Just days before it was reported July 12 that California Chrome would miss at least three months of racing because of a cannon bone bruise, Larry Bramlage talked about that type of injury at the Welfare and Safety of the Racehorse Summit July 8 at Keeneland.
Dr. Larry Bramlage - Anne M. Eberhardt Photo
At the summit Bramlage said that as horses get older, the cannon bone can become dense to handle the stresses of racing, which can make the bone more susceptible to bone bruising. The respected equine surgeon and partner at Rood & Riddle Equine Hospital also explained that the term "bone bruising" has become a bit of a catch-all term for vets. He said perhaps more specific diagnoses will be available down the road.
Bramlage explained how a horse's body adjusts to handle racing. Where possible the cannon bone grows wider to handle the stresses of racing. But near the joints bones do not have that option because such growth would interfere with proper joint structure. To increase strength in these areas, the horse's bones will fill in with added bone material.
"There's only two ways to make the materials stronger, you can make it bigger or you change the material to make it stronger. That's where the bones get denser, and denser, and denser to where they approach something like porcelain," Bramlage said. "A normal distal cannon bone is trabecular (spongy)—it has a lot of lacy looking bone on the inside. ... If you need additional strength, the horse only has one option—they fill in those spaces. So the bottom of the cannon bone becomes thicker and thicker. So then it becomes more brittle. Then it becomes less flexible and then it bruises easily."
That said, Bramlage acknowledged current diagnoses of "bone bruising" may be lumping together multiple issues.
"The diagnosis of (the moment), whatever we call this current period of time, is bone bruising," Bramlage said. "Bone bruising gets talked about all of the time. First of all, we can diagnose it better than we used to be able to because we have the digital radiography, the nuclear scintigraphy, MRIs—ways of looking at it. We understand the physiology better than we used to.
But like all diagnoses and all treatments in veterinary medicine, there's a cycle. We learn that something happens or we learn that something works, and we use it on a few things. When we realize it works, we use (the diagnosis) on everything. That's the diagnosis of bone bruising. We learned that it was there, so now we call everything bone bruising."
Bramlage said problems under the "bone bruising" umbrella typically trace to bones that have become less flexible.
"Maybe by 2020 we'll truly understand that terminology (bone bruising)," Bramlage said, before later adding, "(Bones) do get so strong that they sometimes become vulnerable to the pounding."