Although rapid buffering by the blood and rapid dilution can allow a wider range of materials to be administered, injection into a peripheral vein can result in irritation, and in some circumstances flushing with normal saline should be considered.
It is common practice to stimulate dilation of the tail veins in rats either by placing them in a warmer environment (e.g. at 28-30 ºC) for up to 30 minutes, or by placing the tail in warm (30-35 ºC) water. If a warming box or incubator is used, its temperature should be monitored carefully. It is good practice to place an electronic thermometer adjacent to the animal’s cage in the incubator, as the temperature registered by the device thermostat may not be accurate.
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