She looks very sweet and I'm glad the chiro was about to come out and adjust her for you. She does look like she needs some extra groceries and light work (just for now) to build up some muscle. I would put her on a nice senior feed, I recommend Nutrena Life Science Senior, It's a very good feed and should help her out. I would also put her on a joint supplement and possibly put a mineral block in the pasture with her. That's always a good idea. With winter just around the corner I would try to put more weight on her and definitely keep her on a high quality hay, even with grazing in the pasture. More ideas to help you out are soaking beet pulp shreds and mixing it in her feed, it's pretty cheap and works wonders and/or mixing rice bran oil in her feed, really any oil with high Omega3s. I hope I helped! I've seen/used all of this stuff and I know it works.
I am Sparkly Meanie Doodie Head and I approve this message!