Shoe horses long enough, particularly performance horses, and you’ll eventually run into a problem with interference.

Two accomplished farriers — Marcus Lybarger of Venice, Fla., who also works in the Chicago area, and Tim Cable, who splits his time between Buffalo, N.Y., and Wellington, Fla. — shared their knowledge to help you meet the challenge. Lybarger shoes hunters, jumpers and dressage horses, while Cable does about 75% of his work with Standardbred horses, the rest about shoe horses. He travels to Kentucky, Connecticut and Canada to work the circuit.

Interference is broadly defined as one of the hooves touching any part of another limb, altering the horse’s gait in a negative way, but both Lybarger and Cable emphasize the various types of interference.

Front limbs. Interference between the two front limbs generally occurs when one of the legs “wings in” and the hoof contacts the opposite shin. In a show horse, the contact typically happens low on the shin because of the controlled, trotting pace. On a racehorse, the hoof can contact the opposite leg anywhere from above the knee into the forearm or down onto the lower part of the shin. For racehorses, particularly Standardbreds, the worst interference is a hoof hitting the opposite knee while the knee is extended.

“That causes a horse to be foul-gaited in the turns and costs a lot of time, and it can even cause them to break their stride,” Cable says. “If the knees aren’t protected or if the interference isn’t resolved…