The shock dose is an estimate of the total blood volume (dogs, 90 mL/kg/hr; cats, 60 mL/kg/hr). It is unlikely that a hypovolemic patient will have lost its entire blood volume; thus, approximately 25% of the fluid prescription (dogs, 20 mL/kg/15 min; cats, 15 mL/kg/15 min13) should be administered using pressure bags, fluid pumps, or a 60-mL syringe. Fluid pumps run at 999 mL/hr and are best used for boluses when the total volume to be infused over 15 minutes is less than 250 mL.
The patient should be re-evaluated after the fluid bolus is given. Additional fluid boluses can be administered (dogs, ≤90 mL/kg/hr; cats, 60 mL/kg/hr) if clinical parameters of hypovolemia have improved but are not yet satisfactory (see Oxygen Delivery Restoration Parameters). Fluid administration can be discontinued when the patient has met the desired criteria, but, because isotonic crystalloids have a short lifespan in the intravascular space, the patient’s vital parameters should be monitored closely.
Synthetic colloids (eg, hydroxyethyl starch solutions; 1-5 mL/kg every 15 minutes) can be used to treat hypovolemia. The author prefers to use the low end of the dose range for cats, whereas dogs tend to tolerate the higher end.