Back home, already! We were in and out super quick, although I went to one about 22 min away instead of the closer one. The vet tenatively called it just a busted cyst, so you called it, Judy!
They shaved and cleaned it up, which revealed a far smaller hole than what it seemed like earlier. (What looked to me like a huge gash apparently was just the "innards" spilling out.) It was pretty anticlimactic to see how small the hole was, but definitely a relief! They said to keep it open-air, warm pack it several times a day to encourage purging of the rest of the gunk. There's still some stuff in there but didn't squeeze it all out because it wouldn't be "fair" to her. (Which I thought was a cute thing to say.) I'm supposed to have it lanced or something if it won't heal up in a few days. Apparently these things explode often. MP's a total bumpasaurus but none have ever burst! I just got charged for the exam. $118. They gave me some vet wrap and a gauze thing in case she bugs it. I'm sort of surprised I didn't get charged for the supplies.
Here it is, all cleaned up! Hard to believe this little hole pushed out so much entrail-y stuff! This is a much better image to go to bed with.
Thank you all for thinking of us!