Equis ISSN 2398-2977

Fluid therapy: overview

Contributor(s): Kate Baker, John R Dodam, Nicola Menzies-Gow

Introduction

Physiology

  • Total body water represents approximately 67% of the bodyweight of an adult horse.
  • Total body water is contained in the intracellular (ICF) spaces or the extracellular spaces (ECF).
  • ECF = plasma + interstitial fluid + water in the gastrointestinal tract (GIT) + lymph.
  • Hydrostatic forces and colloid osmotic pressure (COP) determine the distribution of water between the ICF and plasma.
  • Water balance in the horse is determined by intake (food and water) and by metabolism of body reserves versus excretion (urination, sweating, feces and respiration).
  • Normal maintenance requirements are 40-60 ml/kg/day which equates to 20 l/day for a 500 kg horse.
  • Sodium is the most abundant electrolyte in the ECF.
  • Sodium determines the ECF osmolarity and the volume.
  • Potassium is the most abundant cation in the ICF and has a central role in maintaining the electrochemical cell membrane gradient.

Golden rules

  • Establish what is lost.
  • Replace like with like (in terms of type of fluid lost and volume).
  • Continue fluid and electrolyte therapy to match on-going losses and satisfy maintenance requirements.

Goals of effective fluid therapy

  • Determine the deficit.
  • Decide which type of fluid to administer.
  • Calculate how much fluid to give.
  • Decide how to give the fluid, ie route and rate.

Methodology

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Which type of fluid?

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How much fluid to give?

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Methods of giving fluids

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What rate to give fluids?

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Hyppa S et al (1996) Restoration of water and electrolyte balance in horses after repeated exercise in hot and humid conditions. Equine Vet J Suppl 22, 108-112 PubMed.
  • Mealey R H et al (1995) Indwelling cecal catheters for fluid administration in ponies. J Vet Intern Med (5), 347-352 PubMed.
  • Seahorn T L et al (1994) Fluid therapy. Vet Clin North Am Equine Pract 10 (3), 517-525 PubMed.
  • Schott H C et al (1993) Fluids, electrolytes, and bicarbonate. Vet Clin North Am Equine Pract (3), 577-604 PubMed.
  • Roussel A J et al (1993) Urinary indices of horses after intravenous administration of crystalloid solutions. J Vet Intern Med (4), 241-246 PubMed.
  • Sneddon J C et al (1992) Effects of dehydration and rehydration on the intravascular space in horses. Comp Biochem Physiol Comp Physiol 103 (1), 163-167 PubMed.
  • Daunt D A (1990) Supportive therapy in the anesthetized horse. Vet Clin North Am Equine Pract (3), 557-574 PubMed.
  • Spier S J & Meagher D M (1989) Perioperative medical care for equine abdominal surgery. Vet Clin North Am Equine Pract (2), 429-443 PubMed.
  • Divers T J et al (1987) Acute renal failure in six horses resulting from hemodynamic causes. Equine Vet J 19 (3), 178-184 PubMed.
  • Rose R J et al (1986) An evaluation of an oral glucose-glycine-electrolyte solution for the treatment of experimentally induced dehydration in the horse. Vet Rec 119 (21), 522-525 PubMed.
  • Denkhaus M et al (1986) Adverse effects following intravenous fluid therapy in the horse using non-commercial fluids - preliminary findings. J S Afr Vet Assoc 57 (2), 105-107 PubMed.
  • Brown M D (1982) Simplified large animal fluid therapy. Mod Vet Pract 63 (9), 703-706 PubMed.
  • Rose R J (1981) A physiologic approach to fluid and electrolyte therapy in the horse. Equine Vet J 13 (1), 7-14 WileyOnline.
  • Mason T A (1972) A practical approach to fluid therapy in the horse. Aust Vet J 48 (12), 671-676 PubMed.


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