Although salty water is not considered a drug by everyone, it is the single most useful way of treating sick animals.
The main function of the blood is to transport oxygen and nutrients to the tissues and take waste products away. To do this there must be adequate volume for the heart to pump, adequate lung function to get oxygen into the blood and adequate tissue blood flow to get oxygen to the cells.
Fluids can be lost directly by a variety of routes, or there can be a relative loss through vasodilatation (see shock). The differents routes of loss will result in other things apart from water being lost, for instance, excessive bleeding will cause loss of RBCs and clotting factors which will have to be replaced.
The body will adjust the fluid compartments (slowly) to try to maintain blood volume to preserve blood flow to the vital tissues (brain, heart and kidneys). Eventually homoeostasis breaks down and shock results.
| condition | loss | fluid used |
| haemorrhage | all blood components | mild - colloids (crystalloids) severe - (fresh) whole blood |
| dehydration (not drinking enough, evaporation) | water | NaCl 0.18% & dextrose 4%, dextrose 5% (KCl 10-20mmol/L added after 2d) |
| vomiting | water, H+Na+K+Cl- | NaCl 0.9% (KCl 10-20mmol/L added) Ringer's (KCl 10-20mmol/L added) |
| diarrhoea | water, HCO3-Na+K+Cl- | severe - Hartmann's extra KCl & NaHCO3 needed (unless Addisons or acute renal failure) mild - oral fluids |
| severe V & D | water, H+HCO3-Na+K+Cl- | colloid & Hartmann's |
| peritonitis | plasma & ECF | colloid & Hartmann's |
| gut obstruction | water, HCO3-Na+Cl- | colloid & Hartmann's & NaHCO3 |
| urethral obstruction / ruptured bladder | retention of H+ & K+ | NaCl 0.9% + dextrose 5% (& soluble insulin?) |
Water in the body
Fluid loss
Shock
Fluid therapy
Oral rehydration fluids
Intravenous fluids
Parenteral nutrition
Drugs for ketosis in ruminants
