This is a disorder found most often in German Shepherds, so maybe you and your vet can do a little research on how they treat it in dogs to see if anything can be carried over into horses? In dogs, usually their only hope of survival is the addition of natural or artificial digestive enzymes to the diet. Thats where I'd start my research if I were you, perhaps consider contacting by phone or e-mail a vet or several who have treated dogs with this disorder to see if they can help. I know about a year ago I did some research for a customer and found one really good web forum and several decent sites regarding this, so I know with a google search (at least one geared towards dogs) there is info to be had on the net. Good luck with her, it is from what I understand a lifelong disorder but it can be managed. However I know in dogs its an expensive disorder to treat, so do your homework on the available treatments to find what works at the best price.