One user wrote in to H&C for help on getting their mare in foal:
“I sent my mare off to stud to be covered, and not only is she not pregnant, but she has not come into season once since being there. They've given her two of the "jabs" which apparently are designed to bring a mare into season and they still haven't worked, so myself, the stud owner and the vets are at a loss as to what is causing it.
They checked to see if there was a marble in her uterus, which there isn't. The only thing the stud owner said to me recently which made me worry was that she said the horse was fine in herself, but just not flourishing as well as some of the other mares she's got.
If you have any advice I would greatly appreciate it.”
Breeding expert Ann Egan replies:
I would suspect that it is likely that your mare is experiencing "silent heat", that is that ovulation is occurring without the signs of oestrus. I am assuming that by "jabs" you mean that the mare has had prostaglandin injections? If that is indeed the case, the incidence of silent heat occurring after such shots is about 15%. Because of this, it can be easy to miss the signs of "coming in to season" if the mare is not being teased and follicles are not being monitored after these injections are given. Just for a point of reference, ovulation generally occurs about seven to twelve days after you stop the progesterone treatment.
Here at North Point Farm, we rely more on technology and less on mother nature to make sure that we are following our mares during breeding season, that is to say that we ultrasound mares on a daily or every other day basis. In some cases, we may use our stallion to confirm what we are seeing or what we are not seeing as the case may be. By using the ultrasound, we can easily see and measure follicle development and ovulation for optimum breeding times. You don't say if the stud farm is using ultrasound but I would encourage you, in this situation, to make use of this technology if at all possible.
Another possible cause for what you are seeing could be prolonged diestrus where the CL doesn’t regress and which can persist for several months. The cause of this is failure of normal luteolysis, thought to be due to a deficiency of prostaglandin release from uterus. I wouldn't suspect this is the case with your mare because you refer to the "jabs" to bring her in to season which I am assuming are prostaglandin injections and, if the mare was experiencing prolonged diestrus, the treatment would be prostaglandin injections. I mention this merely as something else to be considered.
As for the mare not being herself, some mares get homesick just as some people do. If she is being well cared for, and is not off her grain, I wouldn't worry if she seems a bit sad to be away from you. You might try visiting with her if possible or asking the stud farm to spend a bit more time with her, brushing or hand walking her if they are agreeable. Some mares also need the emotional support of other mares so if she can graze nearby or share a fence line with other broodmares safely, that may help her disposition. I wouldn't however, expect that this is the problem with her being bred.
If this were my mare, my money would be on the "silent heat" scenario and I would have an ultrasound (or several in order to follow her) done.
Thanks for the question and the best of luck to you!