Salt for Horses

This page provides a guide to the following topics:

  • Salt requirements. How much salt do horses need? Avoiding giving too little or too much salt. 
  • Independent comparison of different horse salts. This includes salt licks, salt blocks, loose salt, feed salt. Advantages and disadvantages of processed salt, mineral supplemented salt, unprocessed and natural salt (including Himalayan salt).
  • How to save money on salt. Which salts provide the best value for money and where can one get them.

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. 

Inadequate Salt

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:

  • With added salt, you control how much salt the horse gets, by adding the required amount to its feed. They argue that with free choice salt, some horses may consume too little and some too much.  
  • They also note that horses will sometimes chew on salt blocks, which can be extremely hard (some brands are almost rock hard), which risks damage to their teeth and jaw joints.
  • With added salt there is no wastage, whereas with free choice some of the salt can be lost (e.g. outside blocks eroded by rain, whereas blocks in a box can have pieces that break off and fall to the floor, which are lost when the box is cleaned out).

Those in favor of free choice salt defend their preference on the basis that:

  • Horses know how much salt they need. They will consume more when they need to (e.g. when losing salt through sweat, from warm weather or exercise) and less when they don't need as much. They can regulate their requirements better than an owner can guess at their requirements.
  • Free choice salt is more convenient. For example, if the horse is left out to pasture, with free choice salt you don't need to go to the horse each day to give it added salt. The horse will simply take what it needs.

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:

  • Horses will sometimes bite at a salt lick, which is not good for their teeth and jaw joints. However, I personally have only seen this with horses which were salt deprived and then given a salt block. At this point their body craves salt so much that instead of just licking what they need, they will try to chew it. In my experience, once a horse has eaten enough salt to make up for its shortfall, it stops trying to chew the salt block and will then lick it. If one is concerned about this, try giving the horse added salt for a period (e.g. a week) so that it can replenish the salt it is missing, and only then give it a salt block. If the horse still persists in chewing, one then needs to determine if it still has a salt deficiency (consider discussing with your veterinarian) or if it simply likes to chew on salt (I've never seen this personally, but other people indicate they have). In the latter case, added salt may be more appropriate for such a horse.
  • Horses can eat too much salt if given free choice salt. However, this is almost always when the horse is confined to a box much of the day and lacking mental stimulation, with the result that they lick on the salt excessively due to boredom. A horse which has lots of pasture time and contact with other horses will generally eat the amount of salt they require (horses are much more sensible than people in this regard). If you are concerned, the best way to check is the weight the salt block before giving it to the horse and note the date on the calendar. After a reasonable amount of the salt lick has been consumed, weigh it again and calculate the daily consumption. Then compare this daily consumption to the daily salt requirements explained above. If the horse is consuming greatly in excess of the expected required amount, discuss with your veterinarian if it would be appropriate to change the horse from free choice to added salt. Note that this checking mechanism only works if the free choice salt is in the horse's private box. If it is on a shared pasture or in a shared box, one cannot determine how much each horse has consumed individually.
  • The opposite problem of a horse eating too little salt can also occur. However, as horses naturally seek out and consume the salt they require, normally this should not be an issue. Again, if concerned, one can monitor the salt consumption using the method described above. Note that one needs to allow for any salt already present in the horse's feed, which will reduce the horse's requirement for salt accordingly. I've observed that the majority of horses prefer 'natural' salt to processed salt and will consume more of the former, so if you think your horse is not consuming enough salt then consider switching to 'natural' salt (see below).

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:

  • Natural Salt. This contains not only salt, but also various minerals and impurities which are to be found in sea water (ancient sea water, prior to modern pollution). Due to these additional elements, a block of salt is not pure white, but will contain other colors. Gray is a common color, although Himalayan salt is easily identified by the reddish color given by these added elements. Natural salt is normally sold in an uneven block.
  • Processed Salt - White. Processed salt consists of pure salt, with the other elements found in natural salt removed. As a result it is naturally pure white. It is shaped into uniform blocks prior to sale.
  • Processed Salt - Red. Iodine has been added to the salt and the block colored red to indicate this.
  • Processed Salt - Blue. Iodine and cobalt have been added to the salt. To indicate this, the salt block is colored blue.
  • Processed Salt - Brown. Various minerals have been added to the salt.

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. 

Various Forms

Salt is sold in various forms, including:

  • Irregular pieces. Natural salt is typically sold in irregular chunks, typically for free choice feeding.
  • Block. Processed salt is shaped into cubes, typically with a hold through the center. A string can be placed through the hole in order to tie the block to the stable wall or bars. Alternatively, the block can be placed in a special wall mounted salt holder, which has a plastic finger which goes through the hold to hold the block in place.
  • Lick. The term salt lick refers to a piece of salt; it can be used to mean either an irregular piece or a shaped block.
  • Loose. Granulated salt, which can be added to a horses's feed. If hand-mixing salt, check that the horse actually eats the salt as the salt may fall to the bottom of the feeder (due to it being heavier than the feed) and consequently may not be completely eaten.
  • Pre-added. Many commercial feeds have salt already added (typically up to 1% of the feed may be salt). Their is also trace amounts of salt naturally found in grass, hay and grain (although typically in amounts too low for a horse's needs).

One can also purchase electrolyte solutions which contain NaCL and other salts. See the section 'Caution' below for further discussion.

Cheaper Salt

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.

Caution

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.

  • This is a particular issue during endurance activities, when heavy sweating causes the loss of a lot of water and salt. Unless the salt is replenished, the horse may not drink adequately even when offered water at rest stops. It is then ridden after the rest stop, having drunk inadequate water, and then becomes severely dehydrated (a serious and potentially fatal condition). To avoid this, ensure that the horse's salt levels are replenished during competition and ensure that the horse drinks regularly and adequately.
  • Electrolyte solutions (which contain NaCl and other salts), which can be mixed with water, is often a good way to quickly replenish salt levels. If your horse is not used to these solutions, you may wish to offer it to the horse well in advance of endurance events so that it gets used to the taste.

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.