I've got a horse that is foundered (and he is over weight), do you have any way to help him at least lose the crest on his neck?

I agree with Sarah, only you should still give him good quality hay because he won't be grazing and needs to get nutrients from somewhere. Since he's foundered, his crest will stay broken over, but it will be minimized over time as long as he doesn't have access to grass or constant hay.
Thank u that's very good advice
Very low-quality hay and NO treats. Turn him out in a sand lot or arena, no fresh grass
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