Well, we have had more late term abortions/deaths than we have had live births. We think they were all related to Rhino, which is why my vet was JUST here giving the last of the mares their 9 month Pneumabort shots.
Mira aborted at 260 days in 2008 (she JUST passed 260 days last weekend - one reason I am a nervous wreck). No bag, no signs at all, and as a matter of fact it presented as colic. Called vet who was on the other side of the state, so told me to watch her and give her Banamine only if she got worse. Within a short time, I not only gave her the Banamine, but I called the vet back and said I was calling another vet because she needed help sooner rather than later. She was in such pain that she was rolling and thrashing while I was talking on phone to second vet. By that time we were pretty sure she was aborting but then her water broke and we were sure. Vet couldn't do anything so she sent us to hospital 2 hours away, where they worked on her for 3 hours to get the foal out. Breech presentation, and Mira surely would have died without intervention. The vets felt strongly that it was Rhino/herpes infection although the necropsy didn't show it. They had her in isolation the whole week she was there (you don't want to know the bill) and urged us to keep her away from our other pregnant mare. Of course, that was pretty much impossible, so the other mare (Sox) carried to term, bagged up normally, but foaled with NO SIGNS (I had checked her within 15 minutes) while my back was turned, and the foal did not get out of the sac. The placenta was delivered with the foal, all classic signs of Rhino, which does not always cause abortions but sometimes the mare carries to term.
Last year Sox lost another foal at 299 days gestation, just like the one in 2008. She bagged up normally but did not look that close to foaling. We already knew she had been exposed to Rhino, although of course we didn't know it back when she was first exposed. By the time we realized what it was, it was too late to vaccinate, so we knew she was carrying a "time bomb".
Both Mira and Sox recovered from their ordeals and were bred the following year(s). Mira presented us with Max in 2009 and Sox with Rusty in 2010. They are the two mares that just got their 9 month shots. Please keep fingers crossed for them.