Hematology Sample Collection and Handling

Perform a venipuncture using the proper technique. Blood should be collected into a lavender top (EDTA) tube.

  • The specimen container must be at least half full.
  • Mix at least 10 times using gentle inversion immediately after collection. Avoid shaking the tube.
  • When collecting small volumes (e.g., small breeds, neonates), use an EDTA microtainer tube.
  • Make two air-dried blood smears as soon as possible following collection (particularly if the blood will not arrive at the laboratory the same day it is collected).
  • Keep slides at room temperature and protected in a rigid (e.g., plastic) slide holder.
  • Label tube and slides with the animal’s name, owner’s name, and collection date.
  • Keep whole blood refrigerated until shipping.
  • Ship whole blood with an ice pack. (Do Not Freeze)
  • Seal blood smears away from ice, protected from direct contact with the ice pack.
  • Do not allow smears to come in contact with formalin fumes.

Fresh smears are particularly important when evaluating blood smears for:

  • Morphologic evaluation of cells
  • Organism identification

High quality slides should have:

  • A feathered edge and extend 1/2 to 2/3 the length of the slide.
  • A thin monolayer region where erythrocytes and leukocytes can be adequately evaluated.
Quality Smear
Quality smear
Feathered Edge
Too long with feathered edge off stained area
Too Thick
Too thick with no feathered edge
Too Long Thick
Too long and thick
Abrupt Stop
Abrupt stop with no feathered edge
Too Short2
Too short

Blood smears submitted without whole blood are considered submissions for pathologist review and are processed as a cytology submission. If a CBC was performed on an in-clinic analyzer, please send results from the analyzer along with the blood smears to facilitate interpretation by the pathologist.

NOTE: 1) Submission of blood and slides for a CBC is less costly and provides more information than submission of only blood smears. 2) If blood submitted for a routine CBC is found to have unusual cells type or other sources of concern, the smear will be automatically sent to a clinical pathologist for further evaluation at no additional cost. 3) Pathologist review can be requested at no additional charge.

Hemostasis Sample Collection and Handling

Atraumatic venipuncture is crucial to minimize activation of coagulation factors and platelets. Collect blood into a light blue top (Na citrate) vacuum tube.

  • Fill light blue top (Na citrate) to fill mark on tube (this is critical for accurate results).
  • Do not over or under fill tube - this can falsely shorten or prolong clotting times.
  • Mix at least 10 times using gentle inversion immediately after collection.
  • Centrifuge specimen at 1,500 x g for 15 minutes as soon as possible and transfer plasma to a leakproof plastic tube.
  • For species other than dog, cat and horse, please submit a citrated plasma sample from a healthy patient of the same species to serve as a control.
  • Label tube with the animal’s name, owner’s name, and collection date. If a control is included, label with animal name and “control.”
  • Ship plasma overnight with an ice pack (dry ice is preferred). If the sample cannot be delivered to the laboratory within 24 hours of collection, the sample should be shipped frozen.

NOTE: If blood collection is difficult, collection from a different vein using a fresh needle is recommended. Collecting blood directly into vacuum tubes can be problematic, particularly in small dogs or cats because of collapsing veins. Blood can be collected using a needle and syringe (non-heparinized) then quickly transferred into a light blue top (Na citrate) tube.

Mammalian CBC

With the exception of llamas, camels, and deer, the mammalian CBC includes:

  • WBC concentration
  • WBC differential
  • RBC concentration
  • Hemoglobin (Hgb) concentration
  • Hematocrit (Hct)
  • Mean cell volume (MCV)
  • Mean corpuscular hemoglobin (MCH)
  • Mean cell hemoglobin concentration (MCHC)
  • Cell hemoglobin concentration mean (CHCM)
  • Red cell distribution width (RDW)
  • Platelet concentration
  • Mean platelet volume (MPV)
  • Plasma total protein (TP) concentration by refractometer
  • Spun Hct (packed cell volume, PCV)
  • Fibrinogen concentration determined by heat precipitation (equine and food animal only)
  • Cytograms and histograms from the automated hematology analyzer (ADVIA 2120) available upon request (see example below)
  • Microscopic examination of a blood smear

For llamas, camels, and deer, the CBC includes:

