Tying up (azoturia)
Azoturia is relatively poorly understood and the exact cause is still unknown, however, what is clear is that it results in damage to muscle cells (myopathy). Azoturia is also known as "Monday morning disease", "Tying Up" and "Equine Rhabdomyolysis". Azoturia can develop rapidly and most often occurs when a horse in hard work is given a rest day without having its working diet reduced. It has always been thought that azoturia occurred due to increased lactic acid levels leading to muscle fatigue and cramps, new research has found that it may be due to a metabolic abnormality in muscle cells and so some horses have an underlying susceptibility to the condition which can be triggered by one or more exercise related factors. Mares coming into heat may also be prone to azoturia.
Signs
Horses with azoturia will become very stiff especially over the loins and quarters and the muscles will feel hard and be painful to palpate. The horse may have a high temperature and sweat. In severe cases the myogolobin released from the damaged muscles turns the urine dark red.
Diagnosis
The clinical signs are usually enough to make a diagnosis, however, a blood sample to look at the muscle enzyme levels can confirm the diagnosis.
Treatment
The horse should be dismounted and made to rest where it is and veterinary advice should be sought immediately.
In the initial period the objective is to control the animal’s pain using anti-inflammatory drugs such as phenylbutazone (‘bute’) or even sedatives if the animal is distressed. Some horses may require intravenous fluids if they are severely affected. The horse’s diet should be altered to reduce the amount of concentrate being fed and the animal placed on box rest for a few days. When the animal appears to have recovered a slow return to work should be implemented to prevent a subsequent attack.
Prevention
If a horse has a day off work then the concentrates being fed should be reduced and a long period of slow warming up carried out the next time the animal is ridden. Close attention should be made to your horse’s diet to make sure they are nit being over fed for the amount of work they are doing, see section on nutrition.