## 2 Materials and Methods
### Thermal Imaging and Data Recording  
We assessed the local temperature of the metacarpal and coronary regions of the hoof in a healthy horse over 8 days, considering a fixed training protocol and limb cooling using an ice boot pack. The training protocol involved exercising the horse on a Haiko treadmill 5000 (Loimaa, Finland). Prior to the training period, the horse was habituated to the protocol over 5 days. Additionally, the same person handled the horse both on the treadmill and during the thermographic measurements. The treadmill exercise involved walking at 1.2 m/s for 5 min, followed by an increase in speed to 2 m/s for another 5 min, then trotting at 4 m/s [36, 37] for 20 min, and finally returning to walking at 1.25 m/s for 5 min (Video S1). After each training session, thermographic measurements of the thoracic limbs were taken. The same procedures were followed consistently throughout the 8-day study period. Thermographic measurements of the thoracic limbs were recorded to analyze temperature differences before and after training, as well as before and after applying a cooling method to the right thoracic limb. The thermographic measurements were taken before training (T1), immediately after training (T2), after applying the cooling method (T3), and at 10 min (T4), 20 min (T5), and 30 min (T6) post-application. The areas of interest for the right thoracic limb were Bx1 and Bx3, while for the left thoracic limb, they were Bx2 and Bx4 (Figure 1a,b). All thermographic measurements were performed indoors. To assess the effectiveness of the cooling method and the associated changes in temperature and thermal patterns, the right limb was designated as the study limb, to which an ice boot pack was applied at T3, while the contralateral limb served as the control. The ice boot pack was applied for 20 min and had a mean temperature of 3.8 \({}^{\circ}\)C (ranging from \(-\)0.4 \({}^{\circ}\)C to 7.5 \({}^{\circ}\)C) at the time of application (Figure 2a,b). Before the study began, the horse's hair was clipped, starting dorsally from the carpal joint region down to the hoof. Both during the habituation period preceding the study and throughout the study, the training sessions and thermographic measurements were conducted between 9 a.m. and 2 p.m. Each training day started with a one-hour habituation period in the treadmill room, during which indoor conditions were maintained with a temperature of 21-22 \({}^{\circ}\)C, humidity between 70 and 75%, and no air currents. The air temperature, humidity, and air currents were measured using the Testo 435 device (Testo, Titisee-Neustadt, Germany). The thermographic images were captured by the same non-blinded operator, who positioned themselves in front of the horse, holding the FLIR E50 thermography device (East Sussex, UK) 1 m away from the horse and at a 90\({}^{\circ}\) angle to the thoracic limbs (Figure 1a,b). On the thermal images, the color palette indicates the following: white represents the highest temperature, red represents a moderate temperature, yellow indicates a low temperature value, and blue represents the lowest temperature value. The thermographic images were captured using the FLIR E50 thermography device (FLIR Systems Inc., Wilsonville, OR, USA) with the following settings: 0.95 emissivity and a resolution of 240 \(\times\) 180 for each image. The temperature range was set from \(-\)20 \({}^{\circ}\)C to  
Figure 1: The forelimbs of the Warmblood mare: (**a**) normal image captured using the FLIR E50 camera; (**b**) thermographic image captured using the FLIR E50 camera. The red triangles indicate the maximum temperatures recorded in the areas of interest, while the blue triangles represent the lowest temperatures recorded in the same regions. 650 \({}^{\circ}\)C, with a sensitivity of \(\leq\)0.05 \({}^{\circ}\)C. A cardboard box was placed 20 cm from the thoracic limbs, under the abdomen, to minimize interference with the thermographic imaging of the pelvic limbs.