NEWS
Pour it on, pack it in
Posted: Thursday, August 12, 2010 9:12 PM
ADHESIVES, PACKING, PAD, MESH PRODUCTS FOR THE HOOF
by Kenneth L. Marcella, D.V.M.
A revolution has been building over the last decade. It began slowly with the introduction of a few new products and a few innovative individuals that attempted to see where these items fit into what was currently being used, and it has grown from there.
Nontraditional shoeing methods and materials were first used for horses with problems.
Laminitic horses, unresponsive deep hoof cracks, rehabilitation cases, and horses with injured feet were the earliest recipients. These were the horses that were either not responding to traditionally available technology or were so severely damaged that even new and unproven methodology was worth an attempt.
As successes followed, trainers, veterinarians, and farriers began widening the application and use of these products. Horses in training, competition horses of varying disciplines and varying skill levels, world champions, and backyard pleasure horses have all benefitted.
Hoof packing materials, pour-in pad components, high-tech polymers and synthetics, combination pad and shoe designs, innovative boots, and countless other hoof care products are everywhere now and they have gone mainstream. It is worth taking a look at what has been learned over the last few years and where it has led the hoof care industry.
What to pack?
The question of what to pack in a horse’s foot has been around about as long as man has been putting shoes on horses. The need for packing arises because a shoe placed on the bottom of the horse’s foot supports only the area around the edge. An unshod horse uses its frog structure to provide support to the sole and coffin bone and to the rest of the bony column of the leg. Because of the specific demands of terrain or the particular needs dictated by certain sports or the conformational challenges (low heels; weak, brittle wall) faced by certain individuals, some horses need to wear shoes. When a shoe is affixed to a horse’s hoof wall, the entire hoof is raised and the frog loses much of its contact with the ground.
“A traditional horseshoe, though, is an incomplete shoe because it only addresses the hoof wall,” said Michael Savoldi, who served 28 years as resident farrier at California State Polytechnic University and now heads the Equine Research Center in Shandon, California.
Savoldi has researched and written extensively on the concept of uniform sole thickness, which is achieved when “the sole, at each point of connection to the hoof wall, is of equal thickness from heel to toe.”
If the sole is not trimmed to uniform thickness, then different amounts of pressure will be placed on different aspects of the foot and, as the horse loads and unloads its foot, the sole and the coffin bone (often called the pedal bone) will distort.
“Constant, long-term distortion of the sole will weaken and flatten the sole and cause remodeling of [the coffin bone],” Savoldi said.
A packing material, initially put under a pad, was intended to fill the space between sole and ground and to create equal pressure along the sole surface, thus helping to prevent distortion.
“If you look at a well-designed tennis shoe, for example, that is a very complete shoe because it has an arch support,” Savoldi said. “A regular horseshoe that is open in the center does not support the bone column, resulting in incomplete support.
“When the weight of the horse comes down on the leg column, the sole flexes and then recoils when the weight is lifted. With the extreme demands we place on these horses, the sole needs arch support to help in its recoil.”
More supportive shoes such as an egg bar or heart bar provide more support for the entire hoof capsule and some can engage the frog as the shoe is loaded, but they still do not completely address sole support. The restrictive nature of these shoes can lead to contracture of the heel and weakening of the heel wall, which is the area that needs to be as strong as possible.
Packing materials were originally simple and time-tested. Oakum is a natural fiber mixture that was used in early shipbuilding where it was pushed between planks in a ship’s hull and saturated with pine tar to make it tight and waterproof. It was a natural extension that these materials, oakum and pine tar, should be combined as early packing products for horses’ feet. The results were acceptable but not great.
“There are times when a horse needs a full pad between the shoe and the hoof,” farrier Richard Klimesh said. “The trouble is that pads often do more harm than good. Pads require a packing material to fill the space between the pad and the hoof to prevent soil, rocks, and bedding from getting under the pad and to minimize the growth of bacteria—but the packing is the problem.”
Adhesive advances
Earlier packing materials were hard to work with; messy; often resulted in soft, mushy hoof walls; and did little to prevent bacterial hoof infection or thrush.
In the late 1990s, the introduction of a line of products by Vettec Hoof Care Products began to change the way that hoof packing was used and the types of packing that were to be produced. Soft silicone and various polymer materials were soon becoming available from many manufacturers. Some types of packing consisted of two putty-like compounds that were mixed together, kneaded to initiate the chemical reaction, and then molded into the horse’s sole area. Others were silicone-based, and still others were synthetic mixtures that came as two separate compounds that were mixed as they were pumped onto the foot from a caulk gun-like dispenser. The soft-pour revolution had begun.
