Biotin: Does it Work?

Here's what we know about the efficacy of this popular hoof supplement.

Conditions such as chronic laminitis, cracked hooves, or dry, brittle feet incapable of holding shoes are a common and time-consuming problem for owners, trainers, and veterinarians. Biotin is a popular nutritional supplement administered to horses to promote and maintain the growth of healthy hooves and coats. But does it work?

"In the equine world, biotin is revisited every few years," explains Ray Geor, BVSc, PhD, an equine nutritionist, the Paul Mellon Distinguished Professor of Agriculture, and director of research at the Middleburg Agricultural Research and Extension Center, Virginia Polytechnic Institute and State University. "It is rather frustrating because no new information is available to help owners decide whether or not they should be supplementing with biotin."

In this article The Horse presents an in-depth look at the current status of biotin supplementation in horses.

Biotin Basics

Biotin is a water-soluble B vitamin that plays an important role as an enzymatic cofactor in metabolism, meaning it is an inorganic complement to the enzyme reaction involved in metabolism. Horses, humans, and other mammals are incapable of synthesizing biotin. This vitamin must be obtained either through the diet or via the absorption of biotin that is synthesized by intestinal bacteria.

According to Carey Williams, PhD, equine extension specialist and assistant professor at the Equine Science Center at Rutgers, The State University of New Jersey, "Pasture is the number one source of biotin for horses. This vitamin is found in high concentrations in alfalfa, moderate concentrations in oat, barley, and soybean meal, and only in low levels in corn."

The amount of biotin required by horses remains unclear, particularly because the amount of biotin horses obtain from their feed varies between individual horses and groups of horses in particular geographic locations. Further, the amount of microbe-produced biotin in the hindgut (large intestine) that is absorbed and utilized by horses is also variable.

Biotin deficiencies are extremely rare in any species, and deficiency has not been reported in the horse.

Why Supplement with Biotin?

Readily available Expensive
Stable Might not work
Simple to administer orally with feed Because of the slow growth of hoof wall, it takes time to see any results
If effective, it can improve hoof quality, and, therefore, the overall health of the horse The supplement industry is essentially void of any form of government regulation. Therefore, poor–quality supplements exist.
Biotin was first discovered in the 1930s, when rats fed a diet based on raw egg whites developed severe dermatitis, hair loss, and neuromuscular dysfunction. It was later found that the protein in the egg white bound to biotin and prevented its absorption.

It was later found that biotin supplementation in humans might improve brittle nails and a variety of skin disorders. Enthusiastic extrapolations from these observations apparently led to the theory that if biotin can "treat" nail and skin conditions in humans, then it will also work on hoof and skin conditions in horses.

Evidence of Biotin's Effectiveness

Only a handful of studies have been performed in horses to determine the effect of biotin, and not one has been published in this millennium.

The most recent study was published in 1998 by a group of Scottish scientists from the Royal (Dick) School of Veterinary Studies at The University of Edinburgh. This experiment included four pairs of ponies that were apparently healthy and void of hoof capsular defects. The four ponies in the treatment group were fed 0.12 mg/kg of biotin--equivalent to approximately 60 mg of biotin per horse per day. After five months of biotin supplementation, the scientists observed a 15% increase in the treated ponies' hoof growth rates. The hoof capsule grew 35.34 mm in the treated ponies compared to only 30.69 mm in the control group.

Equally positive results were reported by South African researchers in 1992. This group found significant improvements in hoof hardness and growth rates in 24 riding horses fed 15 mg of biotin for 10 months.

"Not all studies on biotin report positive results," reports Williams. "After feeding 20 mg of biotin daily for nine months, no improvement in the rate of growth of the hoof was found in a Swiss study published in 1995."

When and How to Supplement

According to both Geor and Williams, horses that might derive some benefit from biotin supplementation include animals with dry, brittle hooves and cracked feet (e.g., quarter cracks), those that are shod frequently or that pull shoes often, horses with chronic, recurrent laminitis, and those with generally "bad" feet.

Current recommendations for biotin supplementation are based on the positive results obtained in the clinical studies in horses and extrapolations from results reported in other species, such as humans, pigs, and cows.

"I recommend that owners look for a supplement that will deliver 20 mg of biotin per day," advises Williams. "It is also important for owners to recognize that the results, if any, are not evident for eight to 12 months after initiating supplementation."

