Imaging findings of the temporal mandibular joint (Tmj) in sport Horses: “a silent enemy”

Introduction

The TMJ is an incongruous and complex joint which can be associated with decrease performances and clinical signs when affected. Clinical signs displayed by horses with TMJ disease include difficulties with mastication, pain when opening the mouth, effusion, headshaking, and refusal to accept a bit when being ridden. The objective of this study was to describe the imaging findings of the TMJ in healthy horses and to evaluate potential differences between equestrian disciplines and age.

Material And Methods

50 clinically normal horses were evaluated in this study (n=100 joints). They were allocated in five groups: control I (24 years-old); III (dressage), IV (jumpers), V (polo). All horses were evaluated clinically by mouth movement and signs of pain, TMJ effusion or inflammation. Subsequently, both TMJ joints were evaluated with radiographs (70º tangential view) and ultrasonography. Shapiro Wilks normality test and Barlett homoscedasticity test were used to analyze the data. For quantitative data two-way ANOVA and Tukey post-hoc test were run. For qualitative data Pearson chi-square test was performed. Significance was set at 5%.

Results

44.5% of the horses showed one or more imaging finding. When the diameter of the joint was compared between imaging modality no statistical difference was observed. No differences were observed between left and right side or between gender. Nonetheless, statistically significant differences were observed when imaging findings were analyzed by discipline being polo horses the most affected.

Discussion/Conclusions

An important number of horses have imaging alterations in the TMJ. Radiographs and ultrasonography are readily available, and both can be used to get a proper assessment of the TMJ. The Polo, is a highly demanding discipline that demands sudden accelerations, turns and stops at high-speed forcing the raiders to be rough with the reins and bits probably predisposing to TMJ changes.

References

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