Effect of different head and neck positions on behaviour, heart rate variability and cortisol levels in lunged Royal Dutch Sport horses.

The study evaluated the impact of different head and neck positions on the welfare of Royal Dutch Sport horses, monitoring behavior, heart rate variability, and cortisol levels during standardized exercise tests. The research identified specific positions that increased conflict behavior and stress responses in the horses.

About the Study

• In the effort to assess potential welfare issues in Royal Dutch Sport horses, researchers examined seven of these horses in predetermined head and neck positions (HNPs). These positions were classified as (1) Unrestrained position, HNP1; (2) Neck raised with nose around the vertical, HNP2; (3) Neck considerably lowered and flexed with nose pointing towards the chest, HNP4; (4) Neck raised and extended, nose in front of the vertical, HNP5; and (5) Neck lowered and flexed, nose pointing towards the carpus, HNP7.
• A standardised exercise test (SET) lasting 34 minutes, involving trotting, cantering and walking, was carried out while the horses were in these positions. Information about the horses’ behaviour, R-R intervals, and cortisol concentrations were documented at the start, 5 and 30 minutes after the SET.

Significant Findings

• Conflict behaviours, such as resistance or discomfort, increased significantly during HNP2 when compared with HNP1, HNP4, and HNP7 during exercise. Additionally, there was significant negative anticipation (potential anxiety or aversion) prior to assuming positions HNP2 and HNP7.
• HNP2 showed significant increases in the low frequency peak (LFpeak) of heart rate variability (HRV) compared to other positions, suggesting a shift to a more stress-responsive, sympathetic state. HNP2 also showed a decrease in very low frequency (VLF%) compared to HNP1.
• Further, HNP4 caused a significant increase in LF%, which indicates a sympathetic (stress-process) activation, and a respective decrease in VLF% when compared to HNP1.
• Cortisol concentrations in the saliva, commonly associated with stress levels, were significantly higher in HNP2 at both 5 and 30 minutes after exercise.

Conclusions

• The research pointed out that certain head and neck positions can induce stress and other welfare problems in Royal Dutch Sport horses. Particularly, HNP2 was identified as problematic, causing increased conflict behaviour, a heightened stress response as indicated by elevated cortisol levels, and a shift to sympathetic activation as displayed by altered HRV results.
• This research provides essential insights for horse trainers and riders to consider the impacts of these positions on horse welfare, especially during exercises.