If owners are feeding more than one supplement, they should read the label of each supplement to determine the overall amount of biotin that the horse is receiving.

"Even though studies have shown that 60 mg of biotin is effective, a beneficial response has also been observed after administering only 15 to 20 mg per day," explains Williams. "More is not necessarily better."

Pros and Cons

Likely, the most important feature encouraging the widespread use of biotin is that it is extremely safe: no serious adverse events or toxicity have been reported in horses. Further, humans treated with up to 200 mg of biotin daily (equivalent to approximately 1,500 mg of biotin in a 1,100-pound horse) did not exhibit any signs of biotin toxicity. Biotin is readily available, it is stable, and it's simple to administer orally with the horse's feed. If effective, biotin supplementation can improve hoof quality and, therefore, it benefits the overall health of the horse.

On the other hand, biotin supplementation is expensive. Biotin supplements cost approximately 60 to 70 cents per horse per day, or about $200 per horse per year for biotin alone. While this price might not appear offensive to some, one must consider the total cost of all supplements and health products that the horse is receiving. The overall price tag can be daunting.

Aside from the fact that it might not work and can be, therefore, an unwise investment, biotin supplementation must be maintained for eight to 12 months before any positive effects might be observed, as Williams mentioned.

"The hoof grows from the coronary (coronet) band down to the ground--it takes time for the old hoof to be replaced by new, hopefully healthier, hoof wall," says Geor.

"One additional drawback to biotin supplementation, or any supplementation for that matter, is that the nutritional supplement industry is essentially void of any form of government regulation," explains Scott Weese, DVM, DVSc, Dipl. ACVIM, an associate professor in the University of Guelph's Ontario Veterinary College in Canada.

This lack of regulation permits the production of poor-quality supplements, including those that do not contain the amount of biotin that is listed on the label. A number of biotin supplements manufactured for human consumption have been evaluated by, a for-profit company dedicated to identifying quality health and nutritional products through laboratory testing. This company found several biotin supplements that did not contain the expected amount of biotin. While the company did not test any equine biotin products, there is no reason for owners to believe that biotin supplements produced for horses will be better-quality products than those produced for humans.

Biotin Buyers, Beware

In addition to the fact that nutritional supplements, including biotin, might not actually contain the type or amount of ingredient listed on the product label, other important concerns also exist.

"Nutritional supplements are not necessarily manufactured with the same degree of quality control as pharmaceutical drugs," says Weese.

As a result, nutritional supplements can be contaminated with other nutritional supplements during the manufacturing process, or the raw ingredients can be contaminated with harmful compounds such as heavy metals, herbicides, and pesticides.

While no known harmful interactions between biotin or any drugs have been found, and no toxicities have been reported, there is no reason to believe any supplement, including biotin, is universally safe. According to a recent article that Williams published, adverse events associated with herbal supplementation are an under-recognized and potentially serious problem in the equine industry.

"These days it is easy to oversupplement your horse." Says Williams. "Tack catalogs and supplement companies have hundreds of products available for every type of problem or ailment. Horse owners need to be careful when supplementing with more than one product. Some vitamins and minerals can be problematic--and potentially toxic--if administered doses exceed the recommended daily amount."

The Bottom Line on Biotin

"In my opinion, it may be unrealistic to expect that a small addition of biotin, or any supplement for that matter, will make a real difference in hoof quality," says Geor. "Alternatively, nondietary factors such as trimming, shoeing, and mechanical factors, perhaps in combination with biotin supplementation, may all contribute to improved hoof quality and rate of growth."

Despite its popularity, there is limited scientific "proof" that biotin actually impacts hoof growth, integrity, or any other quality pertaining to the hoof or skin. According to Geor, the type of research required to determine the true role of biotin in the horse is not likely to be performed.

"Evaluating the effect of a dietary supplement in horses is a challenging, time-consuming, and costly endeavor," states Geor. "Since a multitude of products are already available and widely used, product manufacturers are not likely to fund this type of study."

On a positive note, biotin is safe and there is some evidence that it can exert beneficial effects that have yet to be identified.

It is, therefore, the owner's or trainer's responsibility to decide whether there is enough evidence to confidently supplement with biotin.

About the Author

Stacey Oke, DVM, MSc

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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