Changes in a pregnant mare?

My mom's broodmare, Delite, has suddenly gone through a lot of changes with her pregnancy. Mostly she's become insane, really really aggressive and territorial. But she's always been that way in the pasture, even if it's worse now, but I'm a little used to it.

There are two changes in her that are very very different than the ones my broodmare, Angel, goes through.

Delite has suddenly put on a ton of muscle, she looks like a stallion or my rig gelding. She has only been in foal since about July 27, and she looks like a completely different horse. I'm told that on top of the aggression could be a sign that she's going to throw a colt, is that true in your experience?

On top of that there is something weird up with her coat. Like any pregnant mare, she has an amazing coat, soft and fuzzy. But suddenly there are these single white wiry hairs that stick straight out all over her, and white spots that look different than the normal white spots horses get from pressure points. She has no roaning, sabino, or anything else that color wise could explain it. She didn't have a single white spot on her pre-pregnancy. I was just wondering what it might be. The white patches are a completely different texture than the rest of her coat and her blaze. She's 20 going on 4 if that helps. This will be her 4th foal, I think.

Anyway, wanted to check with the experts
Thanks!

We have a mare that's due in a few days and she has the same white hairs you decribed on her left flank. They appeared earlier in her pregnancy. I'm assuming that it's just their body going through changes.

Well I really couldn't tell you about the white hairs thing, as All my mares have a certain amount of white on their coats so never noticed anything different there, But about the aggressive mare throwing a colt.. I have had the opposite experience, my mare that was aggressive became passive during her pregnancy and was very loving. She has only given me colts so far...hoping for a filly this time round though.