DYNAMICS OF HEMOSTASIS DURING THE ESTROUS-CYCLE AND PREGNANCY IN BITCHES

The blood coagulation status was studied in 31 bitches of different br eeds during 33 oestrous cycles and during nine pregnancies. Two other bitches were ovariohysterectomized and received subcutaneous injection s of oestradiol benzoate for 7 consecutive days. blood samples were ta ken in early and late follicular phases, at ovulation, at day I after the end of oestrus as determined by cytology, at days 30, 60, 90 and 1 20 of metoestrus and in anoestrus. The samples were analysed for the c oncentrations of fibrinogen, fibrin(ogen) degradation products, as wel l as for the prothrombin time, the activated partial thromboplastin ti me, the antithrombin III activity, the number of platelets and the hae matocrit. In other blood plasma samples the concentrations of oestradi ol and progesterone were measured. In the two bitches that were ovario hysterectomized and received subcutaneous injections of oestradiol ben zoate for 7 consecutive days, the coagulation parameters and hormones were examined in blood samples collected at appropriate terms and time intervals as in intact-dogs. The significantly increased concentratio ns of fibrinogen and fibrin(ogen) degradation products, the large numb er of platelets and the decreased antithrombin LII activity observed d uring the luteal phase of the nonpregnant and pregnant bitches are att ributed to direct or indirect effects of the high peripheral progester one concentrations. In the mid-luteal phase (day 30) this activation w as more distinct during pregnancy than in the nonpregnant dogs presuma bly owing to additional effects of local processes in the uteroplacent al area. Influences of high concentrations of oestradiol were not obse rved either during the follicular phase of the intact bitches or after oestradiol benzoate administration in the ovariohysterectomized dogs.