Coronary Band Injuries in Horses
While bringing him in from the pasture, Boogie's owner noticed blood trickling from the Quarter Horse's coronary band and down his left front hoof. Once inside the barn, she immediately went to work cleaning and dressing the wound, then called in a veterinarian to inspect the injury. The veterinarian declared the injury superficial. He suspected Boogie probably sustained the injury when a pasturemate stepped on his foot. He cleaned and sutured the wound, then ordered the animal barn-bound while the wound healed.
Boogie's injury could have been much worse. A deeper coronary band injury would have required more extensive care and could have affected the horse's long-term soundness.
The coronary band is located where the hairline meets the hoof capsule and is the structure responsible for approximately 70% of hoof growth. Horses' hooves grow an average of ¼ inch per month, according to Robin Dabareiner, DVM, PhD, Dipl. ACVS, assistant professor at Texas A&M University's College of Veterinary Medicine & Biomedical Sciences. She adds that hooves completely regenerate every eight to 12 months, on average.
"Damage to the coronary band usually results in slow and abnormal hoof growth," Dabareiner says.
Types of Injuries
Lacerations that extend from the pastern region through the coronary band toward the back of the foot are the most common coronary band injuries, according to Dabareiner. These so-called "heel bulb" injuries generally occur when horses step on one another's feet during pasture play. But horses also sustain similar injuries when their feet become entangled in barbed wire in their pastures, or when their feet get caught under fences or metal sheds. On the trail, debris and sharp rocks put horses at risk for coronary band injuries.
Horses that overreach when performing their gaits are particularly at risk for coronary band and hoof wall injuries. So are horses that perform in certain disciplines, says Daniel J Burba, DVM, Dipl. ACVS, professor of equine surgery at the Equine Health Studies Program in Louisiana State University's School of Veterinary Medicine.
"Barrel horses and jumping horses, for example, are vulnerable because they're moving at high speed and doing a lot of twisting and turning," Burba says.
An owner whose horse sustains a coronary band laceration should call a veterinarian as soon as he or she notices the wound. While waiting for the veterinarian to arrive, the owner should gently wash the wound with water, apply a clean gauze bandage to the injured area, and place the horse in a clean stall to await treatment. Follow appropriate bandaging steps, recommends Amy Rucker, DVM, of Midwest Equine in Columbia, Mo.:
- Clean the horse's entire foot, including the sole.
- Pad the arteries and veins with a wad of cotton balls or gauze. (Think of the front of the foot as 12 o'clock; the arteries and veins will be located at 4 and 8 o'clock on the back of the pastern.)
- Wrap a self-adherent bandage (such as Vetrap or Co-Flex) under the heel bulbs and work upwards; the heels will hold the bandage down so it doesn't slide up the pastern. Make sure the bandage is snug but not too tight.
- If the horse is not in a pristine environment, construct a square of duct tape approximately one inch wider than the widest part of the horse's foot, fill the bottom of the foot with cotton balls, and apply the duct tape. This is also a good practice for heel and heel bulb lacerations or for horses in wet stalls or mud.
Veterinarians treat coronary band wounds by first determining the depth of the laceration and whether debris is lodged under the hoof wall.
"We always worry about the depth of the wound and whether the coffin bone or the pastern joint have been affected," Burba says.
Injuries deep enough to cause damage to those structures can result in long-term lameness and the development of other complications, such as osteoarthritis, that affect soundness. Some horses that sustain wounds deep enough to damage bone structures and tendons and must be euthanized.
After veterinarians assess the severity and depth of the wound, they wash the injured area with a povidone-iodine or iodine (Betadine) scrub and sterile water and remove any remaining debris or unhealthy tissue surrounding the wound.
"If the wound is less than six hours old and not very dirty, it can be sutured," Dabareiner says. "Since it is a very mobile area, a foot cast can be applied to minimize movement until the wound and coronary band are healed. This takes about three weeks."
Wounds more than six hours old or those that are very contaminated are cleaned, covered with a hoof bandage, and allowed to heal on their own. Veterinarians might administer systemic antibiotics if the wound is extremely contaminated, says Dabareiner.
Active horses also are at risk for hoof avulsion injuries. These are wounds that pull the hoof from the lower limb. Hoof avulsion injuries occur when a horse's foot is cut through the entire coronary band and hoof capsule, usually after it has been caught under an object.
Veterinarians treat these injuries by removing the damaged hoof wall and cleaning the wound. They then work with the horse's farrier on a long-range treatment plan, Dabareiner says.
"The area under that damaged wall is trimmed shorter than the rest of the foot so that it does not bear any weight. This gives the damaged area time to heal properly and (the area) doesn't hurt since it is not bearing weight," she says. "But if that part of the hoof is not bearing weight, we have to add a special horseshoe that will protect the damaged area as the hoof wall grows back and takes up the weight bearing that is missing."
