When racehorses are about 2 years old and start training, they can get tiny stress fractures and new bone growths in their legs. About 70% of the animals have this issue, known as bucked shin, which causes pain and delays in training plans.

The research team from Doshisha University, Nagasaki University, and the Japan Racing Association Equine Research Institute came up with a way to use ultrasound to check for bucked shin. This method was published in The Journal of the Acoustical Society of America.

Bucked shin can be identified with X-ray radiography, but a detailed assessment of the severity requires computed tomography and magnetic resonance imaging (MRI) studies. Large animals present a challenge for these techniques, particularly in the outdoors. Horses need anesthetic and must be lying down.

Human osteoporosis is widely studied via axial transmission, in which an ultrasonic emitter and receiver are put on the skin to produce and monitor wave velocities. The method could make it easier to find bucked shin and keep young horses healthy and able to grow.

“If we can identify this disease at early stages,” says author Mami Matsukawa, “we can stop training for a period of several weeks or have the horses do light training while they recover.”

Matsukawa and her team produced numerous 3D digital models of a racehorse metacarpal bone with various degrees of bucked shin in order to complete this mission. Every single one was based on CT scan measurements of an actual bone with a bucked shin.

When the researchers simulated the propagation of ultrasonic waves along the bone model, they discovered two primary wave components traveling at two distinct speeds, one faster and one slower. Because of abnormalities in the bone, the fast waves altered speed substantially in the area with bucked shin, although the slow waves were largely unaffected.

“We use these velocities of the waves to judge if there is a bucked shin or not,” adds the author. “In an area with bucked shin, there is a new bone formation. If you touch your leg, most likely it is very smooth and there are no irregularities. But if there was some new bone formation, you would find some irregularities in the shape that change the fast wave speed.”

According to the models, there is more fluctuation in the fast waves the larger the area of bucked shin. The axial transmission method has been proven effective for people, so adapting it to work for horses shouldn’t be too challenging. Such ultrasound devices would be inexpensive, portable, tiny, and lightweight compared to current approaches.

In this study, they used only velocity as a diagnostic tool.

In the future, however, the team hopes to use other wave properties, such as modes and attenuation, to find out what bone is made of.

Image Credit: Getty

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