Maintenance fluid therapy in horses

Maintenance fluid therapy is the provision of fluid and electrolytes necessary to maintain homeostasis of body water and electrolyte content on a daily basis. Maintenance fluids are generally considered to be hypotonic, unless free water needs are met through drinking; maintenance fluids often contain a higher concentration of potassium than do replacement fluids intended for the extracellular fluid (ECF) as potassium is the primary intracellular cation. Potassium may become deficient in horses off feed and receiving IV fluids without potassium supplementation. In addition to electrolytes, maintenance fluids may also contain dextrose; these dextrose-containing maintenance fluids may be isotonic in vitro, but effectively hypotonic as soon as dextrose is metabolized in vivo. A component of monitoring the adequacy of maintenance fluid therapy is evaluation for clinical signs of dehydration. Adverse effects of maintenance fluid therapy include fluid overload, catheter-related problems, and electrolyte disturbances.