Which IV fluid when?

Replacement fluids rapidly distribute to the compartments of the extracellular fluid (ECF). They are isotonic and should be used to replace deficits in hypovolaemic and dehydrated animals. Maintenance fluids provide free water that distributes to both the intracellular fluid (ICF) and ECF. They should be used to maintain fluid balance following rehydration in horses that need ongoing i.v. support. As continued use of replacement fluids may cause hypernatraemia and hypokalaemia, maintenance fluids contain a lower sodium concentration and a higher potassium concentration, being made isotonic with dextrose. Increased levels of calcium and magnesium are also present. However, an appropriate fluid can be made by adding 5% dextrose and potassium to either isotonic saline or one of the replacement type fluids ...