KRUUSE I Infusion Fluid Therapy in Rodents Fluid is typically administered via the subcutaneous route in rodents (3 ml/kg). Note that the subcutaneous route is not as effective for severely dehydrated animals because dehydration and hypothermia result in peripheral vasoconstriction and poor absorption. The goal of fluid therapy is to provide necessary fluid and electrolytes, meet metabolic demands, and restore intracellular water balance until the patient is eating and drinking on its own or recovered from surgery. The duration of treatment will vary from case to case depending on the patient’s health, treatment response, and/or recovery from a surgical procedure. The blood volume of a rabbit is 55-65 ml/kg in comparison with 90ml/kg in dogs, and high rates of infusion and excessive amounts of intravenous fluids may cause problems. Fluid therapy in rodents can be divided into two different causes: Correction of dehydration/deficits in clinically ill patients and maintenance. It is common to use colloids for the “correction stage” and crystalloids for maintenance. But practices usually have their tailored procedures, varying from case to case. Formula to determine volume of warmed fluid to be replaced: Body weight (grams) X % dehydration (as a decimal value) = Fluid volume (ml) Example: A 300 g rat who is estimated to be 5% dehydrated (skin tent of >2 seconds) 300 g X 0.05 = 15 ml of fluids needs to be replaced. Infusion rate? Replace 50% of the calculated volume immediately by the administration of a warmed fluid replacement solution (i.e., to body temperature, 37°C). Replace the remaining 50% after 2-3 hours. Re-evaluate the animal’s hydration status. www.kruuse.com
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