Few subjects are as controversial as the cause of quarter cracks. Some farriers insist, “Quarter cracks are always caused by improper shoeing!” Other farriers flatly deny this and point to factors in environment, heredity and injuries to the coronary band and hooves.
In reality, while several factors predispose a horse to quarter cracks, the most preventable ones are related to trimming and shoeing, with incorrect balance of the hoof topping the list. A properly balanced hoof works to even out the pressure on that hoof wall. Pressure, especially uneven pressure, can lead to hoof cracks.
When a seasoned farrier watches your horse walk, he’s sizing up many factors, including the relationship of the foot to the pasterns, cannon bone, and shoulder angles, growth patterns, depth, width and height of the foot, and how and when the foot breaks over with each step. A horse that possesses ideal conformation and has a foot that lands evenly each time it touches the ground is a blessing of balance for the rider and the farrier.
A hard-to-balance hoof can be a challenge, especially when conformation problems are involved in a mature horse. Horses that toe out, or are base narrow, won’t land evenly, placing a lot of concussion and stress on certain areas of the hoof because the impact of weight isn’t evenly distributed. A big horse with a tiny, steep foot is not a good combination. There is less area to absorb the concussion when the hoof lands.
“The stress is concentrated over a smaller area when you have a smaller foot,” said Christian Rammerstorfer Ph.D., PAS, Equine Exercise Physiologist/Nutritionist, Oregon State University. He rides reining horses. When he looks at a two-year-old prospect, he pays close attention to conformation, of course, but his eyes also go right down to the horse’s hoof.
Flares in the hoof, often the result of lack of regular farrier care, can eventually cause quarter cracks. The hoof takes on an asymmetric shape from the flares in the wall. Functionally, it’s out of balance and the weakness predisposes a horse to cracks. Horses with flatter feet are more susceptible to flares.
“The flare itself makes the wall thicker, but a lot less dense. It spreads apart the horn tubules. While it will appear thicker to the naked eye, looking at it under a microscope will show that the spread of the horn tubules weakens the hoof wall tremendously,” said Rammsterstorfer.
Other quarter-crack causes include actual farrier shoeing mishaps:
• Using nails that are too large for the size of the foot
• Driving the nails improperly, too far back on the hoof itself.
Quarter cracks can also result from an injury to the coronary band, such as a wire cut. With this type of injury, it’s possible the quarter crack can be managed and maintained but will never go away. Certainly, the amount of time it takes for this type of crack to grow out is the longest.
Whatever the cause, the fact remains that quarter cracks aren’t to be ignored. They can result in long lay-up times and can be painful to your horse. There’s no way to predict the amount of time your horse could be out of service. Following the advice of a qualified farrier and your veterinarian can be crucial.