Companies such as DuPont experimented with Kevlar-associated hoof repair compounds. Advances in the field of adhesives, some coming from the National Aeronautics and Space Administration’s experiences with the problems of binding heat-reflecting tiles to the surface of the space shuttle, led to synthetic materials that could be used to build up a weak, brittle hoof wall in order to apply a shoe. These new materials were applied as thick liquids, cured in a matter of minutes, and then became physically part of the horse’s natural wall. They were strong; could be trimmed, sanded, and nailed; and had wear characteristics similar to the hoof itself.
Ian McKinlay, the renowned farrier who worked on champion and dual classic winner Big Brown, acknowledges that these adhesives were a huge step forward.
“Once someone made a glue that could replace a hoof wall, all sorts of possibilities opened up for farriers,” he said.
The development of many different products inevitably led to the search for the best packing for specific problems, goals, or conditions, and most veterinarians and farriers readily admit that has not quite been achieved yet.
“With all the different products available, most people tend to get comfortable with one or two products that they tend to stick with depending on the situation and the horse,” said Caleb Ruiz, a farrier servicing sport horses in Georgia.
However, Savoldi acknowledged the need to have a number of different approaches available to each farrier because each horse is unique.
“Some horses will need a softer packing material and more flexible pad while others will require firmer packing and a stiffer pad,” Savoldi said.
Many options are available through a number of companies, and new innovations are introduced weekly. Packing material has been available for a few years now that features copper sulfate impregnated into the pour-in.
Copper sulfate is a potent antifungal and bactericide and its presence in packing materials helps combat the development of thrush in feet that are completely sealed. This has allowed longer term use of hoof packing materials benefitting competition horses that need the support of packing material for extended periods of time. The relatively new Flip Flop shoe has been worn by the last two winners of the Hambletonian, Standardbred racing’s most prestigious event. This innovative shoe is part shoe, part pad, and, according to its supporters, it “looks funny but works great” especially on a hard track like the Meadowlands in New Jersey.
McKinlay said new pad innovations are helping more horses stay sound, adding “especially show horses and racing Standardbreds, whose feet get the worst beating of all.”
Proof of efficacy
What may be lacking in the midst of all these new pads and packing materials, however, is scientific research showing that they work.
Clinical impressions, farrier evaluations, and even racing and show ring victories aside, there is little hard science showing the effects of pads or packing materials on stride length, concussion, sole pressure, or impact-related vibration.
Research methodology is catching up, though, and sensors are being built that will help veterinarians accurately measure these effects. Data of this kind hopefully will help farriers and veterinarians decide which pads to use when and which packing materials to use where.
One study evaluated the effects of a specific type of plastic pad on impact-related vibration in trotting horses. The researchers concluded that “the studied pads did not dampen [lessen] hoof-impact vibrations at impact during the trot.” The researchers did acknowledge that they looked only at one specific type of pad at one gait using only eight horses. Many other variables exist that could have affected this study, and scientists themselves admit that they have only begun to scratch the surface.
Still, veterinarians, farriers, and those in the field caring for racing and other sport horses cannot help but be encouraged.
Cole Connell, a farrier working at training facilities in Ocala, feels that there has not been a horse that he has used pour-in pad material on that has not improved at least somewhat.
“I can get a decent heel to grow, especially on a horse coming back from the track with an underslung foot,” Connell said. “Within two to three shoeings, I’ll see a different foot and will get all the bruising out of the sole, and the horse will train better when he is more comfortable.”
Approach versus technique
Stephen O’Grady, D.V.M., a veterinarian and master farrier from Marshall, Virginia, feels that the technology and innovations can sometimes can cloud the actual issue for veterinarians and farriers alike.
“When people get hung up on technique,” he said, “they lose focus on the goal, which is to make this particular foot on this particular horse sound and healthy. When we use an approach instead of a technique, we’re far more likely to adjust it to an individual horse’s situation and needs.”
There is no doubt that new materials will continue to be developed and that they have and will continue to help veterinarians and farriers do their jobs. Andy Parks, M.A., Vet.M.B., a surgeon at the College of Veterinary Medicine at the University of Georgia and a member of the International Horseshoeing Hall of Fame, likes to remind hoof care professionals that the basics must still be attended to regardless of all the innovations and new products.
If veterinarians and farriers keep the basics in mind and use this approach, along with all the new products that technology will bring to the field, then the future for hoof care is truly limitless.
Kenneth L. Marcella, D.V.M., is a practicing veterinarian in Canton, Georgia.
