Poseidon - you'd ideally have a better photo to work with... her front leg being that far under her is, I think, distorting her shoulder on you. Same with her hinds.
Other than that not bad. Her ribcage length actually isn't as "good" as you have, her LS is actually a little further back (it's right ahead of the point of croup) which makes her back just a little longer.
Ilium:body length 36%
Illium, femur and pelvis are all equal - strong hip?
Back:body length 46%
Rib:body length 46%
Rib:back length is 1:1 ratio (is that good)
Neck:body length 46% - acceptable
Her front legs are nice and straight, but she is a little sickle hocked in the rear. She was leaning backwards a bit in the pic I was using, so I can't say too much more about her rear legs. Her neck is proportional to her body and her back seems nice and strong with good loin strength (potentially?). My box was far from square, as her back is so short and her legs were a bit long to really be square.
(And I know she's still horribly skinny, but we'll get her better, I promise!)
Well, Dancer isn't standing well, for starters and that's making her look worse than she really is.
I've marked some corrections for you :
Even in this stance I got a shoulder slope of 54 degrees (which is steep, but not really critically so, and steeper than reality because of how she's standing) and an angle of 84 degrees (or so)... which is not that far off of the 90 degrees we seek, so while it is technically a closed angle, I'd like to see what it actually looks like with her front leg squarely under her body before I wrote it off. Your point of elbow was a little off too, making the angle look way worse than it really is.
The next big problem I see here, is actually where you have her LS, and Point of hip
I got 2.67cm for her hip length vs a 7.28cm body length. That's about 37% of her body length, which is a good length of hip. I got 2.3cm for her femur length, and 2.3cm for her pelvic length - so, even with her standing poorly behind, she's showing a pretty balanced hindquarter.
I got a back length of 3.2cm, which makes it about 44% of her body length, that's a nice length of back. Her ribcage length is 3.36cm... so it's more than equal to her back length - which is great, she has a short loin. Her LS placement is good too. She has a very nice deep loin girth.
What I wonder, looking at this photo is if she's pregnant? If she's not, I'd get her an aggressive deworming "program", as her stomach (if not very heavily pregnant) is showing some digestive distress. (I don't actually see a "skinny" horse looking at her... to me it looks like a wormy horse - a big barrel, decent fat covering, but still ribby)
We just recently wormed her (about two weeks ago) and will be hitting her again with Ivermectin Gold next week. She's always had a big belly, but she's not pregnant - she has a five month old filly that is about to be weaned. She lost a lot of weight just before the filly was born thanks to a neighbor that didn't feed her as promised and paid to do while we were on vacation. She's gradually been gaining it back in spite of nursing the monster filly. Dancer really got blasted on the forum a couple of weeks ago for being so skinny, but then again, we changed her feed a bit on the vets recommendation and she started gaining a little faster. That and the filly isn't nursing very much anymore.
She wouldn't stand still for the pictures yesterday. She was feeling too good. We had been lunging her for a short time and she wasn't ready to stop "playing."
Ah... just had a baby... that'll do it too! (Like people, it can take mares a little while to "trim down" again to their filly-ish figures!). She might be able to use about 50lbs or so, but then again, if she has worms, deworming her might be enough to pick that up. :)