title: Leukocyte count affects expression of reference genes in canine whole blood samples.
abstract: BACKGROUND
  The dog is frequently used as a model for hematologic human diseases. In this study the suitability of nine potential reference genes for quantitative RT-PCR studies in canine whole blood was investigated.
  
  
  RESULTS
  The expression of these genes was measured in whole blood samples of 263 individual dogs, representing 73 different breeds and a group of 40 mixed breed dogs, categorized into healthy dogs and dogs with internal and hematological diseases, and dogs that underwent a surgical procedure. GeNorm analysis revealed that a combination of 5 to 6 of the most stably expressed genes constituted a stable normalizing factor. Evaluation of the expression revealed different ranking of reference genes in Normfinder and GeNorm. The disease category and the white blood cell count significantly affected reference gene expression.
  
  
  CONCLUSIONS
  The discrepancy between the ranking of reference genes in this study by Normfinder and Genorm can be explained by differences between the experimental groups such as "disease category" and "WBC count". This stresses the importance of assessing the expression stability of potential reference genes for gene experiments in canine whole blood anew for each specific experimental condition.
authors.affiliation: Department of Clinical Sciences of Companion Animals, Utrecht, Utrecht University, PO Box 80154, 3508 TD Utrecht, The Netherlands. C.J.Piek@uu.nl.
authors.forename: Christine J
authors.initials: CJ
authors.lastname: Piek
authors.forename: Bas
authors.initials: B
authors.lastname: Brinkhof
authors.forename: Jan
authors.initials: J
authors.lastname: Rothuizen
authors.forename: Aldo
authors.initials: A
authors.lastname: Dekker
authors.forename: Louis C
authors.initials: LC
authors.lastname: Penning