Salt for Horses
This page provides a guide to the following topics:
Horse Salt Requirements
An average sized horse (400kg or 1000 pounds) requires a minimum of one ounce (about 30 grams) of salt per day. For larger horses, this amount should be increased proportionately and for smaller horses it should be decreased proportionately.
Note that this figure is a minimum. Horses lose a lot of salt in their sweat and a very heavily sweating horse can lose up to an ounce (30 grams) in about an hour; lightly sweating horses will lose salt at a much slower rate but if sweating for a long period (e.g. on a long, hot day), they can still lose a substantial amount of salt. The amount of salt which is lost through sweating needs to be added to the daily ration of one ounce (30 grams). For this reason, many people recommend 2-3 ounces (60-90 grams) of salt per day, to allow for salt loss due to sweating when being moderately worked or during moderately warm weather. Some authorities (e.g. National Research Council, Merck Veterinary Manual) express this as a percentage (0.5% to 1.0% of food, by weight) instead of an absolute amount, but the figures work out to about the same. Research indicates that above 3% is very unhealthy for horses, so one should aim to keep well under this amount.
Almost all foods (e.g. grass, hay, commercial feeds) contain some salt. However, in most areas the salt content in grass and hay is too low for the needs of a horse (the exception being grasses grown on very saline soil, such as in coastal areas, resulting in grasses with high salt levels). Consequently, a horse which is fed mainly on grass and hay should be provided additional salt, either as free choice or added to its feed.
Many commercial feeds have added salt (typically 0.5% to 1.0%), so a horse whose diet is largely based on commercial feeds may receive sufficient salt just from the feed and not require additional salt. For example, a horse which is receiving 5kg feed per day at 1% salt would receive 50 grams (almost 2 ounces) just from the feed.
Normal salt (NaCl) consists of Sodium and Chloride, both of which are essential for a number of critical bodily functions. These include heart contraction, skeletal muscle contraction, nerve function, water regulation, absorption of nutrients through intestine and into body cells, production of sweat and saliva. If the salt level in a horse drops extremely low, the interruption of these essential functions can be fatal (e.g. the heart will stop beating if there is too little salt). However, such sudden death from salt deficiency is rare, since horses normally receive sufficient salt in their feed (grass, hay, grain, etc.) to prevent such extreme results.
On the other hand, it is very common for horses which do not receive supplemental salt, to have reduced performance (e.g. speed, endurance) and to be more susceptible to various health issues. Salt is an essential part of nutrition and a salt deficiency, like any other nutritional deficiency, may or may not over time have health consequences. The risks will depend on the severity of the deficiency, the duration, the individual characteristics of the horse and how it is used. To avoid these problems, it is advisable to provide a salt supplement.
Added Salt versus Free Choice Salt
Salt can either be 'added' or 'free choice'. Added salts are added to the horse's feed (or sometimes, water) so that when the horse eats, he consumes the salt along with his food. In the case of free choice salt, a salt lick or salt block is placed where the horse has access to it (e.g. in the horse's box or on the horse's pasture) every day. Both approaches have their proponents, some of whom have strong opinions as to which is best.
These in favor of added salt defend this preference on the basis that:
Those in favor of free choice salt defend their preference on the basis that:
I personally prefer free choice salt. It is true that with salt left on the pasture, some will be lost to rain but usually this is not great and putting the salt under cover will minimize the loss. Likewise, with a salt block which is nearing the end, pieces can break off and be lost. This is more of an issue for salt which is hung from a string, with salt put into a spare feeding pot such losses are reduced (use a plastic feeder rather than metal, as the salt will rust a metal feeder much quicker). In any cases, there is some small loss of salt, but for me the convenience of not having to add salt to a horse's feed each day and not having to guess at how much salt it needs (based on how much was loss due to sweating from warm weather and exercise) makes up for this small loss. Potential issues with free choice:
Natural versus Processed Salt
Most salt for horses is mined, from deposits resulting from the evaporation of ancient seas which were then buried underground. As such, it contains a number of minerals and impurities which were left behind. Salt can also be produced manually through the use of sea water drying beds, but due to the higher cost such salts are normally used for the human gourmet market rather than animal consumption.
Once the salt is mined, it can be purchased either as is (with the various minerals and impurities) or it can be processed. Processing removes the various minerals and impurities, resulting in pure salt (sodium chloride or NaCl), which is completely white in color. The processed salt can be sold as a block of pure salt, or one can buy variations which have had specific minerals added (in which case the blocks are artificially colored to show which minerals have been added). This results in the following possibilities:
In my experience, horses prefer natural salt to processed salt and will consume more of the natural salt. In fact, some horses will refuse to eat processed salt unless they are desperately low in salt. Horses are evidently attracted to the minerals found in unprocessed salt, a number of which have been shown to be beneficial. At the levels found in natural salt, none of the minerals and impurities have any health risks.
Processed salt has the advantage that it is much cheaper than natural salt. It can be argued that it provides even better value than the price per kilogram (or price per pound), as processed salt is pure, without wasteful impurities. Consequently, processed salt is the choice of the price oriented consumer. It is also more convenient in that it is shaped into uniform blocks which are easily stored and one can buy corresponding salt holders which are plastic containers designed to hold the blocks (this does not work with natural salt, which is typically sold in irregularly shaped pieces).
I use natural salt for our horses and recommend it to clients at our horse stables for their horses, particularly for horses which are excessively reluctant to consume processed salt. Personally I use Himalayan salt, which I consider to be among the best for horses. Although it is much more expensive than processed salt on a per kilogram basis, a piece of salt lasts so long that on a per-month basis it does not add greatly to the cost of keeping a horse. With salt such an essential element of a horse's nutrition, along with the additional beneficial minerals found in natural salt, I consider it a good investments in the horse's health.
Salt is sold in various forms, including:
One can also purchase electrolyte solutions which contain NaCL and other salts. See the section 'Caution' below for further discussion.
If on a tight budget, processed salt is the most economical choice. It is also worth comparing prices on the internet with the local retail shop to determine which is the cheapest supplier (for internet shopping, remember to factor in shipping costs).
With free choice salt, it is important to avoid wastage. For salt which is provided on the pasture, placing the salt under cover (but still accessible by the horses) will prevent loss from rain erosion. For salt which is provided in a box, placing the salt inside a plastic feeding trough will help prevent pieces which break off from being lost in the straw and manure on the box floor.
If a horse has been salt starved and is then given free access to salt, it may eat too much at first and make itself ill. It is best to control the amount of salt it gets until its craving for salt stablises, for example by giving it access to a salt block for only short periods at first (and under supervision) or by starting it off with added salt for some days before giving it free access to salt.
For most horses, free choice salt works well. However, with some horses there may be problems (too little salt, too much salt, salt chewing). Consequently, when giving a horse free access to salt when it is not used to this, one should monitor at first to make sure that it does not have any of these issues. See above discussion on free versus added salt for more details.
When buying salt, always check that it is intended for horse consumption. Processed salt intended for other types of animals may have supplemented mineral levels which are suitable for those animals, but which may be unsuitable for horses.
Horses with inadequate salt may not drink enough, even when dehydrated. The reason for this is that blood salt levels is a major factor in a horse's desire to drink, so if salt is low it may not want to drink. The expression "You can lead a horse to water but can't make it drink" is very true.
Do not offer salt to a moderately dehydrated horse or severely dehydrated horse. In such cases, the short term effect of feeding salt is that the salt will draw water into the digestive system, further dehydrating the horse. It is important to first fix the dehydration issue and then one can replenish missing salt.