Healthy Horse Hoof

What do you look for when checking your horse's hooves? What are the major areas of concern? What is going on with my horse's hooves? Almost every horse owner has asked these questions at one point or another. Below are some areas to notice when looking at your horse's hooves:

Trail Horse Hoof Care

• Hoof wall: The hard, exterior "capsule" of the hoof.
• Coffin bone (also called the third phalanx, P3, or pedal bone): The largest, hoof- -shaped bone within the hoof capsule.
• Laminae: Velcrolike tissues within the hoof that suspend the coffin bone inside the hoof wall.
• Blood vessels and nerves: These supply the hoof tissues with critical oxygen and nutrients and remove waste products.
• Deep digital flexor tendon (DDFT): A tendon that attaches to the back of the coffin bone and runs up the backside of the hoof. The deep digital flexor tendon is a large component of how a horse flexes his foot each time he takes a step.
• Frog: The v-shaped, calluslike cushion on the underside of the hoof.
• Sole: The bottom of the hoof.

• Symmetrical or asymmetrical?-If both hooves are not a matched pair it could be do to underlying problems. Uneven weight distribution, tendon tension, pain and lameness could be the culprit.
• Coronary Band - Should be straight with a slight arch upward. A coronary band that is asymmetrical might have sheared heels that can lead to quarter cracks and thrush. A normal coronary band angle is 20 degrees to 25 degrees. If the coronary band angle is greater than 30 degrees there probably is a problem with the palmar/plantar angles which can crush the horse's heel. Conversely, a high palmar angle is often seen in horses with laminitis or horses with club feet. Heel pain, deep digital flexor tendon strain, and/or coffin joint disease can also be caused by improper angles of the coronary band.
• Hair along the coronary band should lie flat.
• Hoof walls should be smooth, light shine, free of prominent growth rings, lack flares, cracks and bruising.

The presence of prominent growth rings can indicate a number of problems, including reduced blood perfusion in the corium (the hoof's dermis, or the middle soft tissue layer that connects the coffin bone to the rigid hoof capsule and contains the hoof's blood supply). resulting from abnormal hoof loading, diet changes, exercise intensity, or systemic disease. Growth rings can also indicate a negative palmar/plantar angle; Taylor said growth rings in these horses are "often wider in the toe region and narrower in the heel region due to uneven blood flow caused by overloading of the heel." Chronic and excessive overloading of the hoof wall also can cause flares or cracks, Taylor said.

Hoof wall bruising is indicative of trauma...and bruises can form near the coronary band when ground reaction force pushes the hoof capsule against the coronary region's vascular (blood vessel-rich) tissue. While some isolated bruises can be caused caused by a single acute event, others-typically seen as a wide band of bruising-are an indication of chronic trauma, such as laminitis...

Frog - The frog is a "highly dynamic" structure that changes in response to terrain and other hoof demands...A frog's width should be approximately 50 to 60% of its length, and the portion closest to its apex (point) should be substantial enough to touch the ground when the horse is bearing weight. "If this portion of the frog does not engage the ground, fibrocartilage in the (rear) of the foot is hypothesized to develop poorly or atrophy, contributing to a weak heel,"...A healthy frog has a shallow central sulcus, wide enough for a ring or index finger to fit...A common frog defect is a contracted (too narrow) central sulcus, which creates an anaerobic (lacking oxygen) environment ideal for thrush development. The central sulcus will remain contracted until the thrush resolves. "When thrush gets in there, the horse may try to avoid using the back of his foot,"...creating a mechanical situation that can predispose the foot to lameness.

Collateral Sulci - When seeking information about potential internal problems...a horse's collateral sulci (the grooves located adjacent to the frog) can be very telling. The sulci run parallel to and remain a fixed distance from the bottom of the coffin bone in the front half of the hoof and the collateral cartilages in the rear half of the hoof. The sulci should be relatively linear and shouldn't undulate in depth. ...many other hoof structures, the depth and contour of the collateral sulci aren't typically altered by hoof care efforts. In a healthy foot, the distance between the ground and the collateral sulci, where they converge at the apex of the frog, is 10 to 20 millimeters, Taylor said. The coffin bone's concave solar surface (located on the bottom of the bone, just above the sole of the foot) sits about 10 to 11 millimeters above this point.

There could be problems when the collateral sulci develop a stair-step or undulating shape and become significantly deeper in the heel...This shape, often found on horses with long toes and "underrun" heels, is likely indicative of poor heel development. She recommended veterinarians perform radiographs on hooves with this conformation to evaluate the coffin bone's position; the palmar/plantar processes of these coffin bones might be dangerously close to the ground, she said. Some veterinarians hypothesize that the negative palmar/plantar angle is associated with lameness in not only the foot but also proximal (higher) portions of the limb. "This conformation in hind feet may be associated with pain in the hocks, suspensory ligaments, gluteal and lumbar regions," Taylor said.

Heel Base - Next, Taylor described the heel base, which includes the hoof wall, buttress (the back the part of the hoof that makes initial contact with the ground from a heel-first landing), sole angle (the degree between the coffin bone and a straight horizontal line), and bars. In a healthy hoof, she said, the heel bulbs shouldn't touch the ground, and the heel tubules should be straight and nearly parallel (within 5°) to the tubules in the toe region. The heel tubules' most palmar (furthest to the rear) weight bearing surface should be at the base of the frog.

Underrun heels - which can be caused by a variety of issues ranging from a horse's conformation to improper trimming and/or shoeing-can lead to an array of problems. "Underrun heels that grow forward towards the widest part of the foot often collapse under the weight of the horse, causing heel tubules to run nearly ground parallel, ...The bars and the angle of the sole may be crushed, deformed, or injured as a consequence of the severely underrun heel."

Additionally,...researchers have recently postulated that inadequate fibrocartilage development in the digital cushion (a soft tissue structure in the hoof capsule, above the frog) is a precursor to tissue injury and lameness. She recommended practitioners become familiar with what a healthy heel looks and feels like. "A sense of normal can be learned by palpating the digital cushions of sound horses with good feet and comparing those findings with those of horses with poorly conformed feet," she said.

In a healthy hoof, the combined tissues of the frog and digital cushion should measure about two inches, she said; hooves with combined tissues measuring less that that will likely be predisposed to injury. Underrun or collapsed heels with underdeveloped digital cushions deform easily when you apply thumb pressure, while healthy heels will not give way as readily. Horses with suboptimal digital cushion volume and fibrocartilage usually have either narrow, contracted or wide, thin underrun heels, and they likely are at risk for lameness...

Hoof Sole - The sole surface should be concave, calloused, and about as wide as it is long, measuring 12 to 15 millimeters thick under the distal rim of the coffin bone, she said. A sole with this thickness can effectively protect the coffin bone from trauma. A simple way to predict sole thickness is by placing a ruler (calibrated in millimeters) in the collateral sulci at the apex of the frog, measuring the distance between the deepest part of the sulci and the bottom of the hoof... Taylor explained that thin-soled horses have very little or no depth of the collateral sulci at the frog apex. Horses with zero collateral groove depth at the apex of the frog generally have a sole depth of less than 7 millimeters, she said, which can predispose them to sole brusing, subsolar infection, and coffin bone remodeling or rim fractures.