Correcting Crushed Heels (Bluegrass Laminitis Symposium)
We've all seen them, and many of us have owned them--those horses with no heels to speak of. We know that "strong" heels are important for soundness, but what can we do to rebuild those crushed, underrun heels? At the 2007 Bluegrass Laminitis Symposium, Richard Mansmann, VMD, PhD, clinical professor and director of the North Carolina State University College of Veterinary Medicine's Equine Podiatry and Rehabilitation Service, discussed the various causes of crushed heels, how to avoid them, and how to treat them.
"We see a lot of chronically lame horses trying to work with long-toe, low-heel conformation," he began. "It's a very common foot conformational problem. The lower the hoof angle, the more stress is placed on the posterior part of the hoof and limb (ideal hoof angles range around 54° in front feet and 58° behind, he noted).
"Affected horses usually have a broken-back hoof-pastern axis and a zero or negative sole plane angle (often called the palmar/plantar angle--the angle the wings of the coffin bone make with the ground; this angle should be positive 5-10° with the rear of the bone higher than the front)," he went on. "They probably also have breakover too far forward (i.e., the forwardmost point of ground contact between the shoe/hoof and the ground is too far in front of the tip of the coffin bone)."
Not Just a Cosmetic Problem
"These horses have a serious, chronic problem that will take long-term, conscientious monitoring and treatment to maximize soundness," stated Mansmann. "The longer the problem has existed, the greater the overall damage to internal and external structures. If the problem is fairly new, you might be able to return to normal (healthy) foot conformation, but you may not be able to re-establish decent posterior digital cushion very quickly.
"I say as long as they've had this problem, that's how long it might take to get them better," he continued. "You need at least three trimmings/shoeings to see if the heels will return to their normal height (start seeing increased heel growth out), and you also need to address problems that might be causing the low heels, such as horse body weight (too much weight can simply overload the feet), diet (does it provide balanced nutrients for good hoof growth?), exercise program (how much does the horse move around on those feet?), turnout, etc. You might also need to reduce total moisture to the feet such as turnout in wet or even bathing of the horse to avoid wet/dry cycling."
Types of Crushed Heels
Mansmann described seven types of crushed heels, ordered from easiest to hardest to treat.
- Heel crushing in one front foot (often called "high/low foot") where the low foot has a sole depth greater than 15 mm, and is less than 1 cm wider than the higher foot (at the widest part of the foot).
- Crushing of heels in both front feet with a sole depth greater than 15 mm.
- Heel crushing in both front feet with sole depth less than 15 mm and zero to negative palmar angles.
- Crushing of heels in both hind feet only (hind feet have zero to negative plantar (palmar out) angles, while front feet have positive palmar angles).
- Crushed heels in all four feet where all four feet have negative sole plane (palmar out) angles and low toe angles.
- Crushed heels in all four feet with low heels, but the feet have different sole and /or horn-laminar zone (hoof wall) thicknesses.
- Chronically crushed front foot with a sole thinner than 15 mm, where this foot has a significantly lower toe angle than the other front foot. "Everyone has worried about the 'club' foot and ignored the low front foot, and it's the one over the years that's not doing well," he commented. This is the category #1 that has aged many years without attention to the flat foot.
"To treat any of these cases, you need consistent lateral radiographs and buy-in and commitment from the veterinarian, farrier, and owner," he said. "It seems that the lower the palmar/plantar angles and the lower the sole depth, the more difficult it is to mechanically relieve the horse's pain."
Treating Crushed Heels
As with many health problems, identifying and treating crushed heels early is critical to treatment success, noted Mansmann. If you wait until the horse has a thin sole and crushed digital cushion, he will need to be shod with mechanics (tailored shoeing to promote proper bone alignment and blood flow) for the rest of his life. The digital cushion does not regenerate well once significantly crushed. Also, structural failure within the foot can lead to chronic pain in the heels, fetlocks, suspensory ligaments, and even the back, when the hind feet have low heels.
Heel wedges are commonly used to raise low heels, but Mansmann warned that this practice can ultimately crush the heels further when used on front feet. The goal is to get the heels growing more, which means redistributing some of the crushing forces elsewhere in the foot so the heels can heal. He notes that moving breakover back can be helpful, as this makes it easier for the horse to lift his heels off the ground when moving.
He offered the following treatment plans for the various cases of crushed heels:
Category 1: High/low foot with healthy sole thickness (15 mm or more).
"This category is one of the easier ones with more options," he said. "We try to make the feet as equal as possible by reducing (trimming out) toe on the low foot and providing good heel support to prevent the flat foot from becoming really crushed and losing internal circulation. We worry about the flat foot, the one that looks 'best.' "
Category 2: Crushing of both front heels with healthy sole thickness.
"These horses are trimmed by just removing toe from the bottom of the thickish sole and taking back the excess toe wall," he said. "If you keep the foot in the right shape, trimming every four to five weeks, you'll stay ahead of the problem."
Category 3: Crushed heels in both front feet with less than 15 mm of sole and zero to negative palmar angles.
"This is the most common category I see," Mansmann commented. "These horses could be intermittently lame for weeks, months, or years. They're sore in the heels, but have minimal bone problems. We use thick aluminum shoes with breakover moved to the center of the shoe ('floating' the back of the foot when it's flat on the ground, making it very easy for the horse to tip his weight forward and lift his heels, creating an 'air wedge' for his heels). We also use a pour-in pad for sole and frog support and to reduce concussion on the sole."
Category 4: Low heels in both hind feet.
"Affected horses can have other hind limb and back issues (because the low hind heels place additional strain on the upper limb, pelvis, and lower back)," he noted. "They get sore heels, sore high and low suspensory ligaments, sore fetlocks, sore hocks (hock injections only work for a few weeks), sore backs, and decreased performance or lameness.
"We move breakover back and consider raising heels on horses with zero to negative plantar angles," he said. "This helps reduce back soreness for many horses. In some more severe cases we use a squared-toe shoe set back with quarter clips and wedged pad. I feel a wedge does not crush the heels behind as it can in front due to less 'body weight' on the hind heels."
Categories 5 and 6: Crushing of heels in all four feet.
"We think it's tough to get these horses back to routine soundness," Mansmann noted. "You can have success with major buy-in and plenty of supportive treatment (a combination of the front and hind feet shoeing previously described).
Category 7: Chronically crushed front foot with a sole thinner than 15 mm.
"This foot is the #1 scenario gone bad," he explained. "The low heel has been low, and lowering, for years and not addressed. Was everyone worried about the club foot? It's the healthier foot! Treat the flat foot like our Category #3, but if there is no increase in sole depth with a shoeing, a venogram to evaluate blood flow to the foot might be in order.
"Treating low heels is always a work in progress," advises Mansmann. "We can improve horn quality of the heels and hoof mass, and we can generally improve sole thickness 2-4 mm per shoeing to a total of 15-25 mm. By mechanically making the hoof-pastern axis normal, we make many horses sounder.
"However, we have not been able to redevelop mass in the digital cushion area in horses that have zero to negative palmar angles and thin soles," he reported. "They need mechanics continuously; if you take them back to a flat shoe, they get back to the thin sole and sore heel again."
Working to correct low heels when they begin to develop is far more successful than waiting until the horse has had no heel for a long time. Low-heeled conformation is not healthy and can compromise soundness in the short or long term.
About the Author
Christy West has a BS in Equine Science from the University of Kentucky, and an MS in Agricultural Journalism from the University of Wisconsin-Madison.
POLL: University Equine Hospitals