Horsetail- Silica Rich, Vitamin B1 Destroyer

Horsetail – Silica Rich, Vitamin B1 Destroyer




Is Horsetail herb good for the horse’s coat and mane? Googled Horsetail but the sites was all confusing. One site said there was nothing wrong with Horsetail, they were using it to strengthen bones because it was silica rich. Another site said it was poisonous for horses but didn’t say why? A gypsy friend said “it looks like a horse tail so must be good for manes”. All this confusion and no proper answers. Please help sort my mind out on Horsetail.




Ellen C


Answer – Horsetail (also known as Shave Grass or Bottle brush) is the common name for the plant genus Equistaceae, a group of 25 species found throughout the northern temperate zones. In the UK, we have 7 species the most common being Equiseteum arvense. The name Equisteum comes from the Latin words Equus (a horse) and seta (a bristle) describing the bushy tail appearance of the plant.


It is an undisputed fact that all Horsetail species contain large amounts of silica. For this reason, Equisteum arvense was used in the past by herbalists, for bones, nails and hair. Horsetail has been frequently included in urinary formulas because of its duiretic properties. Externally, a decoction has been used to stop bleeding.


Research done in the last 20 years, has alerted herbalists and pharmacists to the toxins in Horsetail. Children in Canada using Horsetail stems as blow pipes and whistles were poisoned and had to be hospitalised. In Canada, manufacturers of herbal products containing Horsetail have to prove the thiaminase has been removed from Horsetail, before being included in a product.


Horses, cows, sheep and pigs won’t eat fresh Horsetail. Instinctively, they know this tough unpalatable plant is toxic. Hay containing 20 percent dried Horsetail given to horses resulted within a month, in toxic symptoms of severe neurological disorders such as paralysis, unsuccessful attempts to get up, and seizures. The condition of the horses were also affected by weight loss and general muscular weakness.


Although, Horsetail is rich in silica, it also contains the toxins thiaminase and nicotine. Thiaminase inactivates Thiamin (Vitamin B1) and causes Vitamin B1 deficiency, it also interferes with carbohydrate metabolism. Irreversible central nervous system damage may occur in severe thiamine deficiency. Thiaminase is also found in the bracken fern Pteridium aquilium known to be toxic to horses.


Avoid all products containing Equisteum arvense (Horsetail) unless the manufacturer can prove that the thiaminase has been removed. There are many silica rich herbs that can be used instead. The Equine Herbalist range of products from Epona Herbs are carefully researched and can guarantee that Horsetail – Equisteum Arvense is not included in any of their products.


Reference: Hamon, N.W., and Awang, D.V.C. “Horsetail”, Can Pharm Journal 125:399-401, 1992.


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