Cross crate

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The cross lay or cross lay ( paralytic myoglobinuria ) is a disease that occurs in horses . It is an inflammation of the back muscles , which is associated with severe pain , comparable to very severe muscle soreness . Other names are shack or holiday sickness or SER ( sporadic exertional rhabdomyolysis ).


The symptoms usually appear quite suddenly at the beginning of greater physical stress on the animal, often after a previous period of rest (hence the English name Monday Morning Disease ). The horse begins to sweat profusely , does not want to move any more, trembles, often presses the back down and goes into a "sawhorse position", so puts the front legs forward and the hind legs back. In very severe cases, it kinks its hind legs and may also try to lie down. The heart rate is increased and a fever may occur. Overall, the muscles are hardened, especially on the back and croup . The breakdown of myoglobin results in a reddish-brown discoloration of the urine.


The reason for the occurrence of the disease is a metabolic disorder . If too much glycogen is stored in the muscles , not enough oxygen can be provided to dispose of the breakdown products such as lactate that arise when the muscles are stressed . As a result, the muscles over-acidify and fail, in the worst case even muscle cells can be destroyed. Myoglobin , responsible for storing oxygen in the muscles, passes into the bloodstream and is excreted through the kidneys .

Cross crating occurs when horses consume too many carbohydrates through their diet. These are converted into glucose and this in turn is stored as glycogen in the muscles, which draw their energy from it. If more glycogen is stored than the muscles consume through exercise, the metabolic disorder described occurs. Crossing occurs more frequently in horses after standing days if the feed ration is not reduced, or in horses that are moved irregularly but receive the same amount of feed throughout. However, regularly trained sport horses can also be affected.

Behavior in case of illness

Under no circumstances should the horse be moved any further, a veterinarian should be called in immediately. If the horse is on a ride, it should be picked up with a trailer if possible, as any further stress on the muscles leads to a worsening of the condition. It is also advisable to keep the croup and back muscles warm with blankets, even in summer.