Joe Ludford injects liquid silicone into a pad-and-shoe package.
Construction-grade (DAP) silicone has been used in farrier practices for over 30 years as a filler under pads with good success. At first, the set-up time could take as long as 24 hours and required some type of damming system like tape or putty to keep the silicone from leaking out the back side of the hoof and leaving a sticky mess. Now, with the new silicone materials, set-up time is 4 to 10 minutes and the development of putty-type materials allows a faster, much cleaner and more precise job.
The putty material is a durable commercial grade silicone that retains a consistent tone once it is set up. There are modern injectable silicones as well, which require a tip that mixes the hardener and the base silicone material precisely, so set-up times are consistent.
Both the injectable and putty forms are available in different levels of hardness. You can choose hard, soft and — in some cases — medium, depending on the application you are using them for.
Firm is the most supportive, but in some cases it can put too much pressure on the sole of the hoof. This is rare, but it can happen. Soft is often the better choice when your primary goal is to cushion a part of the hoof or for when you need filler.
Support Or Filler?
One of the first thing to decide when using silicone fillers is to decide whether you need structural support for the hoof structure or are just filling a void under the pad. Silicone fillers can function well for either purpose. But they almost always add columnar support.
When liquid silicone is injected into a shoe-and-pad package, the hoof is off the ground and non-weight-bearing. Ludford suggests using thumb pressure on the the pad to ensure that you don’t overfill the hoof cavity.
Support is needed when there is structural collapse of the hoof, such as laminitis, crushed heels, sheered heels, navicular-area soreness or heel pain. Silicone can be used in conjunction with several pad systems, but does not have its own adhesive character like some pour-in pad materials.
One of the advantages to using silicone instead of adhesive polyurethane products is that silicone allows you to better control the amount of sole pressure. This is because silicone has a slower set-up time than poly products. Polyurethane products set up while the hoof is not weight bearing. The slower set-up time allows silicone to set up while the hoof is weight bearing. This is a very important difference and you would be amazed at the amount of excess silicone material that vents out the heel area when the horse stands with its feet bearing a load.
How To Apply
This technique of applying silicone is very important and can guarantee that you will never overfill a cavity of the hoof, leading to too much sole pressure.
A farrier can decide just how much silicone putty to use and where to put it. If a sole is very sensitive, for example, the putty is applied behind the apex so there is no sole pressure ahead of it.
Silicone can be used in conjunction with flat pads, which work well for protection and provide some degree of support. Silicone can also be used with frog-support pads, which work even better for needed structural support of P3 and the bony column structure.
Weak laminae structure is the No. 1 reason why farriers have to add support. Silicone putty is the easiest and most cost-efficient method to combine with any pads. You control where the putty is in the hoof cavity by simply placing it only where you want it. In cases of laminitis, make sure that you never place any putty forward of the apex of the frog and always make sure that you stand the horse so he is weight bearing after you have tacked the shoe and pad in place.
In severe cases, I would recommend starting with just a flat or wedge pad and then progressing to a frog-support pad after the animal has improved to a less-acute situation. I have started using frog-support pads and silicone putty as an alternative to using heart bar shoes and have had great success. I believe this is because the frog-support pad, silicone combination is more forgiving then the rigid steel of the bar shoe.
Properly tapering the lap joint (scarfing) allows the edges of the materials to be properly blended during the welding process.
In the case of collapsed or crushed heels, an egg bar shoe can be used with either a flat or wedge pad and firm silicone to add support to the frog system. Usually after one setting, the heels are back where they should be and the frog becomes very strong and healthy. When using this kind of system, we are imitating what Mother Nature does in the wild by filling the hoof cavity with dirt. We are creating a complete structural-support system with a very strong and durable material.
The pad and silicone take the place of the ground surface. This eliminates the lack of ground contact that is created when a shoe is added. That lack of contact causes less frog support and some changes in the heels.
Silicone forms to the frog and sole, adding to the support system when used in conjunction with a pad. Ludford says the silicone, in effect, takes the place of dirt that would fill the hoof if it were living in a natural environment
Safe With Proper Use
Pads and silicones themselves cause no real health problems to the hoof cavity except for a little more retained moisture. Any disease, such as thrush or fungi or anaerobic bacteria, is either pre-existing or is contracted through mud seeping under the pads. Diseases can be controlled with a pre-treatment before adding the pad and silicone system or by simply applying medication under the pad at the heel area and allowing it to wash down through the hoof cavity.
Any copper-sulfate-based material should take care of most problems. In severe cases triple antibiotics, such as mastitis creams, work well.
The use of silicone and pads is a safe and easy, cost-effective tool that can be used by any farrier.