March 25, 2021 
When it comes to hoof cracks, some are superficial and have no effect on the hoof whatsoever, while others can penetrate all the way through the wall and into the sensitive tissues below, and possibly up into the coronary band, as well. Some cracks will resolve on their own, others need intervention, and some will be permanent, no matter what you do.
The first step in dealing with a crack is figuring out what kind of crack you are looking at. Once you know that, you must determine what is causing the crack so that you can address the problem. In this excerpt from The Essential Hoof Book, writer Susan Kauffmann and Christina Cline tell us what is usually behind one of the most common types of hoof crack—the toe crack.
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While toe cracks can appear for many reasons, they are most often due to a combination of mechanical stresses in the toe region paired with compromised laminae that cause a lack of good connection between the wall and the coffin bone.
The reason these two factors so often work in tandem is that poorly connected walls are more vulnerable to mechanical stresses, but mechanical stresses can also weaken the laminar connection. So, whichever one happens first, it opens the door for the other one to follow.
Mechanical stresses on the toe may include anything that pulls, pushes, twists, levers, or loads the wall horn. These stresses are not normally a problem for a healthy foot, but they can easily start or worsen a toe crack when the toe wall is already set up to fail for any of the following reasons:
• Dorsopalmar/plantar imbalance: This common hoof capsule distortion typically manifests as the front part of the foot having more mass than the back, which means you have a long toe and a point of breakover that is too far forward. With every step, the toe on such a foot experiences tremendous levering forces as the rest of the foot tries to roll over the toe to get off the ground. The levering forces weaken the laminar connection and put tensile stress on the bonds holding the tubules together—a double whammy of crack-causing potential.
• Toe flares: Dorsopalmar/plantar imbalance and problems like laminitis can lead to toe flares, which are a sign that the toe wall is not well connected and is being stretched and bent. If toe flares go unchecked, cracking is likely to follow.
• Medial-lateral imbalance: This side-to-side imbalance exerts shearing forces on the toe when the hoof lands unevenly, with one side of the hoof being pushed up upon impact while the other is still descending. It can also cause tensile stress if one side of the hoof flexes outward more than the other.
• Compromised laminar connection: The connection between the toe wall and the coffin bone can be damaged by laminitis, white line disease, metabolic problems, inappropriate diet, and mechanical stresses.
• Toe-first landing: Pain in the back of the foot can cause a horse to land toe first in an attempt to protect the painful area. Unfortunately, toe-first landing interferes with the biomechanics of the entire limb and subjects the toe to an unnatural amount of concussion, which can lead to toe cracks.
• Toe loading: A horse that stands with his toes loaded more than his heels due to pain or an issue like a club foot will also be more prone to toe cracks. Horses that travel heavy on the forehand will also tend to stress their toes.
• Overgrown walls: Walls that have grown well past the level of the live sole tend to crack, split, and otherwise fall apart.
• Presence of a crena: A crena is a notch in the center solar margin of the coffin bone, which can sometimes result in a corresponding disruption in the sole-wall juncture that you can see on the bottom of the foot at the center of the toe. This disrupted area gets filled with material that is not as strongly organized as normal material and can sometimes make the hoof wall more prone to cracking.
Treating and preventing cracks
The most appropriate treatment for a crack is going to depend on its location, severity, and cause.
Any contributing disease condition, injury, nutritional problem, or hoof imbalance will need to be addressed if possible, and the mechanical forces working to cause or perpetuate the crack will need to be relieved. In most mild to moderate cases, and even some pretty bad ones, the latter can be accomplished by getting the foot balanced, removing any overgrown wall, and putting a strong bevel on the cracked wall area so that it is free from ground contact forces. Doing this generally negates the need for additional stabilization, though some hoof-care providers prefer to add mechanical stabilization in the form of a shoe or hoof cast.
When a crack is severe, it may require more intensive treatment best performed by a veterinarian or very qualified farrier. They may use a variety of techniques including stainless steel lacing, debridement of infected areas, and patching with special materials.
Preventing cracks from happening in the first place is always better than trying to fix them after the fact. Make sure that your horse doesn’t suffer from “lack of farrier disease,” as overgrown neglected feet are highly vulnerable to cracks.
But, while regular hoof care is one of the most important crack-prevention strategies, just having the feet tended regularly doesn’t necessarily mean they are being tended well. You need to stay on top of the quality of work being done by your provider, as so many cracks are caused by manmade hoof imbalances.
Also take a look at your horse’s diet to see if what is going into his mouth could be setting his feet up to crack. Think about potential hazards like excessive moisture and exposure to repeated cycles of wet and dry. Study how your horse moves and stands, as there could be imbalances or soreness somewhere else in the body that are causing uneven loading that could lead to hoof cracks.
This excerpt from The Essential Hoof Book by Susan Kauffmann and Christina Cline is reprinted with permission from Trafalgar Square Books (www.HorseandRiderBooks.com).
