Tying Up & Muscular Health

By: Dr. Lydia Gray

SmartPak strongly encourages you to consult your veterinarian regarding specific questions about your horse's health. This information is not intended to diagnose or treat any disease, and is purely educational.

Brief Description

“Tying up” or exertional rhabdomyolysis refers to muscle stiffness and pain after exercise. It can occur sporadically or chronically. Sporadic “tying up” is due to a temporary problem in muscle cells caused by fatigue, heat exhaustion, or electrolyte imbalance, and can occur in any breed. Chronic or recurrent “tying up” is an inherited problem with the way muscle cells use calcium, and is mainly seen in Thoroughbreds, Arabians, and Standardbreds. 

Supplements that May Lend Support

Horses with the sporadic version of “tying up” may have imbalances in their diet or inconsistencies in their training program. These issues may be corrected through the use of dietary supplements, a change of feed, or a more regular training schedule. When modifying the diet, particular attention should be paid to whether or not Vitamin E and selenium supplementation is necessary. The horse’s electrolyte requirements should also be considered.

Horses with the chronic version of “tying up” should also have their diet examined for the nutrients mentioned above. In addition, research has shown some benefit to supplementing with the minerals Chromium and Magnesium. There are also anecdotal reports of benefit from adding Dimethylglycine (DMG) to the diet.

Possible Diagnostic Tests

The signs of “tying up” can range from mild to severe and include the following, all associated with exercise:

  • Firm and painful muscles over the loin and croup
  • Excessive sweating
  • Quick, shallow breathing
  • Increased heart rate
  • Muscle tremors
  • Reluctance or refusal to move
  • Reddish-brown colored urine
  • Lying down/inability to rise
Exercise should be stopped immediately and a veterinarian called if any of the above signs occur. Diagnosis is based on history, physical examination, bloodwork, muscle biopsy, and possibly other tests such as a urinalysis or exercise challenge to discover the underlying problem. 

Prescription Medications Available

Medical treatment for a horse suffering from “tying up” includes keeping the horse hydrated by administering fluids, relieving the horse’s anxiety with tranquilizers, and making him more comfortable with pain relievers such as bute (phenylbutazone) or  Banamine® (flunixin meglumine). In addition, Robaxin (methocarbamol) and Dantrium (dantrolene) are muscle relaxants frequently prescribed for this condition.

Other Management Suggestions


The recommended diet for a horse with recurrent “tying up” has less starch and more fat, which can be accomplished a number of ways. First, make sure the horse receives 1.5 – 2.0% of his body weight in forage daily. Then, replace some or all of his grain/sweet feed with a commercial product specifically developed with fewer nonstructural carbohydrates. Depending on the product used, additional fat in the form of rice bran, oil, or powder may be necessary. In addition, electrolytes are recommended in the form of plain salt or commercial mixtures containing sodium, potassium, and chloride for horses in heavy training/competition or in hot, humid climates.


For some horses, the combination of stress and exercise leads to an episode of tying up. Use the following suggestions from the University of Minnesota College of Veterinary Medicine to avoid "trigger factors" in nervous-type horses:

  • Stall in a quiet area of the barn
  • Train first rather than last
  • Turn-out as much as possible
  • Avoid training regimes like holding back at a gallop or intervals that excite the horse
  • Tranquilize before exercise to prevent excitement
  • Treat lameness and another other medical issues promptly
  • Avoid stall rest or lay-up if possible, providing calm exercise if rested the day before
  • If necessary, give medications such as dantrolene orally one hour before exercise

About Dr. Lydia Gray

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