Been reading up on my mare's allergies and have read that allergies to mold/pollen can cause heaves (apparently she does have allergies to those 2 things at least minimally, according to a allergy blood test...not sure how accurate that was, but that's another subject!)
Anyway, I've often wondered about the muscle definition she has under her belly...it goes the length of her belly and then diagonally up across her ribs. People have often told me it's from getting "stretched out" because before I got her, she was bred twice (she's 11 now and I got her from a rescue when she was 7 1/2...when they found her I believe she was a little over 6 years old (rehabbed for a year with a foster home before she came to me), and she had the second foal at her side when they found her, to give you some background).
So I'm wondering about whether that's even a possibility, or whether this is a heave line...she never coughs though, doesn't "roar" which cantering/galloping, and we Event, Fox Hunt, do Hunter Paces, Hunter/Jumper, we've done a lot of things together with no known issues with her breathing. So I'm kind of putting some feelers out here to see what others think!
This is the photo I have that shows the lines I'm referring to the most...