Heart rate variability in horses with and without severe equine asthma.
Authors: Nyerges-Bohák Zsófia, Kovács Levente, Povázsai Ágnes, Hamar Enikő, Póti Péter, Ladányi Márta
Journal: Equine veterinary journal
Summary
# Heart Rate Variability as a Marker of Autonomic Dysfunction in Equine Asthma Severe equine asthma (sEA) affects 10–15% of the horse population, with pathophysiology remarkably similar to human asthma, yet non-invasive monitoring tools remain limited. Nyerges-Boháck and colleagues analysed heart rate variability (HRV) parameters in 20 horses with sEA and 20 asymptomatic controls, recording one hour of resting electrocardiographic data during mid-morning and examining multiple HRV indices using established time- and frequency-domain analysis. Horses with sEA demonstrated substantially reduced autonomic control across all measured parameters: SDNN fell from 82.7 to 41.3 ms, RMSSD from 86.0 to 55.3 ms, and total power from 4740.2 to 1503.0 ms², with similar magnitude reductions in parasympathetic (HF) and sympathetic (LF) markers (all p<0.01), suggesting that autonomic imbalance underpins the condition much as it does in human asthma. The SD2/SD1 ratio and total power emerged as the strongest discriminators between groups, indicating their potential utility in clinical assessment. These findings propose HRV measurement as a promising non-invasive approach for monitoring autonomic nervous system responses in asthmatic horses—particularly valuable for tracking disease progression and therapeutic response—though the small sample size warrants validation in larger populations before routine clinical implementation.
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Practical Takeaways
- •HRV analysis may offer a practical, non-invasive diagnostic aid to identify autonomic dysfunction in horses suspected of severe asthma, complementing clinical examination
- •The consistent reduction in HRV parameters in sEA horses suggests the condition has measurable effects on nervous system function that could be monitored during treatment response assessment
- •Further research is needed to establish HRV thresholds and validation protocols before implementing this tool routinely in clinical practice
Key Findings
- •Horses with severe equine asthma showed significantly lower heart rate variability parameters compared to asymptomatic horses across all measured indices (p<0.01 for each variable)
- •SD2, SDNN, TINN, SD2/SD1 ratio, and total power demonstrated the greatest discriminatory power between sEA and non-sEA groups
- •Asthmatic horses displayed reduced overall autonomic control with relative increase in parasympathetic modulation, mirroring findings in human asthmatic patients
- •Heart rate variability measurement via 1-hour ECG recording at rest could serve as a non-invasive monitoring tool for autonomic nervous system responses in sEA horses