Sadly, one of my mares aborted at 3 months last week. I'd never seen a small equine embryo except in pics - so thought some of you might find it interesting.
I should have put a ruler beside it for size - but it's in a 5 kg Horselyx container which will give you an idea. The hooves can be clearly seen - already with little spongy pads - but the leg bones aren't calcified and are quite 'bendy'.
It was a sad discovery - but at least I know there will be no foal from her next year. As to cause, too soon for EHV. And nothing else 'fits'. My vet actually missed this pregnancy at the 14 day scan - first time he's EVER done that (at least with my mares!) When she didn't come into season by 21 days, we scanned again and sure enough, there it was - but he made a note at the time that it was abnormally high up - whether that was the cause -