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Azoturia, also known as set-fast, tying-up or, most properly, equine rhabdomyolysis syndrome (ERS), is a disturbance of muscle function, best compared with muscle cramp, which can happen suddenly when a horse is being exercised.

Symptoms of azoturia in horses

  • The horse seems unwilling to go, may take short steps and feel unsteady or stiff on his back legs
  • The muscles of the hindquarters feel hot and hard
  • In some rare, severe cases the horse seizes up and cannot move
  • The horse can collapse and be unable to stand, so the condition can be confused with colic
  • The horse may appear uncomfortable and distressed

Basically, the muscles hurt and this alarms the horse. It will have a raised pulse and a slight increase in temperature. There may be frequent attempts to urinate. The muscle pain may prevent it standing in the normal stance to stale and, with severe muscle damage, the urine may be a red-brown to dark chocolate colour.

Treatment if you suspect azoturia

  • If you had bad cramp, you would not want to move, so in these circumstances you must stop and let the horse rest
  • Put rugs or coats over the horse’s back to keep it warm
  • Try to encourage the horse to drink, if possible. Fluids will help flush out the kidneys and reduce the problems associated with muscle breakdown. At the same time, it is sensible to watch that the horse is urinating normally. If the horse starts to produce Ribena-coloured urine, you need veterinary help.
  • Hay should be offered because feeding the stressed horse often makes it relax. The fact that you are providing a horse with a haynet to munch may help to reduce its anxiety, but avoid feeding concentrates, especially cereals. There are many specially designed feeds available for such cases, and it is worth obtaining advice from a nutritionist.
  • If at or near home, the horse should be put in a stable and offered water. A thick, dry bed should be provided in case the horse wants to lie down. If it does go down, let it do so and do not force it to stand up again.
  • If away from home, try to arrange transport home rather than riding back. A lorry is best, as it is less effort for a horse to stand in compared with a trailer, where it has to brace itself more, so using its already sore muscles.
  • In the worst and very rare cases, when the horse cannot move and may not be able to stand, contact your vet immediately, requesting emergency attention.

Once a horse has had an episode of azoturia, you should discuss future management with your vet. Blood tests may be necessary to monitor progress.

The tricky question is how to avoid it in the first place. Some horses, especially excitable young fillies, seem more prone to tying-up, but it is also more likely to happen in any horse that is over fed and under worked.

It is particularly common in a horse that is box-rested without properly cutting back the feed at the same time, or one that is overfed for the amount of work it is doing. A useful adage is always to increase the workload before increasing the feed.

This information formed part of a H&H feature about dealing with common equine emergencies, first published 19 January, 2006