title: Diagnostic accuracy of using erythrocyte indices and polychromasia to identify regenerative anemia in dogs.
abstract: OBJECTIVE
  To determine diagnostic accuracy of using erythrocyte indices and polychromasia to identify regenerative anemia in dogs.
  
  
  METHODS
  Retrospective and prospective cross-sectional study.
  
  
  METHODS
  4,521 anemic dogs.
  
  
  METHODS
  CBC results obtained between July 2002 and July 2008 by use of an automated laser-based flow cytometric hematology analyzer from dogs with Hct values ≤ 35% were retrieved. Sensitivity, specificity, accuracy, and predictive values of using erythrocyte indices and polychromasia to identify regeneration were determined, with a reticulocyte count > 65,000 reticulocytes/μL considered the gold standard. Similarly, 134 blood samples from anemic dogs were analyzed prospectively with an in-house electrical impedance analyzer.
  
  
  RESULTS
  Of 4,387 dogs with samples analyzed retrospectively, 1,426 (32.5%) had regenerative anemia. Of these, 168 (11.8%) had macrocytic hypochromic anemia. High mean cell volume and low mean cell hemoglobin concentration had low sensitivity (11%), high specificity (98%), and moderate accuracy (70%) when used to identify regenerative anemia. Use of polychromasia alone had an accuracy of 77%, and use of polychromasia combined with a high RBC distribution width (RDW) had an accuracy of 79%. Results obtained with the in-house analyzer were similar.
  
  
  CONCLUSIONS
  Results suggested that most regenerative anemias in dogs were not macrocytic hypochromic. Polychromasia, with or without high RDW, was a more accurate indicator than other erythrocyte indices of regenerative anemia. To avoid a false diagnosis of nonregenerative anemia, a blood smear should be evaluated in anemic dogs when a reticulocyte count is not available.
authors.affiliation: Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA.
authors.forename: Joanne
authors.initials: J
authors.lastname: Hodges
authors.forename: Mary M
authors.initials: MM
authors.lastname: Christopher
mesh_terms: D000740:Anemia / Q000097:blood / Q000175:diagnosis / Q000662:veterinary*; D000818:Animals; D001772:Blood Cell Count / Q000662:veterinary; D003430:Cross-Sectional Studies; D003937:Diagnosis, Differential; D004283:Dog Diseases / Q000097:blood* / Q000175:diagnosis*; D004285:Dogs; D004906:Erythrocyte Count / Q000662:veterinary; D004909:Erythrocyte Indices / Q000662:veterinary; D005260:Female; D006400:Hematocrit / Q000662:veterinary; D006402:Hematologic Diseases / Q000097:blood / Q000175:diagnosis / Q000662:veterinary; D008297:Male; D011446:Prospective Studies; D015203:Reproducibility of Results; D017701:Reticulocyte Count / Q000662:veterinary; D012189:Retrospective Studies; D012680:Sensitivity and Specificity