I manage my horses tying up issues through feed. His presented as back soreness over the kidneys and is now completely managed.
Firstly - NO GRAIN. That also means no grain by-products.
I switched him from a sweet feed onto beet pulp (Forage/bulk + carbohydrates), Copra (Coconut meal - high in coconut oils so very high in fat) and lots of grass hay, plus a mineral block in the paddock.
He did really well on this but didn't particularly like it, so at the moment I am trying out Prydes Easi-Sport - Completely grain free and low starch/low sugars, does have a small amount of molasses but appears to be handling it.
Other feeds suitable are micronised/steam extruded lupins, full fat soy, flax seed, rice bran, oils, and complete feeds especially formulated. We have Hi-Gain Zero, Happyhooves, Omega No Grain Gold, etc. Not sure what you have over there.
Make sure she is getting enough Vit E and Selenium - Won't fix the issue but are a great help.