Dosing & Blood Sampling

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Dosing

Efforts should constantly be made to refine scientific techniques so as to decrease the volume of blood samples required. In small animals such as mice, sample volume and frequency of sampling are of particular importance. If the animal's welfare may be compromised by the volume of the sample required, either more animals should be used or a compensatory volume replacement (such as warmed saline or a blood transfusion) should be performed. In general, the following points should be considered:

  • rather than multiple samplings carried out by repeated needle punctures, a butterfly needle or a percutaneous (over the needle) cannula taped in position should be used
  • in removing volumes greater than 0.1 ml, a needle with as large a bore as possible should be used, in order to ensure rapid blood withdrawal without collapsing the vein or causing formation of a hematoma
  • before taking a sample, it is important to accurately locate the vein and dilate it by gentle obstruction or warming (if general body warming is used, the animal must be constantly observed to prevent hyperthermia, as evidenced by more rapid breathing, panting or salivating)
  • the use of xylene (xylol, dimethylbenzene) as a dilator is not recommended as it causes skin rashes and is easily misused

Efforts should also constantly be made to refine techniques for animal dosing (including reducing volume size; improving solvent formulations and minimizing distress associated with dosing procedures).