Hoof Supplements: Feeding The Feet
Hoof supplements are big business. It only takes a cursory glance around any tack shop or feed store to realize that they're everywhere. They've got catchy names and labels, and lists of ingredients as long as your arm, all purported to help your horse grow tougher, shinier, more durable hooves.
Poor hoof quality is a complaint common to the owners of many types of sport horses, with Thoroughbreds likely being the worst offenders. And we all know the adage, "no hoof, no horse." So, it's natural that we look to nutrition to address our horse's pedal infirmities. But what do we really know about how nutrients translate into hoof horn?
Some of the feed ingredients promoted as hoof strengtheners do, in fact, have some dependable research behind them; others are based only on folklore or a manufacturer's assertions. Let's have a look at where your money is best spent.
Nourishing The Hooves
First, remember that any inadequate diet--whether it's deficient in protein, energy, vitamins, or minerals--will eventually make itself felt throughout the horse's body. He'll have a dull coat, poor muscle tone, no energy, and the growth of his hooves will be slower than normal, resulting in splitting, cracking, and difficulty holding a shoe. Take such an undernourished horse and provide him with a complete and balanced diet, and all of those conditions gradually will correct themselves. He'll grow better hoof horn, and produce it faster, because his body is being supplied with the raw materials he needs to do so.
Sometimes, though, horses grow poor-quality hooves despite receiving optimum nutrition. To some extent, we might have to blame genetics; while we have been busy selecting for qualities like speed, fancy movement, or jumping ability, we have neglected to breed specifically for good hoof horn. But it's also possible that we don't yet fully understand which nutrients contribute to quality hoof growth, and that our horses' diets might not be quite as correct as they appear.
The search for a recipe for tough, resilient hooves is nothing new; folk remedies, like feeding powdered gelatin, have been recommended by farriers and veterinarians for years. (Recent clinical trials have demonstrated pretty conclusively that gelatin doesn't work, by the way.) At various times, any number of nutrients have been implicated in hoof growth, but biotin, a B vitamin, has received the bulk of the attention over the past couple of decades.
As a nutrient, biotin is involved in glucose metabolism, the processes of cell growth and division, and the utilization of other B vitamins such as niacin. Because it contains sulfur, an element needed (in minute quantities) for the formation of the reinforcing bonds between strands of collagen, biotin plays a role in the health of all connective tissues (tendons, cartilage, and ligaments, to name three), as well as the haircoat and the hooves.
Reliable research supporting the use of biotin to encourage better hoof growth in horses, however, has been rather slow to surface; most of the reasoning behind supplementing equine diets with this vitamin comes from studies in other species, including poultry and pigs. In many animals, various types of hoof and/or foot lesions have been treated successfully by supplementing biotin, so it's a reasonable assumption that it might do the same in horses--but it's only in the last 10 years or so that research has begun to confirm this suspicion.
In one telling 1991 study, 42 Lipizzan stallions at the Spanish Riding School in Vienna, Austria, participated in a double-blind examination of biotin supplementation. Over the course of two years, 26 of the stallions received 20 mg of biotin daily in their feed, while another 16 stallions received a placebo. The conditions of the horses' hooves (which had been crumbly, thin, and had a tendency to crack at the weight-bearing border) was documented to have improved after they had been on the biotin for a period of nine months (with improvement being defined as a decreased incidence of hoof cracks, less crumbling of the horn, and greater measurable tensile strength). Further improvement in the hoof condition scores continued throughout the remainder of the study period. Meanwhile, the placebo group's hoof condition scores remained unchanged. This and a couple of other similar studies have at last demonstrated with some degree of certainty that there's something to biotin supplementation.
Mind you, there's still much we don't understand. For instance, we're still not entirely sure why biotin should need to be supplemented in horses at all. Many feeds, particularly growing forage plants (pasture), have what appears to be a more-than-adequate biotin content. On top of that, the helpful fiber-digesting bacteria in the equine cecum seem to manufacture enough B vitamins for all of a horse's daily needs as part of their normal metabolism. There is some question as to how much of those B vitamins are absorbed by the horse; they are created in the large intestine, while the primary site of absorption of vitamins is back in the small intestine. Equine digestive systems being one-way, the nutrients generated by the gut microflora might pass through the horse's system largely unused. No one is yet sure how much might be utilized.
Regardless, true biotin deficiencies have never been documented in horses except when they've been artificially induced (and that takes some doing). Feeding biotin at a level that has an impact on hoof growth is not really a matter of correcting a deficiency; it's considerably over and above that. In essence, it's taking a nutrient and feeding it at a level beyond normal requirements, at which it really becomes a therapeutic medication (the technical term is hyperalimentation). Fortunately, biotin, like all B vitamins, is water soluble, which means it is not stored in the horse's tissues. The body uses what it needs on a daily basis, and excretes any extra in the urine. That means there's very little chance of a horse developing a biotin toxicity, even when fed amounts many times greater than he needs for maintenance metabolism.
