HORMONAL STATE AND EFFECTS OF THE USE OF AN ANTIPROGESTIN IN BITCHES WITH PYOMETRA

The pathogenic significance of progesterone in pyometra in bitches was investigated by evaluating the stages of the oestrous cycles of 369 b itches with pyometra. Concentrations of progesterone and oestradiol we re determined in 100 bitches with pyometra before ovariohysterectomy. Six bitches with pyometra with progesterone > 5 ng ml(-1) and oestradi ol < 25 pg ml(-1) were treated with the antigestagen RU 46534 (6 mg kg (-1), s.c.) twice on day 1 and once on days 2, 3 and 4; ovariohysterec tomy was performed on day 6. Six control bitches that met the same cri teria were ovariohysterectomized and uterine morphology was compared w ith that of the treated bitches. The effects of treatment were monitor ed by hormone, ultrasonographic imaging and histomorphological studies . The results confirm that pyometra may occur at any stage of the repr oductive cycle and that most animals are in the phase of dioestrus. Ut erine mass (g kg(-1) bodymass) with versus without content was not dif ferent in treated bitches and was significantly lower (P < 0.01) than in the control bitches. In all six dogs general clinical conditions im proved during the observation period; 23.5 +/- 11.1 h after the start of antiprogestin treatment a profuse, purulent vulval discharge was ob served. The effusion was nearly complete at day 6. The maximal detecta ble uterine lumen varied between 23 and 39 mm in diameter, it was no l onger detectable on day 6. Oestradiol concentrations remained constant while progesterone decreased with distinct individual variations. Mor phometrical examination of the endometrium revealed no differences bet ween groups. The data suggest that antigestagen treatment is a promisi ng approach for treatment of pyometra in bitches.