Changes in heart rate, heart rate variability, and atrioventricular block during withholding of food in Thoroughbreds.
Abstract: To determine whether withholding of food affects autonomic nervous system balance by analysis of heart rate (HR), HR variability (HRV), and frequency of second-degree atrioventricular block in horses. Methods: 5 healthy Thoroughbreds. Methods: For two 24-hour periods in a crossover study, food was withheld from horses or horses were maintained on their regular feeding schedule (control conditions) in their stalls and Holter monitor ECG recordings were obtained. The ECGs were analyzed by use of fast-Fourier transformation, and power spectrum densities were calculated for low-frequency (0.01 to 0.07 Hz) and high-frequency (0.07 to 0.6 Hz) variations in HR. Serum cortisol and plasma ACTH, norepinephrine, and glucose concentrations were measured at predetermined time points. Results: Withholding of food resulted in significantly lower HR and more frequent second-degree atrioventricular block (the frequency of which was inversely related to the HR), compared with findings for control conditions. Circadian rhythms were similar during food-withholding and control conditions; peak HR was detected from 7:00 pm to 8:00 pm, and the lowest HR was detected in the early morning. During food-withholding conditions, the low-frequency and high-frequency components of HRV were significantly higher, and the low-frequency-to-high-frequency ratio was lower than during control conditions. Serum cortisol concentration was higher and plasma glucose concentration was lower at 6:00 pm in horses when food was withheld, compared with findings during control conditions. Conclusions: Indices of HRV seemed to be sensitive to changes in autonomic nervous activity and may be useful as clinical indices of the neuroendocrine response to stressors in horses.
Publication Date: 2012-03-29 PubMed ID: 22452497DOI: 10.2460/ajvr.73.4.508Google Scholar: Lookup
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- Journal Article
Summary
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The research article concerns a study on how withholding food from Thoroughbred horses impacts their autonomic nervous system balance, as indicated by changes in their heart rate, heart rate variability, and frequency of second-degree atrioventricular block.
Research Methods
- The research experiment was conducted on five healthy Thoroughbred horses.
- It involved two 24-hour periods where, in one cycle, horses were fed normally (control group), and in the other, food was withheld.
- During these periods, the horses were kept in their stalls and their heart functions were monitored using ECG recordings from a Holter monitor.
- The ECG readings were then analyzed using a technique called fast-Fourier transformation.
- The research also took into account the low-frequency and high-frequency variations in the horses’ heart rate.
- Blood samples were taken at predetermined times to measure cortisol, ACTH, norepinephrine, and glucose concentrations in the plasma.
Research Findings
- Findings showed that withholding food resulted in a notable decrease in heart rate (HR) and an increased frequency of second-degree atrioventricular block, a type of heart arrhythmia.
- The circadian rhythms of the heart rate remained similar whether food was withheld or not; peak HR was observed between 7:00 pm to 8:00 pm, while the lowest HR occurred in the early morning.
- The research also revealed significant increases in the low-frequency and high-frequency components of heart rate variability during periods when food was withheld.
- Additionally, the cortisol concentration in the horses’ blood was higher and the plasma glucose concentration lower at 6:00 pm during periods of food withholding.
Research Conclusions
- The researchers concluded that heart rate variability indicators can be responsive to changes in autonomic nervous activity. They suggest that these indicators could serve as clinical measures of the neuroendocrine response to stressors, like food deprivation, in horses.
Cite This Article
APA
Ohmura H, Boscan PL, Solano AM, Stanley SD, Jones JH.
(2012).
Changes in heart rate, heart rate variability, and atrioventricular block during withholding of food in Thoroughbreds.
Am J Vet Res, 73(4), 508-514.
https://doi.org/10.2460/ajvr.73.4.508 Publication
Researcher Affiliations
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA.
MeSH Terms
- Animal Husbandry
- Animals
- Atrioventricular Block / veterinary
- Autonomic Nervous System / physiology
- Cross-Over Studies
- Female
- Food Deprivation / physiology
- Heart Rate / physiology
- Horses / physiology
- Male
Citations
This article has been cited 5 times.- Ohmura H, Hiraga A. Effect of restraint inside the transport vehicle on heart rate and heart rate variability in Thoroughbred horses.. J Equine Sci 2022 Apr;33(1):13-17.
- Gehlen H, Faust MD, Grzeskowiak RM, Trachsel DS. Association Between Disease Severity, Heart Rate Variability (HRV) and Serum Cortisol Concentrations in Horses with Acute Abdominal Pain.. Animals (Basel) 2020 Sep 2;10(9).
- Zakari FO, Ayo JO, Rekwot PI, Kawu MU, Minka NS. Diurnal rhythms of heart and respiratory rates in donkeys of different age groups during the cold-dry and hot-dry seasons in a tropical savannah.. Physiol Rep 2018 Sep;6(17):e13855.
- Lenoir A, Trachsel DS, Younes M, Barrey E, Robert C. Agreement between Electrocardiogram and Heart Rate Meter Is Low for the Measurement of Heart Rate Variability during Exercise in Young Endurance Horses.. Front Vet Sci 2017;4:170.
- Ohmura H, Jones JH. Changes in heart rate and heart rate variability as a function of age in Thoroughbred horses.. J Equine Sci 2017;28(3):99-103.
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