Sodium (Na) is a very important mineral in the horse's diet. In fact, it could be argued that it is the most important...though as we've seen on other mineral pages, every mineral is essential to your horse's health.
There are a number of roles that Na plays in your horse's body:
Let's take a closer look at all of these functions, as they are all very important to your horse's health:
Nervous System Function
Na plays an important part in the nervous system by facilitating the movement of signals throughout the system.
Through action potentials, Na helps move the signals, which travel through excitable cells.
Works in Excitable Cells
When a signal moves through a neuron (a nervous system cell), it is moved by creating what is called an action potential. An action potential is nothing more than creating an extremely positive charge that moves from cell to cell.
When an action potential starts, Na (which is stored outside the axon -- a part of the cell) is pumped into the axon, while
potassium is pumped out of the axon. This creates a voltage change, which creates the impulse that allows the cells to send signals throughout your horse's body.
Transports Important Substances
Through various pumps and channels that are embedded in the membranes of every cell in your horse's body, Na transports substances that would not otherwise be able to get across the membrane.
These substances are generally water-soluble, as fat-soluble substances can get across the membranes because the membranes are made of lipids.
Some substances that are transported by Na include:
Maintains Acid-Base Balance as a Major Electrolyte
Na is one of the major electrolytes, and as such, plays a huge role in the acid-base balance of cells inside your horse's body. It also is very involved in the osmotic regulation of your horse's body fluids.
The more Na there is in an area, the more water will be drawn to that area. By regulating the content of Na in the kidneys, digestive system, and cellular fluid, your horse can regulate how much water is present in those areas.
Most feeds in the horse's diet contain very little Na. In fact, most of them contain less than 0.1%.
Therefore, it is very common to supplement Na in the diet, usually in the form of sodium chloride (NaCl), which is known as salt.
Many horse owners simply provide a "salt block" to their horses, either a white one that is all salt, or a brown one which also contains trace minerals.
It is actually not a very good idea to provide these blocks...
...the blocks were initially designed for cattle, which have very rough tongues. Because their tongues are so rough, cattle have no problem getting the required salt from the block by licking it. However, horses, who have much softer and smoother tongues, usually cannot get enough salt from the block before their tongue gets too sore (and even bloody in some cases) to lick any more. In fact, more than 4 out of 6 exercised horses do not get adequate intake of Na from a salt block alone.
Instead, it is ideal to offer salt free-choice in a loose form. This is best accomplished by hanging a bucket in the corner of the stall, or under a roof or other shelter in a pasture, and providing loose salt in it. This way the horse can consume as much salt as necessary.
Na deficiency is very rare in horses that are offered free-choice loose salt as described above. Na is the one nutrient that horses "know" when they are low on and will seek it out.
In fact, if a horse is chronically deprived of Na, he will try to get it through any means necessary, sometimes resorting to licking items in reach that were recently handled by a sweating person, as sweat contains a lot of sodium.
Signs of deficiency include decreased skin vitality, abnormal licking of objects (in search of sodium), decreased water intake, slow eating, and eventually loss of appetite.
For horses that are severely deficient in Na, they will not be able to chew correctly, may have trouble controlling their muscles, and often have an unsteady gait.
Toxicity is of very little worry in the horse, as it is excreted through the urine. However, if there is not adequate water available to the horse, it can become a problem. Without adequate water, the Na cannot be secreted properly.
Na is one of the most important macrominerals to your horse's health. Through its roles in the nervous system, transporting substances, and other areas, it plays a huge role in your horse's day-to-day life.
Thankfully, ensuring that your horse gets enough of this all-important mineral is as simple as providing loose salt free-choice in his stall or pasture.