The purpose of this study was to construct fundamental information for the usefulness and effects of thermography in Thoroughbred horses. total 10 horses were examined to determine a normal thermal pattern before and after sedation in lower limbs and ophthalmic area, and to investigate the effects of thermography during 42 days after induced wound and arthritis. In normal horses, the range of temperature difference(${Delta}T$) of symmetry site in lower limbs was 0.20 to $0.68^{circ}C$ on pre-sedation, which was simillar to that of post sedation, 0.17 to $0.74^{circ}C$, and eyeball area was 0.34 to $0.68^{circ}C$. Thermographically, the warmest area in normal limbs were coronary band of frontal view and the region between heel bulbs of back view. And temperature difference(${Delta}T$) after clipping in left forelimb was increased 1 to $3^{circ}C$ more than before clipping. However, there was no significant change of the temperature difference and degree of clinical signs by the process of inflammation healing during the experiment period in the all groups. These results suggest that the thermography was especially helpful in following clinical course of a disease because the thermal pattern will return to normal with declining clinical signs and healing of the lesion.