If your pony hasn’t had laminitis to date then it is likely that not being able to consume enough forage is the most pressing issue as weight loss will soon ensue if this isn’t addressed. It is also much harder to put weight back on an older animal compared with trying to maintain it. A grass and alfalfa based chopped fibre feed such as Hi-Fi Senior would be a good base to start with alongside some soaked Alfa-Beet which is very low in sugar and starch so will help to bring the overall sugar intake down. Although Hi-Fi Senior does contain grass, the overall sugar content is comparable with a grass hay so presents no greater risk than using hay.
For horses and ponies with a history of laminitis, feeds such as Hi-Fi Molasses Free mixed with Alfalfa Pellets or high fibre cubes can be a lower sugar option than those based on grass. However, they won’t be as digestible and so a horse or pony may not do so well on them which may require some additional oil to be added to help maintain bodyweight safely.