Short-term and long-term PQ, QT and R-R intervals’ variability at the resting condition and after exercise testing in healthy Anglo-Arabian horses.

This research examines how certain electrocardiographic (ECG) intervals (specifically PQ, QT, and R-R) vary in Anglo-Arabian horses during rest and after exercise. The study found that following exercise, these intervals were shorter than at rest, and that the variability of these intervals was generally higher during rest compared to after exercise.

Introduction and Objectives

• This research aimed to understand the duration and variability of certain electrocardiograph (ECG) parameters—PQ, QT, and R-R intervals—in Anglo-Arabian horses under resting conditions and after exercise testing.
• There was little prior data on how these parameters might be influenced by breed of the horse, hence this research targeted this gap.

Methods

• 27 healthy Anglo-Arabian horses (15 male, 12 female), averaging around 3.4 years, were examined using an ECG in a standing position, specifically with the Einthoven system of leads.
• The longest and shortest PQ, QT, and R-R intervals were measured both after night rest and after exercise testing. The average values of these intervals were then calculated for both conditions.

Results

• The disparities between the longest and shortest PQ, QT, and R-R intervals in resting and post-exercise conditions were quantified, revealing some distinct patterns.
• Post-exercise, all three intervals (PQ, QT, and R-R) were found to be shorter than in the resting state.
• The difference (delta) between PQ and R-R intervals after exercise was half of their resting state value, while the difference for the QT interval remained constant.

Conclusions

• Both at rest and after exercise, PQ and R-R intervals demonstrated a high degree of short-term variability, while QT interval variability was fairly stable.
• The variability of PQ and R-R intervals was seen to be higher at resting conditions compared to post-exercise. However, the variability in the QT interval was similar under both conditions.