by Peter Waller

Created on: February 20, 2007   Last Updated: June 25, 2009

There are several disorders of horse which can arise from through faulty feeding management. Some of these can result in severe lameness or death. This statement does not necessarily hold true for 100% of horses 100% of the time, however you may find that maybe one or more of your horses do suffer from time to time from the following conditions.

TYING UP

This condition is also called Monday Morning disease, Exertional Myopathy, or Myoglobinuria.

Tying-up typically happens when a horse is worked after a few weeks rest, without warming up, and after being fed a grain-rich diet during the rest period. It is not uncommon in pit ponies used in the Collinsville (Qld) mines in the 1930s/1940s period when untrained staff were used to look after the horses over the weekends.
There are two theories about why horses tie-up. the condition is certainly related to glycogen accumulation in the horse's muscles, but so far a reasonable explanation for why this happens is not clear.
The present evidence would suggest this-:
(i) Horses are very good at accumulating glycogen in their muscles - this means that if they are exposed to a 'carbohydrate loading' feed (high in cereal grains) they will overcompensate and store dangerous amounts of muscle glycogen.
(ii) Some horses are genetically predisposed to accumulating abnormal amounts of muscle polysaccharides. Of these, glycogen is only one example.
(iii) It is thought that muscle glycogen is oxidized as an energy source in the muscles of an inadequately warmed-up horse.
An earlier theory involved the build up of lactic acid, which may accumulate in the muscles for two reasons. 1. If a horse is not correctly warmed-up, inadequate blood flow through its muscles means that little oxygen is brought to the muscle and those muscles then forced to operate anaerobically. This is quite normal, but a lactic acid is formed under these conditions. Secondly, some muscle fibres (fast-twitch fibres) operate anaerobically anyway and the glycogen they use is converted to lactic acid, Muscle glycogen is normally recycled via the liver to glucose, but if large amounts are formed then this process may not work properly, It was thought that the lactic acid which accumulated in the muscles under these conditions simply acted as a relatively strong acid and damaged muscle tissue. This was then thought to cause the leakage of the muscle oxygen-carrying pigment (myoglobin) into the blood and eventually to its excretion in the urine. Evidence supporting this theory

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