TYING UP

If your horse develops severe muscle cramping, call your veterinarian, then keep him still and comfortable until help arrives.

Bringing a horse back into condition after some time off must be done carefully: He needs to work up a sweat to gain fitness, but too much exertion increases the risk of several serious complications, including tying up.

Tying up, technically called exertional rhabdomyolysis, refers to severe cramping of the large muscles of the hindquarters, back and, sometimes, the shoulders during or after exercise. In some cases, damaged or dying muscle cells can release enough toxic debris into the bloodstream to stress the kidneys. Extreme cases may be fatal.

Repeated tying up occurs in horses with two specific disorders characterized by cellular dysfunctions in the muscles: polysaccharide storage myopathy (PSSM) and recurrent exertional rhabdomyolysis (RER). However, heat stress and/or electrolyte imbalances can cause virtually any horse who exerts himself to tie up under the right conditions. Here’s what to do.