Salt and fluid balance

INRA (the European nutritional recommendation based on work at Wageningen University in the Netherlands) and NRC 2007 (the official US minimum standard) agree: 10 g of salt per 100 kg of horse per day only just covers requirements.

Swedish research spanning 25‑30 years reaches the same conclusion and splits the requirement into 2 g sodium and 8 g chloride per 100 kg, i.e. 10 g sodium and 40 g chloride for a 500 kg horse. The figures are agreed on in Europe, the USA and Sweden.

Kentucky Equine Research has no overall summary, but puts the macrominerals 1.3‑2.1 times higher than the NRC. Den Store Foderbog by vet Nanna Luthersson states 23 g sodium and 34 g chloride for a 500 kg horse in maintenance, equivalent to 55‑60 g salt, or 11‑12 g per 100 kg. Our recommendation, 10 g per 100 kg on top of Every Day Happy or Peak Performance (which provide approx. 3 g themselves) and 13 g in total with Supreme Minerals, is in line with the sources.

Long-term deficiency upsets the fluid balance. The horse finds it very difficult to regulate muscle work, energy and inflammation, and copes less well with sore hooves, muscles, joints and tendons.

A deficiency can be the direct cause of colic, because the horse drinks too little. It affects all muscle function, including gut peristalsis, which is smooth muscle. Salt is also a prerequisite for working energy and stamina, and for the horse to work correctly through its body and build or maintain a good topline.

In the past, horses got salt without anyone giving it a thought. Hay was salted, compound feeds contained more salt, and horses were fed much larger amounts of them, often 3‑4 kg of grain a day. Horses are hardly ever fed that way any more. Salt deficiency is probably a significant contributing factor in many horses' health problems, from colic to injuries in the musculoskeletal system, because when the muscles become overtired, other tissues such as tendons and ligaments are overloaded.

Salt requirements rise when the horse sweats during work, in hot weather and during pregnancy. During lactation the requirement is almost double that of maintenance and early pregnancy.

Also give extra after training and competitions, when lost salts and fluids need replacing. In hot weather, when your horse needs to be able to regulate sweating and temperature. And during transport, when a higher fluid intake keeps your horse from becoming dehydrated.

Horses that appear to overeat salt are most likely deficient and nutritionally imbalanced, and therefore exhausted or imbalanced in their adrenal function. The same is seen in other species. In studies where salt was removed for a period to measure the physiological effects, markedly larger amounts than maintenance were given afterwards to correct the deficit quickly.

The result of a lot of salt is that your horse gets thirstier, drinks more and urinates more, which can mean extra bedding. It is not dangerous when the kidneys, heart and circulation are working normally. If you want a real sense of how much your horse drinks, let it drink from a bucket or tub.

If you suspect your horse is overeating from the salt lick, give the correct amount of loose salt directly in the feed according to your horse's size and workload, and weigh the salt lick once a month. Usually there's no problem once you do the maths.

Salt can be mixed into the mash together with Every Day Happy, Peak Performance or Supreme Minerals. Soaked feed with vitamins, minerals, salt and electrolytes acts as a reservoir that travels through the gut, so the horse absorbs it at the pace it needs.

If you want to work out the requirement yourself, you can look it up in a feed programme such as SundHest.dk or in Den Store Foderbog. Then find a suitable measuring scoop so the amount is the same every day.

Electrolytes for horses: why salt is often the most important · Winter laminitis, circulation and salt · Horses need salt, published in Malgré Tout