Muscle Wasting, Azoturia, PSSM? Feeding???

^^ not sure for flax. But unground is heavier then ground.

Purena makes a few supplements you could look into as well. THey have something like grow n win, but you're probably better off just going w/ buckeye so you don't have to drive all over for different things.

I was thinking rice bran as well, just watch the calcium to phosphorus ratio.
I would just becareful, too much fat = very loose stool.

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.

Definitely call the reps. Buckeye or Progressive are excellent. Progressive makes Envision, hi fat, low sugar. Buckeye has a similar product. Also many senior feeds are easier to digest and easily absorbed, so that helps too. And be sure your hay is hi quality.

I would not rule out that she may have been on some strange drugs on the track (steroids or other things) that are now wearing off. Sad to say.

Correction. Don't call the reps, call directly to their nutritionists!!! Call their 800 numbers and they will get you in touch. Both buckeye and progressive have great nutrition experts that will work with you