Peripheral plasma concentrations of progesterone in the bitch with pyometra

In the present study, 35 bitches (various breeds and ages) with pyometra were involved. Blood sampling (jugular vein) took place every day between examination and hysterectomy. All the bitches examined after 60 days post-oestrus had a low progesterone concentration (about 1 ng/ml). Along the 27 bitches observed before that time, 22 had a high mean level (about 8 ng/ml). By contrast 5 of them had low levels. As a whole these results suggest that: 1) There is no evidence of an essentially high or prolonged progesterone secretion in pyometra. 2) Luteolysis occuring normally about 60 days post ovulation is not postponed by this affection and 3) In some animals, early luteolysis seems to occur. Therefore it cannot be concluded that progesterone has an indispensalbe role in polymetra.