Edema in "NOT" pregnant mare

[JUDYK89@aol.com]

I know most people are at the convention, but I hope there's someone out 
there who
 can answer this.
 
My new mare has been standing in her corral for 2 weeks (a little hand 
walking) because of all the rain here, and the ground is too slippery to do 
anything. Well, I 
put her saddle on her yesterday, and when I took it off, the girth left a 
huge "dent" in her belly (center fire girth). Now. she's had small "lumps" 
off and on since I got her, but now has this a big "V" starting from her 
chest, covering her rib area underneath. I asked my barn manager, and he's 
only seen it on pregnant mares (I've only had her since November so I guess 
anything's possible). She does have a filly on the ground approx. 1 1/2 years 
old now. My vet looked at her once when I first got her and said it's just 
because she's fat. Does anyone have this with a mare "NOT" pregnant (asking 
with her fingers crossed)?  Haven't been able to turn her out at all, maybe 
today the arenas will be drier.  Would this mean she has an underlying 
infection somewhere? Is this a side affect of post baby, standing around 
doing nothing?