Earlier today news was released about the disappointing retirement of champion three-year-old Thoroughbred Big Brown. This post will give some background into the type of hoof injury that forced this decision, for those unfamiliar with foot anatomy and injury.
(Double click on photo for a much larger detail view.)
A horse's heel bulbs are similar to the fleshy part of the palm of your hand above the wrist, at the base of your thumb. The bulbs are in the back part of the foot, above the hairline and below the "waist" of the pastern. In this photo, which shows a foot cut in half, it is the brownish zone at the right that bulges out from the hoof. The heel bulbs are comprised of soft tissue, namely the digital cushion, a fat-cartilage mass that fills out the foot and provides multiple cushioning, circulation-enhancing and/or structural functions in maintaining the integrity and strength of the foot. The bulbs are covered with skin and hair and are not protected by hard hoof wall or sole. They are a vulnerable structure. (Photo courtesy of HorseScience.com)
This horse's injury is to the horn-covered heel area just below the skin and hair covered heel bulbs area. The height of the horse's heels and the shape of the bulbs vary from horse to horse.
This stakes horse at Keeneland suffered a heel injury that might have been similar to Big Brown's. Technically the heel bulbs are the area covered with hair, just below the horseshoer's thumb. The area was filled in and covered with acrylic and a glue on Polyflex shoe was applied by Curtis Burns.
This photo was taken when the horse was well into the healing process. Sometimes the hind shoe scrapes down the back of the pastern over the heel bulbs and ripping off part of the heel or pulling off the front shoe. Thoroughbred racehorses frequently suffer from a grabbed quarter, heel bulb lacerations and coronet bruising and cuts because of toe grabs on their shoes. But, as Big Brown showed today, these injuries can occur even without toe grabs; he was not wearing any front shoes at all today.
Frequently a hind foot comes up and strikes the front foot when there is a gait abnormality, such as when horses are galloping on soft turf and the front foot stays on the ground a fraction of a second too long and the hind foot comes forward and strikes it. The injury frequently happens when horses scramble out of the starting gate, and can happen to hind feet when "clipping heels" with another horses.
Some horses have conformational or coordination problems that designate them "hitters" and suffer from chronic lower leg and hoof cuts and bruises and soreness. They usually wear bandages and bell boots when working and have their hind shoes "set back" to reduce the chance of injury when training. Big Brown wore bell boots when schooling for the Belmont to protect his quarter crack patch.
One of Big Brown's feet in the spring of 2008: His heel bulbs are partially recruited into the hoof wall repair for his heel separations. (Ian McKinlay/Tom Curl photo)
How bad can a heel bulb injury be? This is a case at the Rood and Riddle Equine Hospital's Podiatry Clinic, as featured in issue #79 of Hoofcare and Lameness Journal. Dr. Scott Morrison reconstructed the frog and over time, was able to restore the foot and the young Thoroughbred began its racing career wearing normal raceplates. Heel bulb injuries are common around farms, particularly wire cuts, horses catching a hoof in a cattle guard, pasture injuries, trailer loading mishaps, etc.
Aftermath of a heel bulb laceration: This ex-racehorse shows evidence of a severe injury earlier in its life. The horse is completely sound.
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