[HairOfTheDog]

There is a "crease" or indentation that can appear running longways along the underside of the mare, that you can sortof begin to see in the grey mare in this picture:

I ~believe~ that is the increased blood supply running back to feed the babe, and the mare's udder.

There is a BAD thing that can happen where there is an actual rupture of her abdominal musculature, where the baby is 'falling to the bottom'. She'd be in pain.

You should not see this: Late Term Pregnancy Problems in the Mare - Ventral Ruptures

[HairOfTheDog]

Ping to my above... I think it's rare, but I saw one of these once on one of the emergency animal shows. It was more evident there than in the pic above.

[Rose of Sharn]

I am very concerned now. As the white horse, loks a bit like Sugar.