Changes in Heart Rate Variability with Induction of Gastric Ulcers in Adult Horses.

This study investigates how the induction of gastric ulcers impacts heart rate variability (HRV) in horses, providing insights that gastric ulceration, a condition often triggered by intense training, may decrease HRV and increase low-frequency fluctuations indicating increased sympathetic tone. It also concludes that omeprazole treatment helps in reducing heart rate and LF/HF ratio during ulcer induction.

Objective and Hypothesis of the Research

• The research aimed to explore how inducing gastric ulcers influenced heart rate variability (HRV) in adult horses. Researchers anticipated that the induction of these ulcers would lower HRV and heighten low frequency fluctuations – a situation synonymous with higher sympathetic tone.

Research Methodology

• A total of eight horses from a larger study were randomly selected as the sample. Half of these horses received a daily dose of 2 mg/kg omeprazole orally, while the other four received water only, for 28 days each.
• Gastric ulcers were induced on days 21 to 28 of the trial period using an intermittent feed withholding strategy. A gastroscopy was carried out, and the grade of gastric ulcers was evaluated (ranging from 0 to IV) by three impartial reviewers on days 21 and 28.
• One-hour continuous ECGs were recorded at the start and end of the ulcer induction period. HRV involved assessing time-domain variables in these one-hour recordings and frequency-domain variables in 5-minute sections.

Comparison and Analysis

• The researchers used a mixed effect model to compare HRV and ulcer grades across treatments. In this model, treatment and time acted as fixed effects, while the horse functioned as a random effect.
• The induction protocol significantly increased the ulcer grade (P < .0001). However, omeprazole intervention notably reduced it (P = .0007).
• The horses under the effect of omeprazole demonstrated increased R-R intervals (P = .01) and a decreased ratio of the low frequency to high frequency signals (P = .008) relative to the ones receiving water. This decrease was attributed to the reduction in low-frequency fluctuations (P = .05).

Conclusion Drawn from the Research

• Despite being limited by the small sample size, the research inferred that omeprazole treatment reduces heart rate and the LF/HF ratio during ulcer induction, implying a decrease in sympathetic tone.