Why do some horses seem to need more than the maintenance amount of biotin? The jury's still out on that question. It might be because those horses don't absorb or utilize biotin as well as other horses, or they might simply have a higher requirement than horses with naturally good-quality hoof horn. But the fact remains that some horses with poor-quality hooves appear to respond positively to biotin supplementation. Not all do--and what separates the horses which respond from those which don't is another mystery.
It's worth noting, too, that there's still a considerable amount of controversy over what constitutes the "optimum" level of biotin for good hoof growth. Because of its high safety margin, many supplement manufacturers have taken the "if some is good, more is better" approach. The truth is that no one really knows the best dosage. The best guess we have at this point is that horses might be able to utilize about 15 to 20 mg of full-activity biotin per day.
Partners In Hoof Growth
It takes more than biotin to build a better hoof. In fact, Eleanor Kellon, VMD, notes in her book, Equine Supplements and Nutraceuticals: A Guide to Peak Health and Performance Through Nutrition, that, "Only an estimated 2% of horses with hoof problems have an uncomplicated biotin deficiency."
Several other dietary ingredients might influence the formation and strength of the insoluble protein called keratin, which makes up most of the hoof wall. Three sulfur-bearing amino acids--methionine, cystine, and cysteine--are largely responsible for the cross-linking that helps give the hoof material sturdiness and resiliency. They play a role in the maintenance of the skin, tendons, ligaments, and cartilage as well. Methionine, in particular, has attracted some attention because it's an essential amino acid (meaning the horse's body can't produce it on its own). Preliminary research, based mostly on pigs (animals with a monogastric digestive tract similar to horses), suggests that deficiencies of methionine in the diet might contribute to poor hoof quality, as well as tendon and ligament disorders and poor adaptation to exercise. There's very little hard data about the specific requirements of methionine in the equine diet at present, but it seems reasonable to supplement this amino acid if poor hoof quality is a problem--you'll find methionine listed on the label of many hoof supplements. All three of the sulfur-bearing amino acids can be found in good-quality protein sources, such as soybean meal.
Another nutrient that has been implicated in hoof quality is zinc. This trace mineral is involved in the health and integrity of hair, skin, and hooves (as well as immune function), and some nutritionists suspect that the majority of equine diets are deficient. Zinc is present in most horse feeds as well as in hay, but at levels too low to meet the recommended levels for good health; only wheat bran seems to have an adequate supply. For this reason, most com-mercially mixed feeds have supplemental levels of zinc added, but if you're feeding whole grains, or only forage, your horse won't benefit from this.
Adding zinc to the diet is a bit of a tricky business, because the absorption of this mineral is linked to the dietary levels of many other trace minerals, including copper and iron. Too much of one mineral will interfere with the absorption rate of another. Strict ratios of minerals need to be observed. (For one example, it's best to maintain a ratio of three parts zinc to every one part copper ingested.) Some sup-plement companies have improved ab-sorption rates of both zinc and copper by binding them to a protein molecule, a process called chelation. Look for ingredients such as "zinc methionine" on the label of a hoof supplement to ensure you're buying a chelated product.
The good news is that while we might not have established an optimum level of zinc for good hoof health, it has a very low risk of toxicity, so there's a considerable margin of safety in its use. Any time you supplement zinc in the diet, however, you should make sure that your horse also is receiving some supplemental copper (either in the hoof supplement itself, or in the feed).
Other nutrients that might play an indirect role in hoof quality include fatty acids, manganese, selenium, vitamin C, and other B vitamins. Any or all of these might make an appearance on the label of your hoof supplement; manufacturers like to hedge their bets, after all.
In a couple of cases, toxic levels of nutrients can contribute to weak hooves. For example, vitamin A ingested in excess causes a rough hair coat, skin disease, fragile bones, weakness, and brittle hoof horn. The only practical way to achieve vitamin A toxicity in your horse is to over-feed supplements that contain this vitamin, especially when you combine the supplements with alfalfa hay (which is rich in beta-carotene, a nutritional precursor to vitamin A). The cure is to balance the diet and stop supplying any-thing in excess of 30,000 IU per day.
Be careful with selenium, as well. This trace mineral is important as a partner with vitamin E in immune function, but it has a very low toxicity level. At levels as low as 3.3 mg/kg of feed, selenium can be poisonous. In addition to symptoms such as a loss of hair from the mane and tail, it can cause the hooves to separate at the coronary band and slough off. You really can have too much of a good thing.
