Endurance And Electrolyte Loss

Horses are fantastic athletes. Their ability to adapt to nearly any task we put to them astounds many of us. Endurance horses are at the furthest end of the spectrum when it comes to athletic effort. Some even racing across 100km distances at canter speed! Equine metabolism plays a major role in providing the horse the fuel needed in these circumstances. The equine athletes' metabolic processes are a wonder in themselves, being able to provide what is needed in even these most difficult situations for prolonged periods of time is extraordinary.

Fluid and electrolyte losses can be high as a result of the exercise and with many of these longer distances being performed in hot, humid conditions; equine metabolism is stretched to the extreme. In extreme cases horses can show signs of synchronous diaphragmatic flutter, SDF. Signs of this are the contraction of one or both of the horses flanks, in time with the horses heartbeat. At this stage the horses metabolic rate is now unstable.

Low blood calcium levels are associated with SDF, highlighting the importance of the additional inclusion of electrolytes within the equine athletes diet. Sodium, chloride, calcium and potassium are vital. Calcium is essential for normal muscle contraction, triggering SDF when the level of this drops within the blood. A lack of ionised calcium causes nerves to twitch uncontrollably. The beating of the horses heart then causes the twitch to happen simultaneously alongside its beat as the abdominal muscles are supplied with blood.

Unfortunately the supplementation of calcium to the horse at this point has a detrimental effect. The strict regulatory methods of the horses metabolic system means that if excess calcium levels are fed, blood levels are high and the amount of calcium absorbed from the digestive system is much less. There is no "quick fix" with this problem occurs, prevention is better than cure. Many endurance horses are kept on a diet with increase calcium levels than that above required, keeping the system wanting more calcium. Additional ways of preventing SDF from occurring is to keep a healthy forage level in the total diet. When often this is overlooked in favour of additional electrolyte healthy foods, it has been seen that hay and haylage help to bind water as they pass through the digestive systems, providing an internal electrolyte store. Not reducing water levels prior to competitions (despite the additional weight carried from intake) will allow movement of electrolytes around the body to occur more freely.