PG . 37
IODINE AND SODIUM : Iodine supplements are generally required . Horses need 3-5mg of iodine each day . Iodized salt can be used to supply iodine and , depending of the amount of iodine in the salt , one-to-one-and-half tablespoons a day will meet the iodine requirements of most horses . The sodium content of feeds for horses is low and this amount of salt will also meet the sodium requirements of most horses . Two factors that greatly increase a horse ’ s water and salt ( ie sodium ) requirements are exercise and climate . During 3 hours of steady trotting in 21 ° C and 45 % humidity , a horse can lose 25kg in sweat and 250g (= 8 tablespoons ) of electrolytes . Even with a daily salt intake of 38g ( 1 heaped tablespoon ), it can take several days to compensate for sodium losses during exercise .
A horse in a paddock , even in the hottest weather , probably isn ’ t going to sweat enough to upset their sodium levels - with one exception : an older horse with Cushing ’ s disease . Cushing ’ s can cause excessive sweating . These horses can lose significant amounts of salt . And lactating mares - who during the 1st three months of lactation lose up to 6g of sodium (= 15g of salt ) per day in milk - require added salt .
Horses travelling in hot environmental conditions also need extra salt . Many don ’ t drink during transit . At the end of a 600km trip , they can be 3 % dehydrated and it can take them 6 hours to balance their fluid and body salts . Dehydration of 2-3 % can cause a 10 % reduction in exercise capacity and performance . Ensuring sodium ( ie salt ) intake is adequate before , during and after moderate to intense work can increase the time it takes for a horse to fatigue by nearly 23 %; that means a horse can work for 23 % longer before getting tired .
Horses on a hay or pasture diet , get plenty of potassium . But salt supplementation is a must . The relationship between sodium and potassium ( deficiency of which is very rare ) is complex . If the body is low in sodium it will conserve sodium
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MARCH / APRIL ISSUE 2021