Water treadmill training causes a significant increase in back dimensions at the level of Th10 in warmblood riding horses without a history of back pain

Background
Back pain is common in ridden horses. Data on the effect of water treadmill training (WT) as a potential preventive strategy in horses is sparse.
Objectives
The aim of this study was to identify the effects of 9 weeks WT on back dimensions in warmblood riding horses without back pain.
Materials and Methods
Fifteen horses (median age 9 years) were trained three times per week up to 30 minutes on a water treadmill. The remaining days the horses were in ridden training. Back dimensions were objectively assessed at week 0, 3, 6 and 9. A flexible curved ruler was shaped three times along the transverse contour of the back at the level
of Th10, Th14, Th18 and L3. The contours were digitalized and areas under the curve (AUC) to a level 10 cm below the dorsal midline contour were calculated.
Results
The AUC increased over time at the level of Th10 (marginal means and 95% CI at week 0: 1649 [1488–1810] cm², week 3: 1688 [1532–1844] cm², week 6: 1727 [1571–1883] cm², week 9: 1766 [1605–1927] cm², adj. P = 0.034) but not at the caudal levels.
Discussion
The results indicate that WT may lead to an increase in muscle cross section caudal to the withers but not in the caudal thoracic and lumbar region.
Main limitations
Small sample size and lack of control group.
Conclusions
WT potentially contributes to muscle hypertrophy at the level of Th10 in warmblood riding horses without back pain.
Conflict of interest: The authors declare no conflict of interest
Ethical committee: The study was approved by the ethics committee of the responsible German federal state authority (State Agency of Nature, Environment and Consumer Protection North Rhine-Westphalia, AZ: 81-04.13)
Sources of funding: Liesa Rogge was temporarily funded by “Konrad-Adenauer-Foundation”