I have a 30 year old Appaloosa named Shadow. When I took her in as a rescue she was severely underweight. So bad, that I had a friend tell me I would never get her back to a good weight and should put her down. She has gained over 100 pounds but just stopped gaining. I have her on Senior feed and worked up her rations but what else can I do to get her to gain some more weight? It seems like she got to a certain point in her weight gain and just stopped gaining.