Equine plasma and blood volumes decrease with dehydration but subsequently increase with exercise.
Abstract: The effects of dehydration and 40 min of exercise at approximately 40% of maximal O2 consumption on plasma volume (PV) and blood volume (BV) were studied in six horses. Horses were exercised while euhydrated (C); 4 h after administration of furosemide (1.0 mg/kg i.v.; FDH), which induced isotonic dehydration; and after 30 h without water (DDH), which caused hypertonic dehydration. Dehydration resulted in decreases of 6.3 and 9.9% for PV and BV, respectively, with FDH and 10.7 and 8.5%, respectively, with DDH. During exercise in C, PV and BV increased by 12.7 and 20.0%, respectively; during exercise with FDH, they increased by 11.7 and 26.1%, respectively; and during exercise with DDH, PV decreased by 1.3% from predehydration values, while BV increased by 18.7%. Hematocrit and total plasma protein concentration rose to higher values throughout exercise in FDH and DDH than in C; plasma [Na+] was higher in DDH than in FDH and C, [Cl-] was higher in DDH and lower in FDH than in C, and [K+] was lower in FDH and DDH than in C through exercise and recovery. From these results, we conclude that increases in PV and BV are normal features of low-intensity exercise in the horse. The increases in BV not only augment O2 carriage but also help maintain circulating volume. These increases can be modified by preexercise dehydration, the nature of which affects the extent of modification.
Publication Date: 1993-08-01 PubMed ID: 8226442DOI: 10.1152/jappl.1993.75.2.1002Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research investigates how dehydration and exercise affect the overall plasma volume and blood volume in horses. It shows that these volumes decrease with dehydration but rise with low-intensity exercise.
Study Design and Experiment
- The research involved six horses and studied the effects of dehydration and 40-minutes of exercise at approximately 40% of the horse’s maximal oxygen consumption.
- The tests were conducted when the horses were fully hydrated (C), 4 hours after they had received an intravenous dosage of furosemide (FDH) (a diuretic inducing isotonic dehydration), and 30 hours of water deprivation (DDH), resulting in hypertonic dehydration.
Findings from the Study
- According to the study, dehydration resulted in a reduction of plasma volume (PV) and blood volume (BV). Specifically, a decrease of 6.3% for PV and 9.9% for BV was observed with FDH administration, while in a state of DDH, the respective decreases were 10.7% and 8.5%.
- During exercise when the horses were fully hydrated, there was an increase of 12.7% for PV and 20% for BV. However, during exercise after administering FDH, these rates increased by 11.7% and 26.1% respectively. In the case of exercise after DDH, PV showed a decrease of 1.3% from pre-dehydration values, while BV increased by 18.7%.
- Exercise under dehydration (FDH and DDH) resulted in higher hematocrit levels and total plasma protein concentration compared to the baseline condition, indicating concentration of blood due to loss of water. On the other hand, sodium concentration was higher during DDH, contrasting with FDH and the control. Chloride ions concentration was higher during DDH, and lower during FDH compared to the control. Potassium concentration was lower throughout both the FDH and DDH phases of the exercise and recovery.
Conclusion from the Study
- This study revealed that increased blood volume and plasma volume are normal biological responses to low-intensity exercise in horses. These increases support oxygen carriage and maintain the circulating volume in the horse’s body.
- However, these increases can be affected by dehydration before exercise with the extent of the modification largely influenced by the severity of the dehydration.
Cite This Article
APA
Naylor JR, Bayly WM, Schott HC, Gollnick PD, Hodgson DR.
(1993).
Equine plasma and blood volumes decrease with dehydration but subsequently increase with exercise.
J Appl Physiol (1985), 75(2), 1002-1008.
https://doi.org/10.1152/jappl.1993.75.2.1002 Publication
Researcher Affiliations
- Department of Veterinary Clinical Medicine and Surgery, College of Veterinary Medicine, Washington State University, Pullman 99164.
MeSH Terms
- Animals
- Blood Proteins / metabolism
- Blood Volume / physiology
- Dehydration / chemically induced
- Dehydration / physiopathology
- Electrolytes / blood
- Female
- Furosemide / pharmacology
- Hematocrit
- Horses / physiology
- Male
- Physical Exertion / physiology
- Plasma Volume / physiology
- Water Deprivation / physiology
Citations
This article has been cited 6 times.- Lisboa BRF, da Silva JAR, da Silva WC, Barbosa AVC, Silva LKX, Lourenço-Júnior JB. Evaluation of thermoregulation of horses (Equus caballus) submitted to two methods of post-exercise cooling, in hot and humid climate conditions, in the Eastern Amazon. Front Vet Sci 2023;10:1150763.
- Cannes do Nascimento N, Dos Santos AP, Sivasankar MP, Cox A. Unraveling the molecular pathobiology of vocal fold systemic dehydration using an in vivo rabbit model. PLoS One 2020;15(7):e0236348.
- Oleson S, Cox A, Liu Z, Sivasankar MP, Lu KH. In Vivo Magnetic Resonance Imaging of the Rat Vocal Folds After Systemic Dehydration and Rehydration. J Speech Lang Hear Res 2020 Jan 22;63(1):135-142.
- Grimsrud KN, Ait-Oudhia S, Durbin-Johnson BP, Rocke DM, Mama KR, Rezende ML, Stanley SD, Jusko WJ. Pharmacokinetic and pharmacodynamic analysis comparing diverse effects of detomidine, medetomidine, and dexmedetomidine in the horse: a population analysis. J Vet Pharmacol Ther 2015 Feb;38(1):24-34.
- Muir WW, Yiew XT, Bateman SW, Hahn RG. Volume kinetics of lactated Ringer's solution in adult horses. Equine Vet J 2026 Jan;58(1):220-229.
- Bayly WM, Leguillette R, Sides RH, Massie S, Guigand C, Jones KB, Warlick LM, Thueson EL, Troudt TA, Slocombe RF, Jones JH. Equine exercise-induced pulmonary hemorrhage: the role of high left-heart pressures secondary to exercise-induced hypervolemia, and high inspiratory pressures. J Appl Physiol (1985) 2024 Nov 1;137(5):1359-1373.
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