In its mild form, this is a relatively common condition which affects the muscles of the horse’s hindquarters and back. Damage and inflammation of these muscles causes pain and stiffness. Azoturia used to be called ‘Monday Morning Disease’ because it commonly affected working horses following a rest day on Sunday. Azoturia are still often seen in horses on high energy diets after a rest from their normal exercise routine. In some individuals which appear to be particularly susceptible, notably young fillies, even a reduction in exercise for one day can result in the horse becoming tied up on resumption of normal exercise. Many cases are however seen when in regular work and are not seen following rest and other causes exist for this including electrolyte imbalances.

What are the symptoms?

Mild cases of azoturia just appear ‘stiff behind’ or 'stiff-backed' after exercise. Usually both sides of the body are affected equally so the horse does not actually appear lame. In more severe cases the horse may be very reluctant to move and show signs of pain such as sweating and scraping the ground. Some may be thought to have colic. Very severe cases may be unable to move and may even collapse.

What should I do?

If you suspect that your horse is tied up, stop exercise immediately and dismount. Sometimes a rider can detect very early signs by a change in action and this should not be ignored. If the horse can walk, return him to his stable. Do not keep him walking if he is reluctant to do so as this may worsen the muscle damage. If he is very stiff or unable to walk, get a horsebox or trailer to transport him to a stable. Moderate to severe cases should be seen by a veterinary surgeon as soon as possible. Initial treatment consists of anti-inflammatory medication and rest. Very mild cases sometimes respond quickly to tranquilisation. Severe cases may require intravenous fluids and intensive supportive treatment. Your veterinary surgeon will collect a blood sample to measure muscle enzymes to confirm the diagnosis and to determine the severity of the muscle damage. Follow-up blood samples will monitor response to treatment and confirm when it is safe to resume exercise.

Why do horses get azoturia?

This is a very complex condition and one which is not completely understood. In some cases it appears to be due to excess energy intake relative to the amount of exercise being received. In others electrolyte (salts) imbalances are suspected in the blood.

How can I prevent azoturia?

Ensure that your horse’s diet is providing him with the right amounts of energy, protein, vitamins and minerals for the job you are asking him to do. A pony being hacked out at weekends should not be fed the same diet as an eventer in full work! On ‘easy’ days, reduce the amount of feed you give your horse to reflect the reduction in exercise. If possible, ensure your horse gets some exercise every day, even if this is being turned out or lunging. Some horses who are prone to setfast can never have a complete day of rest.

If your horse has been tied up it is important to give the muscles time to recover. This can be monitored using blood tests. A gradual return to exercise after recovery is recommended so that there is no sudden increase to trigger another episode of the condition.

If your horse has a recurrent problem with setfast, your veterinary surgeon can collect samples of blood, urine and feed stuffs, for laboratory testing to determine if there are electrolyte, mineral or dietary imbalances which may contribute to the condition and require correction.