Hoof wall defects are common in sport horses presenting with lameness and loss of use. Successfully managing these horses requires an understanding of why the hoof wall cracks, said Stephen O’Grady, DVM, MRCVS, of Virginia Therapeutic Farriery, in Keswick, during his presentation at the 2024 American Association of Equine Practitioners Convention, held Dec. 7-11, in Orlando, Florida.

Why Do Quarter Cracks Occur in Horses’ Hooves?

Quarter cracks in the hoof arise from overloading one side of the horse’s foot, generally the inside—toward the midline. “You won’t see a quarter crack without hoof capsule distortion,” said O’Grady. “And that distortion is going to be caused by an asymmetrical landing, where the lateral (outside) side of the horse’s foot contacts the ground first, then overloading the medial (inside) aspect of the foot. Over time, when the hoof wall can no longer take the excessive loading, it cracks.”

Hoof capsule distortion means the capsule changes shape from what is considered normal or healthy. That distortion relates to the horse’s conformation and how the foot lands on the ground.

Most horses with hoof capsule distortion have a rotational deformity, which means the bone alignment is straight, but they have a narrow chest, and their limbs rotate laterally.

Corrective Shoeing for Quarter Cracks in Horses

“Again, if you have a quarter crack, you have a distorted foot,” said O’Grady. To manage this, take the shoes off for 10 to 14 days and trim the heels so the heels and frog are on the same plane.

“Once everything is on the same plane, there is load sharing by all the structures, and the heels drop down and relax,” O’Grady said. He typically puts a spider plate on these horses. This shoe type protects the heel and redistributes the load to the lateral aspect of the foot.

O’Grady also recommended moving the shoe laterally with an extension. “The shoe can be placed tight or flush on the medial side but then has a one-quarter- to three-eighths-inch extension on the lateral side,” he said. “This moves the center of pressure to the better side of the foot.”

Take-Home Message

Hoof wall defects, such as quarter cracks, can lead to lameness in horses, especially if left untreated. Quarter cracks occur when a horse unevenly loads one side of the hoof as he travels. Farriers can manage quarter cracks using corrective trimming and shoeing, which can help balance the pressures placed on the hoof.