A horse that founders?

Brief：
A friend of mine has a mare that keeps foundering within a week or so of being put out to pasture. Once shes in the corral for a bit with her feed int.. 

A friend of mine has a mare that keeps foundering within a week or so of being put out to pasture. Once she's in the corral for a bit with her feed intake regulated, she gets better. But they hate keeping her away from the other horses. She gets lonely. Any advice?

There's still a lot we don't know about founder, but what we do know suggests strong links between laminitis and the high sugars and fats found in green grasses. Horses prone to founder are those who are introduced abruptly to pastures after having been on hay and grain for months before that. The abrupt switch over to grass can upset the horse's digestive system and start the process of swelling in the lamina which is a key indicator of founder. In order to avoid founder, the following steps should be taken:

If you have a horse that's been off grass for a period of a month or more, you need to take care to wean it back onto grass slowly. Start by hand grazing the horse for ten to fifteen minutes a day for a week. Then increase the time period to twenty or thirty minutes for the following week. During the third week, the horse can be grazed for forty-five minutes. Start grazing it for an hour in the fourth week. After that, you can increase the amount of time the horse spends on grass by an additional hour each week, working gradually up to a full day. This slow introduction allows the horse's body to get used to processing the added sugars and fats found in rich, green grass. It's not a simple or quick process, but it will help prevent founder.