According to Jason Wilson-Maki, CJF, RJF, Dipl. WCF, resident farrier at Texas A&M, the shoe applied to treat hoof avulsion injuries--designed to compensate for the horse's inability to bear weight on the injured area--contains one or more bars, de-pending upon the severity and location of the injury. The full support shoe allows the horse to stand on the good or undamaged part of the foot while the damaged aspect of the hoof heals.
"Think of the foot as a 270-degree circle, including the hoof wall," Wilson-Maki says. "If the foot cannot bear weight, we basically need to provide a base to carry that weight load and prop up the damaged tissue."
The supportive shoes used to treat hoof avulsion injuries are constructed with either a single bar placed at a diagonal across the shoe or with a pair of bars that cross each other diagonally from one side of the shoe to the other, forming an "X" configuration. The severity and location of the injury dictate whether a single bar, or an "X-bar," shoe is applied to the injured hoof.
Farriers treat hoof cracks resulting from coronary band injuries by using clips to secure shoes to the hoof wall. Farriers and veterinarians might have to use acrylic compounds, staples, or other devices to close very severe cracks and support the outer hoof wall while new hoof material develops.
As healing takes place, farriers perform follow-up treatments such as trimming the hoof and replacing shoes.
According to Wilson-Maki, both initial and follow-up treatments should be a collaboration between a veterinarian and an experienced farrier. Ideally, a veterinarian and a farrier would both be on hand to examine the injury and create a longer-term treatment protocol.
Most horses that sustain hoof avulsion injuries recover complete soundness under appropriate immediate and long-term care, Dabareiner says.
"But almost always there will be a hoof defect at the site of injury," she adds.
Horses with injuries that do not involve damage to the coffin bone or pastern joint are usually very likely to return to their previous athletic soundness, according to Dabareiner. However, even shallow injuries can result in some long-term effects if they involve a large portion of the coronary band. Between 1988 and 1994 Dabareiner and others studied the long-term effects of heel bulb lacerations on 101 horses. Results revealed that while 90% of the horses involved in the study survived their injuries, 18% of those survivors showed long-term abnormalities in hoof wall growth.
Aside from lacerations and hoof avulsion injuries, abscesses are also common causes of coronary band injuries.
So-called "coronary blowouts," or "gravel," are abscesses caused by loose hoof nails, rocks, or construction nails that penetrate the horse's foot through the sole. Solar bruising (of the soft tissues between the sole of the hoof and the coffin bone) also can cause this condition.
Abscesses generally drain from the bottom of the horse's foot, Dabareiner says. But when horses' hooves are extremely hard, such as during periods of hot, dry weather, abscesses are more likely to track up the hoof wall, generally between the sensitive and nonsensitive lamina of the hoof, and break through the softer coronary band.
"To treat a coronary band blowout, the owner needs to clip the hair at the break-out site, wash the wound daily, and apply an antibiotic ointment to the area," Dabareiner says.
Owners are not usually at fault when their horses sustain coronary band and hoof wall injuries. But there are steps owners can take to minimize their horses' risk.
First and foremost, according to Burba, make sure pastures and turnout areas, as well as barns and stalls, are free of debris.
"It's important to manage where horses live," he says. "Owners should make inspections of pastures and other turnout areas and barns to be sure these areas are free of metal or other debris that can injure horses."
Owners can also reduce risk for coronary band and hoof injuries by mending damaged fences, removing all displaced fencing material, and electrifying fencelines to keep horses away. They should be sure pastures are free of any farm equipment horses might be tempted to ¬investigate.
"Horses are curious," Burba says. "They want to explore whatever is in their pastures, so it's easy for them to get a foot caught in farm equipment or some other obstacle."
Owners can further protect their animals by placing bell boots on their horses' feet before turning them out into the pasture or trailering them. When trailering, also make sure shipping wraps extend down over the coronary band.
Burba recommends horses that perform disciplines such as barrel racing and obstacle jumping wear bell boots to minimize the risk of training- and competition-related injuries.
Finally, according to Wilson-Maki, horses whose hooves are not properly balanced or are inappropriately trimmed or shod are particularly at risk for foot and hoof injuries. So he advises owners to make sure their horses receive regularly scheduled trimming and hoof care from a professional farrier.
"Owners can't always prevent their horses from (sustaining) injury," Wilson-Maki says, "but consistent, professional farrier care is critical to helping horses recover from or avoid foot-related injury."
Horses are likely to sustain coronary band and hoof wall injuries at one time or another. These injuries can carry long-term performance and soundness consequences. An owner should consult a veterinarian as soon as he or she notices a horse is injured and should work with the veterinarian and farrier on the best treatment plan for a positive outcome. Owners also should rid pastures and barns of obstacles that put their horses at risk for injury.
About the Author
Pat Raia is a veteran journalist who enjoys covering equine welfare, industry, and news. In her spare time, she enjoys riding her Tennessee Walking Horse, Sonny.
POLL: University Equine Hospitals