when all else fails I have used Succeed with great success. It is expensive but worth every penny. my old TB mare inexplicably lost weight despite mine and my vets best efforts. she just wouldn’t eat and literally was skin and bones. I tried everything. she had a smorgasboard of feeds to choose from, teeth were done, hormones, antacids and steroids tried. finally a friend suggested Succeed which I had previously not heard of. I used the syringes as I knew she wouldn’t eat it but it comes in powder also. in two weeks she gained about 200 pounds and I cut her back to one syringe a day. her appetite returned and she had another 2 wonderful years when she died at age 27. She was my horse of a lifetime!