Sleep pattern interference in dressage horses

Introduction

Horses adapted their polyphasic sleep pattern by dividing it into small fragments and alternating between REM phase (Rapid Eyes Movement) and NREM phase (Non-rapid Eyes Movement). REM sleep only occurs when the horse is in recumbency. Few studies present possible impairments when REM sleep is restricted.

Materials And Methods

In Brazil, ten Lusitano Pure Breed horses, age from 3 to 7, all Dressage athletes, were used in this randomized crossover experiment. REM sleep deprivation was accomplished by an observer not letting the horses enter in sternal or lateral recumbency for 72 hours. Horse grimace scale (HGS) was measured twice a day and heart rate variability (HRV) once a day and after the test competition. After 72 hours, horses participated in a test competition, with scores from three judges, two FEI certified and one veterinary doctor FEI certified. Riders and judges were blind to the experiment condition. This work was approved by the Ethics Committee on Animal Use (CEUA/FMVZ).

Results

Regarding HGS there were no alterations in score between control (not sleep deprived) and sleep deprivation groups. There was no difference between groups for seven HRV parameters evaluated. Three HRV parameters presented difference between 0h and after test competition for both groups. There is a significant statistical difference (p<0,05) between three judges.

Discussion/Conclusion

HGS can be a valuable tool to measure acute pain but cannot predict sleep deprivation on horses. Also, REM sleep deprivation does not cause pain facial expression. HRV did not appear to chance in regards of sleep deprivation in this specific population. Exercise changed HRV to a sympathetic regulation. Judge scores in dressage competitions seems to have weak to poor reliability and could not predict sleep deprived horses. 72 hours of REM sleep deprivation did not influence facial expression, HRV and performance in dressage horses.

References

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