Hi, I'm Dr. Jill. Are you able to identify where the blood you've seen between her udders is coming from? Any signs of discharge from her vulva?
There are a number of different causes for where blood could be coming from. She could have irritation or a skin infection between her udders causing local bleeding, she could have ulcers in her gastrointestinal tract causing the darker appearing feces (usually they look black and tarry with blood in them), and she could be having a later term abortion with blood and fluid coming from her vulva. On a brighter note, though, there are also blood vessels that develop with pregnancy in their vulvar vestibular area that can burst and cause bright red blood to come from the vulva, but they are only superficial vessels and cause no further problems.
If she's still eating and drinking well (with the baby taking up so much abdominal space, I wouldn't be surprised if she's only able to eat small amounts at a time), you can opt to wait and see what happens. Or you can have your veterinarian out to examine her, palpate the fetus to make sure it's still doing well, and possibly ultrasound the fetus and placenta, and perform a vaginal exam to see if there are signs of problems.
Hope this helps! If you have additional questions I can address, please let me know. Thanks!
Thanks Dr. Jill. I am not able to tell where the blood is coming from but I do not believe it is a skin irritation; there is too much blood and her skin looks fine. There is a small amount of discharge coming from her vulva and it is slightly reddish. There is so little though that I am not very concerned about that. I wouldn't necessarily say her stool is tarry either. It is just very dark. She seems completely fine otherwise.
Vulvar discharge is not uncommon in late pregnancy, so I wouldn't be concerned about a small amount either. One option is that she ruptured a varicose vessel inside the vaginal vestibule that bled temporarily causing the staining but has since stopped. Otherwise, the blood may have come from elsewhere, but sounds like there's no active source of bleeding that you're seeing. I'd suggest cleaning between her udder so you can monitor if this is an ongoing problem, but sounds like she's stable and doing well at the moment.
There are always exceptions to the rule, but in general with late term abortions in mares, there are few warning signs before the fetus is expelled. So assuming you haven't found a fetus in the area she is kept, she is probably still carrying a live foal. If she's in a large area or you're unsure, you can always have your veterinarian do a basic rectal palpation. That will give a quick answer to whether there's a foal still there and if they're moving and active. But assuming she remains otherwise stable, I think you would also be fine to wait and see, especially if the blood does not re-appear.
Hope this helps! If you still have any questions or concerns, please let me know and I will gladly address them. Thanks!