If you've ever witnessed a horse actively tying-up--sweating, refusing to move, with spasming muscles--the level of discomfort far surpasses that of the usual aches and pains associated with hard work. | Photo: iStock

What we know (and still need to learn) about polysaccharide storage myopathy 

For the past several hundred years horse owners have struggled to care for charges afflicted with “Monday morning disease,” a crippling condition that affects horses after a day off from work.

“Although owners did recognize the terrible discomfort their horses were in, recall that horses were the primary means of transportation in those days,” says Stephanie Valberg, DVM, PhD, Dipl. ACVIM, ACVSMR. “Time off from tying-up was a major problem, effectively grinding the transportation system to a halt.”

Horse owners didn’t realize the condition’s severity and, so, carried on with their riding and driving as the symptoms cleared. Now, we know Monday morning disease is actually the muscle disorder exertional rhabdomyolysis (ER), more commonly referred to as tying-up, and it must be managed carefully.