The other five problems have to do with the bitch herself, and progesterone testing the DAY of ovulation is the day her progesterone goes above 5 nanograms. Even though she has this three week-plus heat cycle, there is a three to four day window we have to hit that varies from bitch to bitch. With progesterone testing, we can be sure the semen is put in at the proper time no matter what type of insemination method we are using.
In the bitch, the semen is pumped up into the uterus....so outside ties... poorly done AIs... that don't deposit the semen in the cervix, which is located in the abdomen above the bladder, prevent sement from being drawn up into the uterus.
As bitches age, they get cysts within their uterus which can obstruct the pathway - a good reason in an older bitch for considering a surgical insemination.
Conception takes place in the Fallopian Tubes regardless of the method of insemination.
An older bitch is any bitch over 5, by the way; several of you asked.
The fertilized eggs are then released into the uterus, but don't implant until day 17-18 after ovulation. So if there are uterine lining problems, we either don't have implantation OR...the placenta, which actually grows into the lining of the uterus, can't grow or be maintained, and the puppies are reabsorbed. It will develop as the night goes on, how to detect some of these problems.
When a bitch ovulates, whether we breed her, don't breed her, or pretend she's not in season, the progesterone HAMMERS the uterine lining for sixty-plus days.
The progesterone level is NOT affected by pregnancy. In the cow for example, if the uterus does not get communication from the fertilized egg by day 16, the whole process starts over again. In the bitch, you don't have that luxury.
Even though the bitch's body produces the progesterone, the progesterone is inflammatory to the uterine lining, so that after a heat cycle, the bitch's uterus is never as healthy as it was before the heat cycle. So we go from a normal uterus... and this start's with the first cycle of her life...to an endometritis to endometrial hyperplasia, which some of you have been asking about - this is when the uterus starts to thicken and we start to get bubbles in the lining of the uterus - these changes affect the uterine lining so much so that eventually the uterus cannot control the bacteria, and the ultimate end stage is pyometritis.
So, in the bitch... So breeding back to back... or even back to back to back to back....this is WHY it's such a crime we don't have Cheque drops on the market now, to preserve the bitch's uterine lining.