I recently bought a 14yr old 15.2hh Thoroughbred/Quarter horse and she is underweight a little bit. Some of the other people at the stables where she is kept told me to just continue feeding her as I have been but she hasn't gained anything. Her ribs continue to show and she continues to stay in one place when she is put in the arena with our other two horses. And even when she is by herself she stays in one place. (right by the entrance gate). The guy I bought her from kept her in his arena on rocks and very rough and uneven surfaces in the hot Hawaiian Summer sun with no shade and fed her very dry hay. She rarely had water to drink and now she drinks water like there is no tomorrow. But I am wondering if there is anything else I can do to help her gain the weight. I feed her alfalfa cubes with Purina senior feed and two sheets of hay.