dentistry
Focus on
Temporomandibular joint (TMJ)
chewing to findTMJ
The horses were outfitted with a system of LED lights similar to the 3-D motion tracking systems used in movies to map facial movements to follow mastication.
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Images courtesy of Dr. Travis Smith
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disease can often be found toward the bottom of the differential list, but pain from the disease can cause noticeable masticatory derangements and compensation. If left undiagnosed, it may even lead to quidding and anorexia. The pain associated with TMJ disease is also suspected to cause behavioral idiosyncrasies, such as head shaking, shyness, or fighting at the bit, which can make riding difficult or impossible, according to Travis T. Smyth, DVM, BSc, surgical resident at the Western College of Veterinary Medicine in Saskatchewan, Canada. “The issue with TMJ disease in horses is that we don’t really know if the disease exists, or more specifically, how often it exists,” Dr. Smyth said at the 61st Annual Convention of the AAEP in Las Vegas. “The shortage of reported literature artificially suggests that the disease is restricted to a small number of overt or endstage cases, but some research suggests that the inflammation process and degenerative joint disease in the TMJ is similar to other joints.” The researchers wanted to know whether TMJ disease was degenerative, and if so, why it was so rare. They also wanted to know whether some horses suffered less severe disease and therefore, were less painful. The TMJ is referred to as the single most active joint in the horse, so common sense would indicate that the disease would occur with more frequency, he said. “If we’re not seeing it, then either the disease isn’t painful, or we’re not using methods that are sensitive enough to pick it up,” Dr. Smyth explained. To test whether changes in the masticatory cycle could indicate the presence of underlying TMJ disease, Dr. Smyth and his colleagues examined the kinematics of the joint and characterized the movements of the ModernEquineVet.com | Issue 4/2016
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