It is possibly one of the most frustrating ailments that can affect an athletic horse. Tying up, also referred to as Equine Rhabdomyolysis (ERS), is a term generally used to describe a wide range of muscle disorders that affect a horse’s performance. A horse can experience severe, uncomfortable pain during this experience. It is comparable to severe muscular cramps in humans. Other names for this are set-fast, Monday morning disease, or Azoturia.

What are the signs of Tying-up?

During ERS, a horse experiences a plethora of physical symptoms. Some of these are very obvious while others are so mild that only diagnostics can determine if the horse has suffered from this ailment or not.

 Physical signs

  • Pain or discomfort experienced shortly after the onset or completion of an exercise
  • Cramping that may cause immobility in the horse
  • Stiffening up of the lower back, thigh, and gluteal muscles
  • Shortened and stiffened gait
  • Shallow breathing, excessive sweating, and increase heart rate
  • Reddish or brownish urine


  • Blood tests
  • Urinalysis
  • Muscle biopsy
  • Genetic testing


Although it is not fully understood why ERS happens in horses, affected horses have a few commonalities. These horses are typically fed a high-energy diet, and the diet is unaltered even when the horse has time-off from his regular exercise routine.

Some horses are more vulnerable to tying-up than others. It has also been observed that a horse’s hormonal cycle too has a role in contributing to this. Another major cause of ERS is electrolyte imbalance.


Tying-up is considered an emergency, more so if the horse is exhibiting symptoms such as immobility, profuse sweating, and dark urine. It is important to always consult a veterinarian when you suspect that your horse is experiencing episodes of ERS. Treatment can differ from case-to-case, but the general treatments are mentioned below.

  • Hydrating
  • Replenishing electrolytes
  • Relaxing the muscles
  • Monitoring blood and urine
  • Promoting blood flow and slight muscle movement
  • Blanket the horse in case it’s running a temperature


Management of tying-up in horses is typically dependent on the cause. But, in general, exercise and training regimes for horses must be carefully curated and the intensity should be increased gradually to avoid overexertion.

Tying-up in horses is also triggered by stressful events, such as separation from stablemates, environmental stress, trailering, etc. The living space of the horse should therefore be kept as comfortable as possible.

Needless to say, but a nutritionally balanced diet is essential to assure optimal health for the horse. This can also prevent hormonal and electrolyte imbalances, some of the cases of tying-up.


Tying-up or Equine Rhabdomyolysis (ERS) is a condition that causes uncomfortable and sometimes severe muscle cramping in horses. While the condition can occur due to various reasons, it can be prevented to an extent by proper management and training. Furthermore, a balanced diet is also essential to minimize the chances of your horse experiencing episodes of this ailment. In case your horse does suffer from tying-up, it is imperative to contact a veterinarian at the earliest. Treating this immediately can help the horse avoid this in the future.

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