Blood and Urine Sampling

Abstract

Every clinical pathology measurement can be undermined by poor sample collection, and there are many ways that samples can be compromised. A long list of tests can be ruined by red blood cell hemolysis and the presence of bilirubin because of improper blood collection technique. Similarly, a failure to properly fast animals can cause serum to be lipemic, which can interfere with many tests. Blood should be drawn from the same site, and at the same time of day throughout serial samplings. This is essential in rodents since their leukocyte counts fluctuate widely due to circadian effects and sampling site. Cell counts in all species differ depending on the collection site. When an animal is stressed during blood collection, there is a release of corticosteroids, splenic contraction, and the release of additional cells into circulation; and blood chemistries are also affected. Four methods for collecting urine are described along with their strengths and weaknesses. There is no ideal way to preserve urine so the means used are dictated by the evaluations needed.