A new method for long-term intravenous alimentation in unrestrained rats

A new technique for continuous long term intravenous alimentation in unrestrained rats has been developed. The model involves the use of the intravenous tubing set which was constructed from the barrel of a 1 ml syringe-cylinder with flanges sutured to the rat's skin. After inserting the silicone catheter into the jugular vein the free end was exited at the intraauricular area and passed through the intravenous tubing set. The tubing was then connected with a silk suture to the top of the cage. This prohibits twisting of the system and allows unrestrained movement of the rat in the cage with a rotation of 6-8 turns in either direction. The metabolic cage was constructed from an inverted 4-liter glass jug with the base removed. A floor and root were fashioned from coarse wire screen. Urine and feces were easily separated and collected through the neck of the jug. This new "proxy" set was tested and compared with the standard swivel assembly parameters in rats infused by either method. However, the cost of the new set (excluding pump) was almost 90 times less than its commercially available counterpart. This self constructed approach should bring small animal research within the economic means of the most investigators.