There has been a long-recognized association with the feeding of high-starch meals and the occurrence of tying up. Consumption of high-starch meals is commonly thought of as the cause of Monday morning disease, seen in work horses that were fed full rations on their day off and then suffered from tying up the following day when pulled out to work.

More recently, researchers have been able to link high-starch intakes to tying up in horses with certain genetic muscle disorders like polysaccharide storage myopathy (PSSM) and recurrent exertional rhabdomyolysis (RER). A horse with PSSM builds up too much sugar (glycogen) in the muscle tissue, and thus responds well to removal of as much starch as possible from the diet. RER horses can tolerate a moderate amount of starch, but a narrowly defined threshold often tips them over the edge.

There are a few nutrients that when deficient or imbalanced can lead to muscle problems such as selenium/vitamin E or calcium. Also when a horse becomes dehydrated and has lost a lot of electrolytes through sweating it can bring on a bout of tying up.

To avoid tying up, make sure the horse has a well-fortified diet with the proper balance of minerals and vitamins; back off or slow down if the horse becomes dehydrated; replace electrolytes when the horse is sweating intensely; and avoid high-starch meals if the horse is suspected of having either PSSM or RER.