NEWS
The biotin difference
Posted: Saturday, July 09, 1994
Biotin supplements, wisely used, can improve hoof quality over a period of timeNo foot, no horse. The old horseman's adage is as true in this day of Space Age shoeing options of lighweight titanium horseshoes and bonding agents that cure with ultraviolet light as it was in the times when all that farriers had to work with were iron bars.
When an animal is shod and reshod as often as a Thoroughbred racehorse, maintaining hoof integrity becomes essential to athletic success. The horse whose hoof walls are so thin, brittle, crumbly, or prone to cracking that he cannot hold his shoes on can miss training and racing days. The animal may also be working with subtle pain that can affect his attitude and how he runs.
Trainers often look to the feed tub to give their horses an edge in hoof quality, and most of the feed supplements purporting to affect hoof quality contain biotin. Does biotin really make a significant difference in hooves?
A recently completed three-year study by F. Hoffmann-La Roche, Ltd., a Swiss-based pharmaceutical company that wholesales biotin to feed and supplement manufacturers, provides evidence that biotin supplementation does improve hoof horn quality. The report also cautions that horsemen should not expect overnight miracles.
Dietary levels
Biotin is a water-soluble vitamin B-complex sometimes known as vitamin H. The microorganisms residing in the horse's gut synthesize enough biotin to meet the National Research Council's recommendation of two milligrams (mg.) of biotin daily for horses. The horse's body uses this biotin in various chemical reactions that create keratin, a protein used to build skin, hair, and hooves. The hoof structures that are considered keratin tissues include the sole, the frog, the white line junction with the inner-sensitive laminae, the hoof walls, and the periople membrane, which acts as a moisture barrier on the outer surface of the hoof wall.
Supplements first began including biotin for hoof growth when studies on poultry and swine indicated that those species grew better hooves, beaks, and other keratin tissues when extra biotin was added to their diets. That was enough for some researchers and manufacturers to say that adding up to 15 mg. of biotin daily to a horse's ration could improve hoof quality. Skeptics pointed out that although horses and pigs both have hooves, their digestive tracts function very differently.
A British study published in 1984 by Comben, et al., concluded that horses with poor hoof quality benefited from large doses of biotin, but advised that once hoof integrity was restored, the animals should return to a normal level of biotin. The researchers recommended therapeutic levels from 5-to-10 mg. of additional biotin daily for ponies and up to 30 mg. for draft horses. As a routine supplement, they recommended only 2-to-3 mg. daily.
The Lipizzan study
The most conclusive proof of the effects of feeding biotin to horses is the recently published Hoffman-La Roche study using the Lipizzan stallions at the famed Spanish Riding School in Vienna. Researchers fed 20 mg. of d-biotin daily to 26 of the white stallions, while 16 others in a control group received a placebo. Hoof horn grows at the rate of approximately one-fourth inch per month, so it takes almost a year for the hoof to grow from the coronet band to the ground. So the study's three-year length is significant because it means that the stallions replaced their entire hooves 2-to-3 times during the study period.
The Lipizzans were chosen as subjects because of problems they were experiencing with poor quality hoof walls and separation at the white line, which makes the foot more susceptible to infection. Researchers found no difference in the rate of hoof horn growth between the study group and the control group. The horses receiving biotin, however, had fewer microscopic cracks at the weight-bearing surface of the hoof, which translates into fewer chips and cracks. They also developed a tighter bond between the outer-insensitive laminae and the inner-sensitive laminae along the white line.
The 1984 British study found that some improvement in hoof quality was evident after 3-to-5 months, but that it took 9-to-12 months before severe cases improved. The Lipizzan study told the same story of patience before improvement occurred. It took nine months before the Lipizzans receiving biotin showed a statistically significant improvement over the control group. It took 19 months before the tensile strength of the hoof horn of supplemented horses improved over that of the controls, and 33 months before that difference became statistically significant.
The moral is that biotin, when it works, works very slowly.
Too much of a good thing
No symptoms of biotin deficiency are known in the horse, although other species exhibit them in the form of scaly skin, rough haircoats, or foot lesions. If horses, by and large, are not biotin deficient, what about the opposite side of that possibility-can a horse get too much biotin? Theoretically, since biotin is a water-soluble vitamin, the horse's body will simply excrete any biotin it ingests but does not need. However, one supplement manufacturer, who keeps the level of biotin in a daily dose of his product at five mg., cautions that overfeeding any nutrient can create an artificial need for it. Dr. Frank Gravlee, whose Farrier's Formula and Nutritone feed supplements were among the first to include biotin, points out that the horse can become "chemically addicted" to the higher level of the nutrient. When this supplement overdose is withdrawn, the animal may exhibit signs of deficiency. In the case of biotin, the horse's gut may also "forget" how to synthesize biotin on its own.
Gravlee and others argue that it is overall good nutrition, rather than biotin alone, that promotes healthy keratin tissues. The vitamins riboflavin and B6, the minerals copper and zinc, and the amino acids methionine, lysine, and cystine all play a role in the formation of healthy hair, skin, and hoof horn. They must all be in the horse's diet in the proper proportions for the animal to truly thrive.
As with all feed supplements, biotin must be fed within the context of the horse's overall nutritional program. The key is finding the correct balance that provides the horse with all the nutrients he needs to be his best, without overdosing him on vitamins and minerals that can throw his biochemical system out of balance with drastic consequences.
Bonnie Kreitler is a writer and publicist based in Fairfield, Connecticut. Rich Equine Nutritional Consulting in Monroe, Connecticut, works with farm managers throughout the country and in Europe to develop optimum feeding programs.
