Smyth T T, Carmalt J L, Treen T T, Lanovaz J L
Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada.
College of Kinesthesiology, University of Saskatchewan, Saskatoon, Canada.
Equine Vet J. 2016 Jul;48(4):523-7. doi: 10.1111/evj.12452. Epub 2015 Jun 18.
Diseases of the temporomandibular joint (TMJ) are well reported in man and some domestic animals other than the horse. The pathophysiology of equine TMJ disease and the effects of disease on the kinematics of mastication are unknown.
To determine whether transient unilateral inflammation of the equine TMJ results in alterations in the masticatory cycle.
An experimental controlled study utilising 6 horses of various ages with normal dentition.
Each horse was equipped with an optical motion tracking (kinematic) system. Horses were observed chewing grass hay over 3 min intervals. Regardless of the initial side of the power stroke in the masticatory cycle, lipopolysaccharide (LPS) was injected in the left TMJ in each horse and the horses were reassessed after 6 h.
Four horses developed effusion of the injected TMJs; 2 of these also began quidding. All horses injected on the original side of the power stroke switched sides while the 2 injected on the contralateral side did not. All horses developed reduced vertical pitch (vertical opening) of the mandible. Overall, rostrocaudal movement of the mandible did not change; however, the timing of this movement relative to the phase of the masticatory cycle did. Injection with LPS did not affect the amount of lateral movement of the mandible.
Injection of LPS into the TMJ significantly altered the masticatory cycle compared with baseline values representing avoidance behaviour due to inflammation of the joint, despite which the horses continued to eat using the contralateral mandible. Lipopolysaccharide administration also led to quidding and a loss of feed efficiency (in some individuals).
颞下颌关节（TMJ）疾病在人类和除马以外的一些家畜中已有充分报道。马颞下颌关节疾病的病理生理学以及疾病对咀嚼运动学的影响尚不清楚。
确定马颞下颌关节的短暂单侧炎症是否会导致咀嚼周期的改变。
一项实验对照研究，使用6匹不同年龄、牙齿正常的马。
每匹马都配备了一个光学运动跟踪（运动学）系统。以3分钟的间隔观察马咀嚼干草的情况。无论咀嚼周期中动力冲程的初始侧如何，每匹马的左颞下颌关节都注射脂多糖（LPS），6小时后对马进行重新评估。
4匹马注射的颞下颌关节出现积液；其中2匹还开始出现咀嚼不全。所有在动力冲程原始侧注射的马都改变了咀嚼侧，而在对侧注射的2匹马没有改变。所有马的下颌骨垂直间距（垂直开口）都减小了。总体而言，下颌骨的前后运动没有变化；然而，这种运动相对于咀嚼周期阶段的时间发生了变化。注射LPS对下颌骨的侧向运动量没有影响。
与代表因关节炎症而产生的回避行为的基线值相比，向颞下颌关节注射LPS显著改变了咀嚼周期，尽管如此，马仍继续使用对侧下颌骨进食。给予脂多糖还导致咀嚼不全和饲料效率下降（在一些个体中）。
