Causes, Treatment, and Prevention
A quarter crack is differentiated from other hoof cracks by: location (toe, quarter, heel, or bar), depth (superficial or deep), and site of origin (ground surface or coronary band). The hoof crack pictured here is at the quarter of the foot, is deep enough that it involves the sensitive tissue, and originates at the coronary band.
Hoof cracks can be caused by improper foot balance, coronary band defects, excessive hoof growth, thin walls, dry hoofs, or overly moist hoofs. Because improper hoof balance is a leading cause of hoof cracks, the farrier is often blamed. This may be unfair. Many horses get hoof cracks due to genetics; they grow low heels with a long toe and thin hoof walls. The tubules that make up the foot of horses with low heel long toe conformation grow forward instead of downward. The forward growing tubule is not as mechanically strong therefore is not able to stand up to the forces placed on them. Consequently the hoof wall breaks (cracks). Most horses develop hoof cracks while at work when the forces are greatest on the hoof wall. I have however seen rather sedentary horses develop quite severe and painful hoof cracks.
Superficial hoof cracks can be treated simply by balancing the hoof and correcting any extenuating circumstances such as adding moisture to overly dry feet. Some farriers will cut a horizontal groove in the hoof above the crack "to stop its progression upward". This practice is counter indicated. The groove only serves to weaken the hoof wall further. This "treatment" probably gained popularity because when the farrier was cutting a grove into the hoof wall he was also balancing the foot. Proper hoof balance, not a groove stopped the progression of the crack.
Severe cracks are more complicated and often must be treated in several steps. Hoof pain originates from three sources. The vertical force when the horse puts its foot on the ground. Horizontal stress from the now unstable back part of the hoof pinching sensitive tissue when the horse walks. Finally inflammation and swelling from infected soft tissues.
To treat the vertical force we float the heel. This simply means the area behind the crack is trimmed shorter than the surrounding hoof wall so that it does not contact the ground. In this picture , the vertical force has been eliminated. Notice the heel is not touching the shoe. An eggbar shoe is applied to support the healthy hoof.
Infection and inflammation must be controlled before the final stabilization of the hoof can be completed. Infection can be controlled using antibiotics, both topical and systemic. Drawing agents such as Epsom Salt and Animalintex can be used to reduce swelling.
To treat horizontal stress and pinching the crack is debrided often using a motorized Dremel tool. Necrotic, infected and undermined tissue is removed. The unstable back of the hoof is then attached to the more stable front of the foot. Attachment can be accomplished in many ways; the hoof can be laced with wire either embedded in the hoof wall or attached to metal studs drilled into the hoof wall. Farrier Lance Kendrick and I stabilized this foot using a wire lace method.
I often use acrylic hoof compounds to attach the unstable heel. The foot pictured below is a completely repaired quarter crack stabilized with acrylic.
Keep in mind that purpose of attaching the hoof is not so that it can grow together like a skin wound. Rather, it is attached to provide stabilization while healthy tissue grows from the coronary band.
To prevent hoof cracks I suggest performance radiographs (x-rays) of the foot be used to properly balance the hoofs. Using radiographs of the hoof, balance can be achieved based on the internal structures inside the hoof capsule. If the mechanical cause of hoof cracks can be identified and eliminated prognosis for future athletic performance is excellent.
Robert H Koontz DVM
Chief Executive Officer
Conley and Koontz Equine Hospital