12/08/2024
Not just a grain of salt – why is it so important to add salt to your horse’s diet?
By now, I am sure many of you are aware that it is important to provide adequate salt to your horse or herd. But why is this specific nutrient so vital to their health? First, I want to cover the physiological role of salt and what it does in the body, and then we will discuss the best ways to add it to the diet!
When I was teaching Anatomy and Physiology to pre-vet students, we talked a lot about ions in the body including sodium, chloride, calcium, and potassium. These ions are present in bodily fluids and need to be available in appropriate amounts to maintain proper neuronal signaling, muscle contractions, transport, and digestion, among other important physiological processes. Additionally, these ions play a critical role in the fluid balance of the body specifically related to thirst, sweat, and urination. Considering salt is 40% sodium and 60% chloride, it provides two of these important ions that allow these functions to take place.
One of the most helpful ways I have found to explain the physiological role of salt is with the saying, “Water follows salt.” Let's simplify the physiological process that accompany this relationship:
💧 Increased salt consumption in the diet increases the thirst response and thus we drink more water and can become more hydrated.
💧 When we sweat, we not only lose water but other electrolytes, with sodium and chloride being the main culprits that contribute to the composition of sweat. This is because sodium is needed to facilitate the loss of water when we sweat and thus needs to be replenished in addition to water during exercise.
💧 Decreased salt intake encourages our bodies to retain the salt we already have. To do this, our kidneys decrease salt in the urine which subsequently decreases the amount of the water in the urine. This is because our body needs to tightly regulate the balance between ions (such as sodium) and the bodily fluids they reside in for many physiological processes to occur The result is a much more concentrated urine which is why you may hear yellow urine (which is more concentrated) is a sign of dehydration while a more clear urine suggests we are more hydrated.
So how is this connected to supplying salt in the diet? Unfortunately, salt will not be found in adequate amounts in most forages or horse feeds. While many commercially manufactured feeds provide adequate vitamins and minerals for horses when fed at the appropriate feeding rate, the exception here is sodium. This decision is intentional as sodium in a feed has been shown to reduce palatability. As a result, we as horse owners must add salt to the diet to ensure our horses meet their requirements.
This is an important feeding habit because when salt is consumed, the water will follow due to an increased thirst response. A hydrated state is critical in maintaining gut motility, which is the movement of feedstuff throughout the GI tract. Gut motility is very important to prevent digestive upset including conditions such as colic. Additionally, salt, water, and other electrolytes, are lost in the sweat of a hot or exercising animal. Providing salt in their diet encourages them to drink and replenish water and electrolytes lost during this process.
So how can we provide adequate salt to the horse? When I am in the field, I most frequently see salt blocks placed in the living areas of the horse. Unfortunately, these blocks were designed for other livestock and horses’ tongues are typically not rough enough to consume adequate amounts of salt from a block on a daily basis. While I still provide these blocks for my horses to allow voluntary intake, I also choose to top dress salt on their daily feed at a rate of 2 tablespoons (~30 grams) per 1,000-lb horse per day. This is often enough to meet sodium requirements of an average horse that is not in intense work.
What about the other forms of salt? I choose to feed my horses a loose iodized salt and you can often get a big bag of livestock salt at your local feed store! I choose iodized salt as iodine is an important nutrient that is not included on common forage analyses and can often be deficient in the diet (for humans as well which is why it was added to salt in the first place). The amount of iodine present in the salt is not enough to cause a toxicity but can help ensure your horse has adequate amounts of the nutrient.
Another common option I get asked about is Himalayan salt. While there may be some great claims on the label, this product is still 98% salt (with a few extra minerals) and often much more expensive. So if your horse is bougie or you want to create a certain ‘vibe’ in their stall, go for it! But it is by no means better or necessary to use Himalayan salts when compared to your average salt product. This is similar to the colored mineral blocks at many feed stores, which are essentially just pretty salt blocks. While they are not harmful, they can be misleading as they will not supply adequate minerals to the horse, such as zinc and copper, and therefore cannot replace certain feeds in the diet.
But while we may have favorites, feeding horses is just as much of an art as it is a science, and the main goal is to ensure the horse is consuming adequate amounts of sodium. As Dr. Rachel Mottet says, “The best kind of salt is the one your horse will eat!” If that means you have to provide Himalayan salt, go for it! But as always, consult with your equine nutritionist or veterinarian if you have any questions about your specific situation.
Happy Holidays!
Dr. DeBoer
