Evaluation of thermal pattern distributions in racehorse saddles using infrared thermography

Abstract

The impact of a rider's and saddle's mass on saddle thermal pattern distribution was evaluated using infrared thermography (IRT). Eighteen racehorses were ridden by four riders with their own saddle. Images of the saddle panels were captured at each of six thermographic examinations. On each image, six regions of interest (ROIs) were marked on the saddle panels. The mean temperature for each ROI was extracted. To evaluate the influence of load on saddle fit, 4 indicators were used: ΔTmax (difference between the mean temperature of the warmest and coolest ROI); standard deviation of the mean temperature of the six ROIs; right/left; bridging/rocking and front/back thermal pattern indicator. Incorrect saddle fit was found in 25 measurements (23.1%) with ΔTmax greater than 2°C. The relationships between rider and saddle fit as well as saddle fit and horse were significant (p<0.001). An average ΔTmax in rider A was significantly higher than in other riders (p<0.001). The right/left thermal pattern differed significantly from the optimal value for riders A and B; while the bridging/rocking thermal pattern differed significantly from this value for riders A, C and D (p<0.05). Front saddle thermal pattern was most frequent for rider A (41.5%), whereas back saddle thermal pattern was most frequent for rider C (85.7%). Measurement of the mean temperature in 6 ROIs on saddle panels after training was helpful in assessing the influence of rider and saddle mass on saddle fit. IRT offered a non-invasive, rapid and simple method for assessing load on thermal pattern distribution in race saddles.

Fig 1. Thermographic image of saddle panels.

Thermographic image of saddle panels taken immediately after untacking the horse, with the six regions of interest (ROIs) indicated: right front of the saddle (X1), right middle of the saddle (X2), right back of the saddle (X3), left front of the saddle (X4), left middle of the saddle (X5), left back of the saddle (X6).

Fig 2. Receiver Operating Characteristic curve.

Receiver Operating Characteristic curve for ΔTmax with indicated cut-off score ΔTmax = 2°C, for which sensitivity (SE) is 54.6%, specificity (SP) is 88.0% and area under curve is AUC = 0.655.

Fig 3. Histogram of maximum temperature differences.

Histogram of maximum temperature differences ΔT_max at normal distribution and results of the normality test.

Fig 4. Number of training sessions in groups.

Number of training sessions in groups differing with rider and saddle fit and independence test results.

Fig 5. Number of training sessions in groups.

Number of training sessions in groups differing with horse and saddle fit and independence test results.

Fig 6. Comparison of the mean values of the temperature index.

Comparison of the mean values of the temperature index ΔTMAX of four saddles and the analysis of variance results (ANOVA) and multiple comparisons (post-hoc tests).

Fig 7. Comparison of the mean values of temperature indicators.

Comparison of the mean values of temperature indicators TI1 (right/left panel thermal pattern indicator) for four saddles and results of significance tests (T-tests for single means).

Fig 8. Comparison of mean values of temperature indicators TI2.

(bridging/rocking panel thermal pattern indicator) for four saddles and results of significance tests (T-tests for single means).

Fig 9. Number (fraction) of observations in subgroups.

Number (fraction) of observations in subgroups that differ in the temperature index TI3 (front/back panel thermal pattern indicator) and saddle and the result of chi-square independence test.