Herbs: Where Do They Fit in Your Horse’s Diet?

The use of herbs as a source of compounds beneficial in promoting good health dates back many (many) thousands of years. In the age before ‘synthetic’ drugs, herbs were the only available source of potentially health-enhancing compounds and as such, they were used extensively. But where do herbs fit in a horse’s diet?

With modern day medicine now able to reliably reproduce the specific chemical components of plants that have the desired biological effect, herbs are not so prominent in the treatment or prevention of disease. Herbs are however still enormously popular both in human and equine diets. This newsletter is going to look, in a very broad sense, at how herbs are and perhaps should be used for equines.

‘Herbs are medicine’

The true and traditional role of herbs is to provide biologically active ‘medicines’ to treat or prevent disease states. I am the first to confess I know little about the use of herbs as medicine. A true understanding of how to use herbs effectively to treat or prevent certain diseases requires a full understanding of disease pathophysiology and the chemical actions of the herbs themselves. To understand all of this fully would take many years of committed study.

Herbs can certainly play a valuable role in the treatment or prevention of disease when used together with conventional or complementary medicine, but to use them effectively, they must be used correctly. Discuss the use of herbs or herbal preparations with your trained herbalist and ALWAYS include your veterinarian in these discussions. Quite a few herbs can have interactions with traditional medicines which if not fully explored can result in negative consequences. For example, ginger has been shown to increase bleeding time, so if it was used in conjunction with other anti-clotting drugs or if your vet was unaware your horse was being supplemented with ginger prior to undertaking surgery there may be complications with excessive bleeding.

Natural doesn’t necessarily mean safe

It is common for people to mistakenly believe that because herbs are natural, they are also completely safe. Because herbs contain drug-like components, many of them have the ability to become toxic if fed in too large an amount. Because a horse is such a large animal, the risk is, in reality, probably quite small, but you should always investigate potential toxicity for any herb you are considering to use. Garlic is a good example of a herb that, if fed in too large an amount can have negative consequences, with severe anaemia possible in this case.

Some herbs also accumulate high concentrations of certain minerals, with many plants being selenium accumulators and seaweed or kelp a good example of a group of plants that accumulate potentially toxic levels of iodine.

Additionally, even though some herbs can have positive effects, like nearly every modern medicine available, many also have the potential to cause negative side effects. Ginger, for example, has been shown to reduce post-exercise recovery time, but it is known to cause gastric ulcers in humans (presumably if it is taken regularly or in large doses) and is theorised to do the same in horses.

Herbs as nutritional supplements

Many herbal preparations are sold today as ‘complete nutritional supplements’ and yet are sold without any form of typical analysis to support the claim that they are providing a complete range of nutrients that the horse needs in its diet. Herbs are also used singularly to provide vitamins and minerals to a horse’s diet, but in very few cases are herbs actually able to provide enough of any nutrient to have an impact on your horse’s overall nutrient intake.

Herbs are just plants, and with the exception of selenium accumulating plants, seaweed which accumulates iodine, and perhaps rosehips as a source of vitamin C, herbs really aren’t capable of providing significant amounts of vitamins or minerals in a diet.

For example, garlic is commonly fed as a source of copper and selenium. While garlic does contain copper and selenium, horses are so large and the typical dose of garlic so small that adding garlic to a diet has no real impact on the diet. The table below shows the daily contribution of 250 grams of garlic (a massive dose and one that researchers at the University of Guelph, Canada observed to cause anaemia) to the diet of a 500 kg horse in moderate work (shown as percent of Recommended Daily Intake or RDI):

Nutrient % RDI supplied by 250 g/day dried garlic
Calcium 2.8
Phosphorous 3.25
Copper 1
Zinc 1.5
Selenium 2.75
Manganese 2
Iodine 0.0
Iron 1.5

Enter any herb we have in the FeedXL database to your diet and you will see that even in large doses they have little to no useful impact on the nutrient content of a diet.

That is not to say all herbal preparations are not worthwhile. Some well trained herbalists with a good understanding of nutrition have nutritional supplements that contain herbs together with more conventional sources of nutrients to give you supplements that do contain useful levels of vitamins and minerals together with complementary support from the herbs.

If you are buying herbal supplements that are being sold as nutritional supplements ALWAYS request a typical analysis. If one is not available, you should question how the supplier knows it is a nutritional supplement if they can’t even tell you what nutrients it contains. Don’t spend your hard-earned money on supplements that promise a lot without any sort of evidence to back it up.

Balanced diets, best results

As always, a balanced diet should underpin your horse’s entire health regime. While the use of herbs can certainly help support and promote good health or assist in the treatment of disease, if you are feeding herbs on top of diets that contain deficiencies of critical vitamins or minerals their effectiveness will be severely limited. Using FeedXL to first balance your horse’s diet, then working with your trained herbalist to devise a herbal strategy specifically for your horse will give you the best results.

Spice it up!

Herbs can certainly play a valuable role in maintaining or promoting the health of your horse. If you wish to use herbs as part of your horse’s routine health plan, you should keep the following in mind:

  • Use herbs only from trusted suppliers that can guarantee the consistent quality of the herbs.
  • Always discuss the use of herbs with your vet, particularly if your vet is also prescribing modern medicines for the treatment of a particular condition.
  • Understand the herbs you are using, particularly their potential toxicities so that you can use them to good effect without having them cause their own problems.
  • Don’t forget that very few herbs contain nutrients in high enough concentration to contribute substantially to any horse’s diet. If you are buying herbs as nutritional supplements always request a typical analysis for the product.
  • If you are using herbs like seaweed to provide a particular nutrient, always use FeedXL to calculate accurate dose rates to avoid overfeeding and creation of nutrient toxicity.


Dr. Nerida Richards is FeedXL’s resident equine nutrition specialist. With a degree in Rural Science, a doctorate degree in equine nutrition and nearly 20 years of full time, on the ground experience in feeding all types of horses Nerida is able to help FeedXL members solve any problem they may come up against with feeding their horses. To learn more about Nerida and to ‘meet’ the rest of the FeedXL team, check out our About Us page here.


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