I read about going through the flank with a long needle to reduce a twin. I'd try that once before terminating the entire pregnancy.
The success rate for that procedure is around 50%. I tried that on a mare a couple of years ago at UC Davis, unsuccessfully. The best I can say about the whole thing is it is educational. If I had it to do all over again, and I really, really wanted a foal from the mare the following year, I would abort the pregnancy no later than 30ish days, and rebreed.
Surprisingly, the cost of the procedure wasn't terrible, although (of course) it was more than originally thought because they tried on two separate occasions. I was where you are; I wasn't going to rebreed anyway because it was getting late in the year, so I thought I would try for a natural reduction, then the "experimental" one if that didn't work, and terminating the pregnancy if I had to. It can be done at home up to about 100 days, although it wasn't very nice for the mare.
My adorable spotted Shetland is in foal to a buckskin mini . . . doubly so!
I'm not freaking out. She's had four foals, easy-peasy, never been scanned before, but no losses that would indicate previous prolonged twinning.
So we're just going to wait and see if Mother Nature works things out, and if not we'll terminate and maybe try again next year. Getting a little late in the season to try again.
She was in heat for nearly 10 days and stood for the stallion SIX times, the hussy . . . does this correlate at all with a likelihood of twinning or double ovulation?
Good luck on all this.
Next time have your mare ultrasounded and give hcg so you only have to breed once (will decrease chances) and check her at 16-20 days post ovulation -- then you can pinch without losing the whole pregnancy.
The cost of 2 extra ultrasound will be far less than waiting another year...
Yes, well, life kind of got in the way of the day-15 ultrasound this time. The last two mares I bred were scanned with high anxiety and hand-wringing, everything to the letter, on day 15 and open . . . this one where the whole schedule was off-kilter, and she's got TWO.