  • WBC concentration
  • WBC differential
  • Hemoglobin (Hgb) concentration
  • Mean cell hemoglobin concentration (MCHC)
  • Plasma total protein (TP) concentration by refractometer
  • Spun Hct (packed cell volume, PCV)
  • Microscopic examination of a blood smear
Additional Values Included on Mammalian CBC Reports Effective May 15, 2020
Advia Cytogram
ADVIA cytogram and histogram examples from a healthy dog
  • RBC VHC: (RBC Cytogram: X axis = hemoglobin concentration and Y axis = cell volume), A. macrocytic hypochromic erythrocytes, B. macrocytic normochromic erythrocytes or agglutinated erythrocytes, C. macrocytic hyperchromic erythrocytes, D. normocytic hypochromic erythrocytes, E. normocytic normochromic erythrocytes, F. normocytic hyperchromic erythrocytes, G. microcytic hypochromic erythrocytes, H. microcytic normochromic erythrocytes, I. microcytic hyperchromic erythrocytes.
  • PEROX: (WBC Cytogram: X axis = peroxidase staining and Y axis = cell volume) J. noise and platelets, K. lymphocytes, L. monocytes, M. neutrophils, N. eosinophils, O. LUCs (Large Unstained Cells that may be lymphocytes, monocytes, or blasts).
  • BASO: (WBC Cytogram depicting X axis = nuclear complexity and Y axis = platelet volume), P. basophils, Q. lymphocytes and monocytes, R. neutrophils and eosinophils.
  • PLT SCATTER: (Platelet Cytogram: X axis = refractive index and Y axis = platelet volume) S. platelets, T. large platelets, U. RBCs, V. RBC fragments, W. debris and ghost erythrocytes, X. ghost erythrocytes.

Non-mammalian CBC

Non-mammalian CBC is performed on blood from any animal with nucleated erythrocytes and thrombocytes (e.g., birds, reptiles, amphibians). These samples cannot be analyzed by the automated hematology analyzer. A non-mammalian CBC includes:

  • WBC concentration (calculated from microscopic cell count and WBC differential)
  • WBC differential
  • Plasma total protein (TP) concentration by refractometer
  • Spun Hct (packed cell volume, PCV)
  • Microscopic examination of a blood smear

NOTE: Some species of birds (particularly raptors) have lymphocytes that may lyse when they contact EDTA anticoagulant. Please prepare slides from fresh blood (not containing anticoagulant) immediately following collection for differential counting for these species.

Ensuring Accurate CBC Results

  • Clotted samples will be rejected because CBC findings would be inaccurate.
  • Underfilling EDTA tubes can alter erythrocyte parameters. Fill tubes to at least half the intended volume.
  • Lipemia may falsely increase Hgb concentration, plasma TP, MCH, and MCHC. These results may be reported, but a comment will be included stating that they may be erroneous.
  • Hemolysis may falsely increase MCH, MCHC and plasma TP. If hemolysis occurs in vitro, RBC concentration, Hct and spun Hct may be falsely decreased. These results may be reported, but it will be noted that they may be erroneous.
  • Erythrocyte agglutination interferes with RBC parameters. Automated results may not be reported if the results appear to be inaccurate based upon pathologist review of data and a blood smear.
  • Platelet clumping may falsely decrease platelet concentration and increase MPV. When clumping is detected on a blood smear, the automated platelet concentration will be reported, but should be considered a minimum value.
  • Ghost erythrocytes may falsely increase the automated platelet concentration. If ghost erythrocytes are detected and determined to be interfering with results, the platelet concentration will not be reported and the blood smear will be examined to estimate whether platelet concentration is adequate.
  • Cellular fragments from leukemic cells may falsely increase the automated platelet concentration.

Microscopic Review of Blood Smears

Blood smears are made from ALL samples and examined microscopically to:

  • Verify that data from the automated analyzer are correct.
  • Assess for morphologic changes or abnormal cells. See the table below for the grading scale used for reporting erythrocyte abnormalities.
  • Look for organisms or other non-cellular abnormalities.

NOTE: A microscopic WBC differential is provided if review of the blood smear appears to differ from the automated WBC differential. Smears with significant abnormalities are sent to a clinical pathologist for review. Blood smears are saved and a pathologist review can be requested at a later date.

Erythrocyte Abnormalities (average # of abnormal erythrocytes in 100× objective fields)

Polychromasia Grading Scales for Dogs, Cats, & Cows
  • mild



  • dog
    > 18
  • cat
    > 10
  • cow
    > 13
Grading Scale for All Species for Other Erythrocyte Changes
  • mild



  • hypochromasia, spherocytosis, microcytosis, macrocytosis, or unclassified poikilocytosis
    > 65
  • echinocytosis (do not report mild or moderate)
    > 100
  • codocytosis
    > 20
  • elliptocytosis
    > 10
  • keratocytosis
    > 10
  • acanthocytosis, dacryocytosis, drepanocytosis, eccentrocytosis, pyknocytosis, schizocytosis, or ghost cells
    > 10