One of the most important things to know about hoof supplementation is that it's far from an instant fix. You can't really repair a cracked or crumbly hoof; you can only try to encourage better growth from the coronary band down.
It's estimated that most light and draft horses grow new hoof wall at a rate of about seven to nine millimeters a month (or a quarter to a third of an inch). So, if there's improvement in the quality of the hoof, it will take from six to nine months, on average, to make its way down to the point where your farrier can trim it.
There's no denying the popularity of hoof supplements; in a survey of 501 readers of The Horse, more than 50% said they fed a supplement designed to improve hoof appearance or growth. Not all horses ingesting such supplements have problem feet, however; many owners feel they'll do some good by supplementing on a preventative level (though there's little data one way or the other on this approach).
Fed in the recommended amounts, the vast majority of hoof supplements will do no harm to your horse, but beware of feeding higher levels than suggested on the label, or doubling up with multiple supplements. Feeding too much of some nutrients can do more harm than good--excess sulfur, for example, blocks the production of collagen, the exact opposite of what you're hoping to achieve!
If you decide to feed a hoof supplement, be prepared to persevere for at least six months; it will take that long to begin to notice any improvement. (After a year if you don't see any difference, it might be that your horse is not going to respond to the product.) Remember to close the container tightly to keep the more perishable of the ingredients from degrading due to sunlight or moisture. If you're using a powdered formulation, mix or shake it up periodically to keep the contents from settling or separating.
This might go without saying, but don't expect the supplement to take the place of knowledgeable farriery. Regardless of the quality of his hoof horn, no horse is going to have functional feet if he's left for months without correct shaping and trimming of his hooves.
Creating Healthy Hooves
A study performed by Susan Kempson, BSc, PhD, Department of Preclinical Veterinary Sciences, Royal Dick School of Veterinary Studies, University of Edinburgh, Scotland, proved that horses which suffered from a variety of hoof problems improved by adding Farrierï¿½s Formula to their diet. The study was funded by the University of Edinburgh and Life Data Labs (which manufactures Farrierï¿½s Formula).
Eighteen horses of varying ages and breeds scattered throughout England and Scotland and suffering from either sand cracks and crumbling around nail holes or from frequent bruising, flat feet, collapsed heels, and often lameness, were fed six ounces per day for two years. Following routine farrier care about every six weeks, the hoof trimmings were sent to Kempson. Using electron microscopy, Kempson observed changes in the basic structure and shape of the cells and the cell-to-cell attachments of the hoof wall. In samples taken before Farrierï¿½s Formula was introduced, hoof trimmings did not have any organization within the white line, there were many holes, and the keratin squames (flakes) were loosely packed.
She reported that after six to eight weeks, the white line region began to show differentiation between the laminar and interlaminar horn. After one year, the horn structure was marked as good and formed a dense, cohesive structure with well developed horn tubules and intertubular horn.
Kempson said that some of the horses had been on other supplements, such as biotin, for up to two years and had shown no improvement until they were put on Farrierï¿½s Formula. Horses with sand cracks responded within six to 12 weeks, while horses suffering from bruising and lameness took seven to 12 months for response. However, all of the horses responded, and none suffered from a relapse within the time span of the study.
Kempson talked about one horse which had almost been put down due to hoof problems. The Thoroughbred eventer in the study had recurring lameness for 18 months and was extremely tenderfooted. Kempson looked at the hoof trimmings and found bruising and severe stress in the horn. After being on Farrierï¿½s Formula for six weeks, he showed improvement and was fitted with glue-on shoes. After nine months, the horse competed in his first event. He became a successful eventer.
In addition to improved horn structure, Kempson also found that horses on Farrierï¿½s Formula utilized their feed better, tended to put on weight, and had a healthier coat and skin.
Kempson noted that health of the hoof is related to nutrition and said the diet should be well balanced. She recommends putting horses on a maintenance dose of three ounces per day. "These days, because we are keeping horses in artificial conditions, I think horse owners should decide on what supplement they want and keep with that. You only need to feed one supplement," she said.
However, she cautions about creating an imbalance. "You have to know why you are feeding a supplement. And always stick with the manufacturerï¿½s dosage," she recommends.ï¿½Sarah E. Hogwood
About the Author
Karen Briggs is the author of six books, including the recently updated Understanding Equine Nutrition as well as Understanding The Pony, both published by Eclipse Press. She's written a few thousand articles on subjects ranging from guttural pouch infections to how to compost your manure. She is also a Canadian certified riding coach, an equine nutritionist, and works in media relations for the harness racing industry. She lives with her band of off-the-track Thoroughbreds on a farm near Guelph, Ontario, and dabbles in eventing.
POLL: University Equine Hospitals