterone combination (150 micrograms/kg oestradiol plus 6.25 mg/kg progesterone) were administered subcutaneously on alternate days to immature ovariectomised and mature intact female Beagle dogs for 13 weeks. The effects of hormonal treatment on different parameters were studied. The results revealed severe anaemia (mainly at week 3) and the blood films showed morphological indication of blood loss and abnormal erythrogenesis. Neutrophil leucocytosis and non-progressive thrombocytopenia were also observed. Treatment with oestradiol alone induced changes in the endometrial stroma and myometrium, whereas treatment with the oestradiol/progesterone combination induced cystic endometrial hyperplasia. The pituitary glands of the dogs treated with oestradiol alone had a slight increase in the number of ACTH cells. These cells and STH cells showed cytological changes indicative of accelerated secretory activity; the PRL and gonadotropin-producing cells were not affected significantly. The oestradiol/progesterone combination increased the number of ACTH and PRL cells. These cells as well as STH cells exhibited several cytological criteria typical of a pituitary cell with accelerated activity; the gondadotropin-producing cells showed involutionary changes. The mammary glands of oestradiol-treated dogs showed stromal and ductal cell proliferation; whereas the oestradiol/progesterone combination induced secretory epithelial cell proliferation in addition to stromal and ductal cell proliferation.