Help I realize it's late in the season but we have nice weather in CO for awhile. We are trying to breed a 12 year old warmblood mare who had a foal 4 years ago. She was pregnant after last breeding despite never having had any uterine edema, but when checked she was resorbing the pregnancy and had a CL present. She also had a 3.3 follicle, no edema. So we waited three days to re-ultrasound. She had ovulated. Now we are short cycling her and planning to breed again. Any ideas what is going on here? thanks Erica
Posted on Thursday, September 01, 2011 - 12:05 pm:
The first point to consider is that some mares will produce and ovulate follicles in the face of elevated levels of progesterone - i.e. during diestrus when they are not in estrus ("heat"). Consequently, what you might be seeing is a diestrus follicle developing and ovulating. It is possible to achieve a pregnancy on these diestrus follicles, but there is a significant risk of creating an unrelenting inflammatory response in the uterus upon introduction of the semen through the closed cervix, so it is generally considered to be preferable to avoid diestrus breeding like the plague!
Uterine edema is linked to estrogen levels in that when progesterone levels are <1 ng/ml and the mare is in estrus with a developing follicle, the edema will be pronounced. The fact that progesterone levels are required to be <1 ng/ml (i.e. the mare is in estrus or anestrus) again suggests that you may have been observing a diestrus follicle and ovulation.
Follicular diameter and ovulation alone are not a reliable indicator of the correct time to breed! I would suggest following them are more closely with ultrasound. You might also consider the use of P&E or one of the other reliable timing agents described in that linked article.
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