Azoturia
Also called „Monday morning disease" or „tying up". This disease traditionally affected draft horses that were rested on Sunday but still received full rations and were then expected to do a full day´s work on Monday. The condition is now seen more often in competition horses, especially those on a high plane of nutrition and an irregular workload
Cause
Traditionally azoturia was associated with overfeeding a resting horse with high energy feeds which resulted in large amounts of glycogen being stored in the muscles, especially the big muscle masses of the back and the hindquarters. A return to work and so a sudden demand for energy result to the build up of blood lactate following the rapid breakdown of the glycogen store accumulated during period of rest. When glycogen is broken down to release energy in the absence of oxygen, then lactic acid is formed. If eather large quantities of lactic acid are formed or if the acid is not removed quickly enough by the bloodstream, then the acid damages the muscle fibres. However, the susceptibility of those muscle fibres to damage can also depend on the levels of calcium that the horse has in its tissues, affecting the stability of the muscle cell wall.
Symptoms
The symptoms can vary from a slight decrease in athletic performance to the horse becoming anxious and recumbent. It sweats copiously. If only mildly affected, its gait might just be a little short behind. More seriously, it can come to a complete halt. The affected muscles, generally those of the hindquarters, rapidly become hot, very hard, swollen and very painful. A blood sample will detect high levels of the muscle specific enzymes creatine Kinase (CK) and aspartate transferase (AST). Also, the urine may be very dark in colour as the filtering system of the kidneys becomes clogged by breakdown products mainly myoglobin.
Treatment
If the horse is in acute pain, do not walk him, keep him warm and call a vet. Treatment consists of complete rest. The horse should not be moved, even by horse transport. The horse should be on a low carbohydrate diet. Anti-inflammatories drugs will help with the pain and intravenous electrolytes help the kidneys to eliminate the breakdown products.
Prevention
Strict attention to diet and workload are essential in order to prevent further attacks. Changing the ratio of nutrients to include a higher fibre content might also help.
