Natural worming for horses

Most horse owners are aware of the need to worm their horse to avoid symptoms such as weight loss, colic and poor condition and indeed, controlling the worm burden of your horses is an important aspect of caring for them. It must be noted, however, that healthy horses can carry a small load of worms without ill effects. It is even possible that in a healthy gut, a small infestation plays a supportive role in maintaining a balance. But there is no doubt that a heavy worm infestation in a horse can be very serious and may lead to all sorts of problems.
Nowadays, the usual way to control worms is with chemical dewormers. These offer the advantage of being extremely convenient: modern dewormers usually only need a single dose every 8 to 13 weeks, making them easy to administer to the horse, and, if used properly, will indeed kill all types of worms and prevent infestation. However, as is often the case, this convenience comes at a price. They are persistent, chemical drugs, designed to kill or disable worms, and some of them, particularly the so called "combination" wormers, can have serious side effects. The horse's body will have to process them (through the liver and kidneys), and one of them (moxidectin) is not recommended for foals or weak horses as an overdose can be very dangerous. Drug resistance is also a growing concern for many horse owners, and rightly so, as parasite resistance has been observed with ivermectin, moxidectin, benzimidazoles, tetrapyrimidines, and piperazine. Furthermore, the dung of horses treated with such wormers is not suitable for use as a fertiliser on organic farms as it contains chemical residues that would kill earth worms. For all these reasons, a growing number of horse owners are now looking for more natural ways of keeping their horses worm free. And the good news is, it is possible.

Most of the worms that affect horses have a somewhat similar life cycle: the horse swallows the worm larvae from the pasture, the larvae then spend a period of time developing within the horse before reaching adulthood within horse's digestive track. The worms then produce eggs that are passed in the dung onto the pasture. These eggs hatch into the infective larvae again. Breaking this life cycle through proper pasture management is an efficient and perfectly natural way of reducing worms infestation in horses. If the pastures are cleaned twice weekly, grazed in rotation by other animal such as cattle or sheep, and rested regularly for long periods, worm infestation will be greatly reduced and so proper pasture management should be part of every horse owners worming strategy. However, this alone may not be enough, and most likely some worming product will have to be used as well.
There are a few alternatives to chemical wormers for horses on the market. The best known is Verm-X, a herbal wormer available in powder, pellet and liquid formulations. We used Verm-X for a while at Macalla farm, until the faecal egg count of a horse who had been treated with it regularly at the recommended dosage came up extremely high, casting doubt on the product's efficiency. We contacted the manufacturer and they recommended treating the horse with a double dose, but we instead stopped using Werm-X and switched to  the Four Seasons' herbal and homeopathic wormer (available on line through  Bitless Bridle UK), sometimes used in combination with a home made worming preparation (see recipe below). The four seasons herbal and homeopathic wormer uses a combination of homeopathic ingredients which support the digestive organs, facilitating the natural expulsion of parasites via the animals own natural defence systems, and herbal ingredient whose astringent effects create a hostile environment for parasites. Faecal egg counts have consistently come back very low since, so this programme seems to be working well.  The Four Seasons' herbal wormer is also a lot easier to use (a single dose mixed with hard feed once a month at the full moon).
Another option we have started exploring recently is the use of Diatomaceous Earth, which is what Joe Camp (the author of "The soul of a horse, and now an expert in natural horse management) recommends. See the Soul of a horse blog article about it for more information. Diatomaceous Earth is available in Ireland from Willow farm organics

Is you want to make your own herbal wormer, this is a recipe that was given to us by Rachel Kelly, an equine herbalist practising in County Kildare (see her website at
Put 500ml of cold pressed organic olive oil (or good quality raw linseed oil) and 200g of raw peeled garlic cloves into a blender Blend it all up until it is like a paste, it only takes a few seconds. Leave this paste in a dark place for 3 days to macerate, shaking 1-2 times daily. Do not strain. (if using olive oil, you can make extra and use it as a salad dressing if you want). Use 40ml daily into horses feed, shake well before use. Must be stored out of sunlight in a dark container. The above recipe, she says, can be done with cider vinegar instead of olive oil, with the addition of wormwood. Using cider vinegar as a carrier adds minerals to the diet, aids digestion and brings the horse's body to an alkaline state, which is good to prevent arthritis and other conditions. Wormwood is a natural vermifuge which will cause the expulsion of worms from the body and along with garlic, which is a natural vermicide will destroys worms in the body. (Garlic is one of the main ingredients in the Verm-X formula mentioned earlier). You can even plant wormwood near where the horses drink and let them self medicate. It is also possible to add pumpkin seeds to the oil / garlic mixture. Pumpkins seeds are vermifuge and are very efficient against tape worm. They must be soaked for 12 hours before being put in the blender with the olive oil and garlic mix.
Rachel is a great advocate of feeding raw garlic to horses. However, garlic treatment, she says, works best over a continued period of time (which is probably why all the Verm-X preparation have to be taken for a few days in a row). Many horse owners feed powdered garlic to their horses, but, Rachel points out, while it is more convenient, some powders contain additional ingredients such as preservatives and non caking agents, so labels should be checked carefully. Furthermore, the medicinal value of garlic is largely in its sulphur compounds, (called allicin) which is only active when the garlic is crushed or cut and is inactivated by heat. This sulphur compounds is responsible for the odour and many of the medical effects of garlic, so raw garlic will generally be more efficient.
At Macalla farm, we occasionnally use the following recipe:
For 2 horse, put 250ml of cold pressed linseed oil, 200g of raw garlic cloves (no need to peel them), 50 g of dry wormwood (available online from and 50 g or organic pumpkins seeds into a blender. Blend into a paste and store out of sunlight in a dark container. Feed  50g daily for 5 days in a row, mixed with hard feed. It is much cheaper that Verm-X and just as effective!

Whatever method of worming you use, having manure samples tested regularly for the presence of parasite eggs should be part of every horse owner's worm control strategy. It is often cost effective to have regular faecal worm egg counts done for all your horses, because you can then avoid worming horses that do not carry any worm burden. Although worm egg counts don't show all the worms (encysted stages of redworm are not mature to lay eggs which are counted in the dung sample, and the test is not definitive for tapeworms, for which a blood test is available), but worm counts are still very useful, if only to get an idea of how your worming program is working. Westgate Laboratories ( offers a postal worm count service at a reasonable price (around 10 euros / horse, depending on the number of horses). And if you are worried that alternative worming strategies might not be efficient enough, a worm egg count may put your mind to rest.

Christophe Mouze with a lot of help from Rachel Kelly (
Article originally published in Horse and Pony Ireland