Any fissure in a horse’s hoof wall is a concern. Hoof cracks usually mean there’s some abnormal stress occurring, and ignoring little cracks can lead to bigger, more-worrisome cracks.
Cracks and chips—whether problematic nail holes, surface chips in barefoot horses or serious full-thickness quarter cracks—are basically the result of the hoof lacking normal moisture and elasticity. While genetics do play a role, some management and nutritional changes can help control or correct the problem.
Start, of course, with regular trimming. Six weeks is a good rule of thumb, but if your horse is chipping, call the farrier sooner. Monthly trims for a horse with hoof cracks can be money well-invested.
Most cracks are vertical (in line with the long axis of the leg), but horizontal cracks also occur. Hoof cracks can be found any place around the hoof, start from the top, or bottom, and may or may not cause lameness.
Hoof cracks can occur due to:
- Poor farrier care,
- Poor management,
- Poor nutrition,
- Poor conformation,
- Hard work over hard or rocky terrain,
- Old abscess or injury,
- Coffin bone problems,
- Excessive pawing, and
Most hoof cracks are stable and not painful, but they can worsen, leading to infections and/or hoof loss.Organisms can use those breaks in the hoof wall to invade the inner tissues, which can result in huge farrier and veterinary bills, in addition to pain for the horse.
The Hoof Wall. The hoof wall is made of layers: the stratum externum, stratum medium and stratum internum. The stratum externum is a thin barrier that starts at the top of the coronet band and runs down to the bottom of the hoof. The stratum medium, the strongest and thickest layer, contains the pigmented and unpigmented hoof wall. The stratum internum contains the laminae and vascular layer surrounding the coffin bone.
The hoof is made mainly of keratin, which is a protein. Its stiffness varies from soft (found in skin) to medium (sole and frog) to hard (hoof wall).Keratin in the hoof wall is arranged into tubules, which are straw-like structures running parallel to the hoof wall. The space between the tubules is also packed with dense keratin.
Keratins get their strength from sulfur bonds, mainly the amino acids methionine and cysteine. Genetics dictate the type of keratins deposited in the hoof wall, but the horse’s dietary intake must supply sufficient methionine in order for it to develop (see nutrition sidebar at end of article).
The hoof wall also contains fatty substances and waxes, which form a “permeability barrier” that’s essential to managing the moisture in the hoof.Their job is to keep moisture and organisms out, while trapping the hoof’s natural moisture inside.
The hard external horn naturally has the lowest moisture level.Moisture levels rise progressively from the hard outside hoof wall into the more flexible layers. The fats and waxes that form the permeability barrier are essential to maintaining this correct balance of moisture in the various layers of the horse’s hoof.
Types of Cracks.Sand cracks are basically thin superficial vertical cracks in the wall. They’re usually not of concern. However, they do have the potential of becoming deep, so they warrant attention. Horizontal cracks are usually the result of an abscess breaking out of the hoof wall.
Actual wall cracks are usually deeper and wider. These are the problems you’ll see caused by hoof flares (usually due to infrequent or improper farrier care, although some horses are more prone to flares due to their conformation) or unbalanced feet (again, poor farrier care). The trim or lack thereof puts abnormal stresses on the hoof wall.
Obviously, dry, brittle hooves crack more easily than healthy hooves. If your farrier mentions that hoof dressing might be a good idea, by all means, do so. Most farriers only recommend it when needed, as we’ve all seen hooves made too soft by excessive use. Remember, when applying hoof dressing the hoof only absorbs moisture through the coronary band, sole and frog.Painting it on the hoof wall just makes the hoof dressing manufacturer richer. Shopping note: Some products contain agents that can damage and dry out the feet.Acetone and alcohol are major offenders, so avoid any product that contains them.
Locations of Cracks.Cracks occurring in the rear half of the hoof are called quarter cracks, unless they are at the point of the heel where they are called heel cracks. Cracks located at the front half of the hoof are called toe cracks. Quarter cracks tend to be more worrisome, as the heel takes a lot of pounding that can lead to the loss of a chunk of hoof.
Toe cracks may be caused by conformation problems, like abnormal coffin bone angles. Even imperfect leg conformation can cause uneven stresses and cracks.
Often long pasterns accompany low-angled hooves, causing the front of the hoof to extend too far ahead of the leg. This creates excessive leverage, which exerts extreme force on the inside of the hoof wall, creating the crack.
When a hoof has an abnormally high coffin-bone angle, the hoof will land toe first, which also puts excessive force on the inner hoof wall, creating cracks. Shoeing to cause the heel to land first and a rocker toe reduces those stresses.
Chronic toe cracks can also be caused by a condition known as pedal osteitis. This is a deterioration of the coffin bone that causes notches to form on its margin. These notches reduce the hoof wall’s stability, creating places for it to crack. Shoes will stabilize the hoof wall.
Keep toes trimmed short, using rolled or rocker toe shoes, and hoof patching to manage these cracks. Side clips on the horseshoe will provide stability to the over-flexing hoof wall and allow the crack to grow down the hoof until it’s gone.
Patching the crack in your horse’s foot is usually best done by a farrier, but you can attempt it yourself as well, using the SBS Hoof Crack Kit (see our review here).A note of caution, however. In order to use this kit effectively, you will have to ensure absolute care to follow the instructions precisely.Cleanliness is imperative, as the fill must be able to stick to the hoof.
If you prefer to keep your horse barefoot, and the crack isn’t considered severe by your farrier, he or she may make a notch in the hoof to stop its spread or even burn a notch above it. This helps change some of the abnormal forces causing the crack, sometimes stopping it from spreading, so it can simply grow down and away.
Quarter cracks are commonly caused by conformation defects or hard work (such as a racehorse). Whether due to a rotational defect or a boney misalignment, cracks will appear in predictable places.For instance, a toed-out foot with a base-wide stance will usually develop a medial crack. If you drop a plumb line down from the front of the horse’s shoulder, it will point to the crack. The opposite is true for the toed-in base-narrow horse. Proper balancing of the hoof and shoeing will manage or prevent these cracks. Suturing or a glued-on patch will stabilize these cracks. Often a bar shoe with strategically placed clips is applied to add stability to the hoof wall.
Heel cracks are usually caused by shoes that are too short for the hoof. In this situation, the heels lack needed support and crack from the pressure exerted on them. Trimming the hoof so that the heels are brought back to the widest part of the frog and proper-fitted shoes usually helps cracked heels.
Horizontal cracks are almost always caused by the exiting of an abscess that originated in the white line. Usually a small pebble that was previously embedded in the white line becomes an abscess and the pressure from the abscess causes a hole in the hoof further up the hoof wall. By the time you see this crack, the abscess has run its course. The horizontal crack will eventually grow out, but the hoof will have a weakened area under the crack. Hoof repair materials can be used if the damage is extensive.
Bottom Line. Small superficial cracks can occur due to changing moisture conditions and are usually not a problem but should be monitored. Application of Tuff Stuff may help reduce superficial cracks, especially for horses in wet ground. A good hoof dressing may also help prevent superficial cracks, especially on dry hooves.
Remember that cracks caused by conformation defects are a predictable chronic problem that can be managed with balanced trimming and proper shoeing.Cracks caused by abscess or injury are temporary in nature and can be managed with proper farrier procedures. The only cracks that cause major problems are usually the ones that are ignored too long and those that occur due to an injury to the hoof. Keep your farrier schedule at every four to eight weeks.
Article by Contributing Farrier Editor Steve Kraus.