This condition has long been a problem in draft horses and horses that are worked consistently through the week and then given a day or two of rest. Azoturia, also know as Tying Up Syndrome, Monday Morning Sickness, and Equine Rhabdomyolosis Syndrome, is a muscle and metabolic problem that results in painful cramping of the leg muscles, inability to walk and move, shortened stride and blood or dark coloration in the urine, excessive sweating and changes in gait and stride. If the azoturia is pronounced the muscles may appear very hard and stiff even to the touch and the horse may have problems in controlling the hindquarters, occasionally resulting in collapse. While not usually life threatening it can be serious once the kidneys become involved so early treatment and proper management of the horse is important.
Azoturia is problematic for horse owners and horses in that it tends to strike almost any horse, especially if they are on good feed and are well exercised and then stop or are just starting back into routine working. It is actually caused by the horse's body failing to properly use the nutrients in the food, which is typically fed as if the horse was being exercised. Foods that are high in proteins and fats may be more problematic as the body is not able to metabolize these foods when the horse is not being exercised routinely, causing a build up of myoglobins in the muscles which lead to the cramping and discharge of blood in the urine. Mares in heat and fillies are much more prone to azoturia as hormonal levels dramatically change in the body. Stallions and gelding may still show signs of azoturia but this will be food and exercise related more than hormonally triggered as in mares and fillies.
There are many different beliefs about the causes of Tying Up Syndrome. Most vets and horse breeders agree that hormonal issues, carbohydrate overloading with no exercise or sudden stops in exercise with no change in feeds, thiamine deficiencies that reduce the horse's ability to break down lactic acid in the muscles, as well as electrolyte imbalances in the working horse are somehow involved in the symptoms of the condition.
The good news for horses with azoturia is that it can be controlled and managed in almost all horses. The first episode of azoturia can be treated with anti-inflammatories (non-steroid is used in mild cases, steroids in severe), electrolytes through oral or IV means, mild, general exercise such as walking and careful management of feeds when horses are worked and then stopped or just starting into heavy work.
Horses should be provided routine exercise on a daily basis, and should, even on days when they are not being worked, be routinely exercised either through being turned out or by being walked to keep muscles active. Feed rations should reflect the workload, with lighter feeds that include more hay and less grain on days proceeding a day off or a series of days of light work.
Some work has been done with the addition of supplements to the diets of horses that appear to have chronic problems with Tying Up Syndrome include the addition of Vitamin E, selenium, sodium bicarbonate (baking soda) and even muscle relaxants at a very low level. Understanding the underlying cause of the azoturia with respect to each individual case will help in prevention and management.