06/09/2026
Summer is here and extreme heat brings risks to be prepared for and prevent! One of these risks is tying up.
Exertional rhabdomyolysis or tying up is exercise related muscle cramping and damage. It typically occurs during dehydration, hot weather, electrolyte or diet imbalances, and/or heavy work. Some horses may only ever have one episode whereas others may have recurrent episodes that can be related to an underlying condition such as PSSM (polysaccharide storage myopathy).
Clinical signs include tucked up abdomen, muscle twitching in flank area, shortened/stiff stride, hard and painful muscles over hind end or back, or reluctance to walk. If severe enough, horses may also show signs of pain such as pawing, sweating, and increased respiratory rate. Some horses may even have dark urine.
Diagnosis is confirmed from physical exam, blood work looking at muscle enzymes, and possibly a urine test. Episodes of HYPP (hyperkalemic periodic paralysis) can present similar to tying up, but it is not the same. Blood work can help differentiate the two conditions.
Treatment varies depending on severity. Mild cases can improve with correcting dehydration and electrolyte imbalance by encouraging water consumption and allowing appropriate rest. Muscle relaxers such as methocarbamol or dantrolene can also be used. NSAIDs such as Bute or Banamine should be used sparingly as there is an increased risk of kidney injury from tying up episodes. Moderate to severe cases may need IV fluids for appropriate rehydration. Blood work will be monitored several times over a few weeks to ensure muscle enzymes and electrolytes are regulated before returning to work.
There are several things you can do to decrease risk of tying up. These include encouraging water consumption (can flavor water if needed), regular controlled exercise, gradual increase in workload to ensure proper fitness level, not having extended time off before heavy exercise is expected, light work during hot weather, keeping a high fat and low non-structural carbohydrate (NSC) diet as well as supplementing Vitamin E, Selenium, and electrolytes when appropriate.
As always, if you suspect your horse may be having a tying up episode or at increased risk to do so, consult with your veterinarian for a plan tailored to your horses’ specific needs.
