Azoturia – ‘Tying-up’

Azoturia is popularly known as ‘Tying-up’ but it is also known as ‘Set fast’, ‘Monday morning disease’ and ‘Exertional rhabdomyolysis’.

Azoturia is a recurrent syndrome in which excess urea and other nitrogen compounds are excreted in the urine following exercise. The urea comes mainly from the build up of toxic lactic acid and broken down muscle tissue, in the body, to their primary protein elements. These elements are circulated into the bloodstream to the liver where it is metabolised and broken down further into urea and other nitrogen waste products. This is then circulated back to the kidneys where it is filtered into the formation of urine.
Azoturia can develop rapidly and usually occurs when:

  • A horse in hard work is given a rest period without having his diet altered accordingly;
  • A horse is subjected to intense or prolonged exercise;
  • A horse is over-exercised following a period of rest.

Horses with azoturia will show signs of stiffness that can lead to the horse lying down in severe cases. Horses suffering from azoturia will also show signs of an increased respiratory rate, high temperature and possible sweating.
In severe cases the myoglobin released from the damaged muscles turns the horse’s urine dark red.
When ridden, the muscles over the horse’s loins and rump will stiffen resulting in cramps, the horse’s gait will shorten, it will stagger with it’s hind legs, go lame and may collapse if ridden work is continued.

If at any time, when at rest or while being ridden, you notice any signs of azoturia, you should call your vet immediately. If you are exercising your horse you should dismount and let your horse rest.
If the diagnosis is positive your vet will discuss with you the options for treatment and prevention. Treatment will include rehydration and pain relief. Rehydration with fluid therapy will correct any acid imbalances your horse has in it’s bloodstream. Other treatments may include the use of muscle relaxants and massaging of the affected muscles. The horse’s diet will need to be re-evaluated and he will require a period of rest.
Prevention is the most important factor when considering azoturia. Correct feeding and regular exercise will help to prevent azoturia. Any other changes in management and other stressors should be reduced and avoided if at all possible. In severe cases special feed supplements may be necessary, your vet will advise you accordingly.