Horses are herbivores. They do best mentally, physically, emotionally and spiritually when they get natural foliage to graze and pick on, with plenty of sunlight. Wild horses pick and choose what they need for both nutrition and medicine, and sometimes eat what are considered to be poisonous plants, for reasons that only they may know. Every year horses are poisoned from 'toxic' plants, most commonly when hungry horses are left with too little or poor quality food and they eat whatever else they can find. Unfortunately this can be fatal if a horse eats a highly toxic plant or too much of a mildly toxic plant.
What can we do as horse owners to ensure our horses do not get that which is harmful? Education is the best preventative for this. There is much to learn - a long list of plants can be found when researching poisonous plants for horses! Not to mention learning how to identify them all! However, some plants that are considered toxic may actually have benefit if eaten under the right circumstances and in the right amounts. Consulting with your holistic veterinarian and equine herbalist will provide many answers, as will texts on equine herbs, and an herb walk with an herb specialist can be fun and educational.
Comfrey is an herb that has gotten a lot of bad press in recent years for being toxic to humans and animals. To understand comfrey (Symphytum officinale), let's learn some history and chemical components of the herb. I use its leaves and roots for formulas, liniments, salves, and hoof sprays.
Comfrey has been noted throughout the years as a medicinal plant, a source of vitamin B12 and the cell-proliferant allantoin, and as a potential source of protein. Some strains of comfrey contain up to 35 percent protein, the same percentage as soya beans and 10 percent more than cheddar cheese!
Scientific attempts to extract the protein, in a form agreeable to human consumption, have been unsuccessful. However, the horse is not human and perhaps can and does absorb the nutrients found in this amazing plant. Comfrey is a valuable animal feed in some parts of the world - in Africa for example, where it is becoming increasingly important. Symphytum is also used as an organic compost and mulch - add it to your manure pile and let it grow around and in it for more efficient decomposition of solid waste (it contains alkaloids). Beware - once planted it will take over; it grows and flourishes, so pick it often and use it, in moderation.
In Medieval medicine, comfrey is mentioned repeatedly.
It was one of the main herbs used in treating fractures and because
of this, earned the name 'Knitbone'. The pounded root forms a mucilaginous
mass which, when bound around the fracture hardens and holds the
bone in place. It has also been taken internally for fractures,
weakened structural conditions and numerous other applications.
The constituents of comfrey are as follows: mucilage, allantoin (to 0.8 percent), tannic acid, resin, alkaloids, essential oil, choline gum, carotene, glycosides, sugars, beta-sitosterol and steroidal saponins (the saponins aid in the decomposition of the compost heap). Cell proliferation is due to the allantoin content.
THE CONTROVERSY - Both comfrey and the herb coltsfoot have become controversial because of their pyrrolizidine alkaloids (PA's), or chemicals that are toxic and/ or carcinogenic to the liver. Numerous herbalists and botanists have recommended not taking herbs that contain PA’s, wanting to err on the side of caution.
However, data published in the journal "Science" by renowned biochemist Bruce Ames, PhD of the University of California at Berkeley, indicates that a cup of comfrey leaf tea is less carcinogenic than an equivalent amount of beer.
The first reported presence of PA’s in comfrey was a study done by the Japanese in 1968. Australian researchers followed with a study in several plants of the Borage family. It showed rats fed up to 33 percent of comfrey leaf in their diet suffered liver cancer. One of the few follow-up investigations, using the whole plant, has shown the plant is not carcinogenic, but the exact opposite. As a matter of fact, Japanese doctors recommend a vinegar extract of the herb for cirrhosis of the liver.
To my knowledge, there have been no studies on the effects of comfrey on horses or cattle. I do know they like to eat it. A word of caution: no food or herb is good taken in excess. In dealing with comfrey, moderation is the best plan. I know many horse owners who keep a live, potted comfrey plant on the front wall of the horse's stall (outside where the horse can't reach it) and give the horse a leaf daily during the growing months. I have never seen nor heard of any adverse reactions. For all of my formulas that have comfrey in them, I caution horse owners at the onset of use to use only 2 pails, then discontinue. However, one particular horse who competes as a sport horse has chronic muscle cramping, and the only formula that has helped him contains some comfrey. His owner used the 2 buckets as suggested, and the problem had completely cleared up. Within 2 weeks of not using the formula, he again cramped severely. She insisted on putting him on the same formula again, and she has his liver checked (blood tested) every 2 months by a veterinarian. There has been no indication of problems. The veterinarian says her horse is healthier than he has ever seen him.
Now some good words about comfrey: It is one of the most famed healing plants in the world, an herb with a long history of uses throughout the ages. It has been used for tissue and bone problems, bruises, growth and repair of connective tissue, and cartilage. It is absorbed through the skin when used as a poultice, such as for varicose veins. It is used internally for gastric ulcers, inflammation of the stomach, back pain, regulation of hormones, infertility in males, and as an expectorant for the lungs and bronchials.
We use comfrey in many of our herb formulas for various conditions: for young horses in heavy training, for those who are nervous and off their food or perhaps have stomach problems, to help put weight on and encourage appetite, for horses with 'thumps', muscle cramping, fatigue and general weakness, for broken bones, encouraging healthy 'bone blasts' when the body is repairing broken or bruised bones, for OCD, and in our hoof spray, pre-trim softener, herbal salve, and cough syrup. All of our formulas contain compatible, acceptable amounts of the whole comfrey plant in them. It is best to be on the side of caution, and oversee the practical use of all plants, for yourself and your animals.
Loryhl, Herbalist, Herbs of the World, Inc.
CAUTION: Anything in excess could be harmful. In view of the controversy about this plant and the conflicting studies, I do not recommend continuous use or excessive consumption of comfrey. Consult your veterinarian and equine herbalist for guidance when using any herbs.
For more information:
Loryhl - Herbalist
Herbs of the World, Inc.
32 Conover Street
Freehold, NJ 07728
About the author:
Loryhl has been a practicing herbalist for 23 years and formulates for her company, Herbs of the World. She has advanced training in Herbalism from the Dominion Herbal College, and completed a 2-year intensive apprenticeship in human herbalism with Master Herbalist Doris Joiner in Canada. Loryhl incorporates herbal traditions from many parts of the world into her formulations in a synergistic balance using only human quality herbs. Her 5 children, horses, herbs, spiritual growth and alternative therapies are her passions in life.