EDITOR’S NOTE: The entry below was edited to answer readers’ questions regarding the use of softening and penetrating agents.
Hoof Nutrition Intelligence is a twice-a-month web segment that is designed to add to the education of footcare professionals when it comes to effectively feeding the hoof. The goal of this web-exclusive feature is to zero in on specific areas of hoof nutrition and avoid broad-based articles that simply look at the overall equine feeding situation.
Below you will find the latest question and answer installment that you can share with your footcare clients.
Q: What is the role of calcium in hoof health?
By Bryan Waldridge, DVM
A: Calcium is required in the diets of all horses for optimal health and well-being. This micromineral is needed in a relatively large amount, especially when compared to needed amounts of trace minerals.
Though calcium is aligned most often with musculoskeletal strength and soundness, as well as nerve conductivity, its importance in hoof health is unquestionable. However, a severe calcium deficiency in the daily diet is likely to have harmful effects on other body systems before a significant collapse in hoof health occurs.
The provision of a well-balanced diet will ensure that calcium levels are appropriate for the type of horse being fed. While a qualified equine nutritionist can determine if a horse is being offered a suitable diet for its age and use, most horses given a balanced diet will not have hoof problems due to poor nutrition. This is particularly true with young horses and those not engaged in demanding work.
In the hoof, calcium is present in minuscule amounts, approximately 300 to 350 mg/kg of hoof wall. One of calcium’s primary roles is assisting in the creation of sulfur cross-links between hoof proteins that allow for cohesion among cells. The stronger the cohesion, the more healthy and impenetrable is the hoof.
The amount of calcium found in the hoof is dependent on numerous factors. In a Virginia trial, mature Thoroughbred mares had 10 mares relegated to each of three diets:
1 An all-forage diet, in which the mares had access to pasture.
2 A drylot diet, in which the mares had free-choice access to 1-year-old barn-stored hay.
3 Forage and concentrate, in which pasture feeding was supplemented with vitamins and minerals to meet National Research Council recommendations for mature horses.
The 30 mares were allowed access to a mineralize salt block at all times and were fed their respective diets for at least 12 months year before the study began.
The average amount of calcium found in the hooves of these mares ranged from 906 parts per million (ppm) for mares on the drylot diet to 1,404 ppm of calcium for mares on the all-forage diet.
The researchers concluded that hoof wall characteristics, including calcium content, were influenced by the season of the year and nutritional management.
Bryan Waldridge is an equine veterinarian with Kentucky Equine Research in Versailles, Ky.
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Hoof Nutrition Intelligence is brought to you by W.F. Young Co. (Absorbine). 
Like many significant achievements, Absorbine® grew out of humble beginnings—and through the tenacity of someone willing to question the status quo. In this case, it was a young woman in late 19th-century Massachusetts: Mary Ida Young. Her husband, Wilbur Fenelon Young, was an enterprising piano deliveryman who relied on the couple’s team of horses to make deliveries throughout the Northeast. Inspired by Mary Ida and Wilbur’s vision, Absorbine® has continued to add innovative products throughout the years — products used every day by horse owners around the world. Which is why, since 1892, we’ve been The Horse World’s Most Trusted Name®.