Pathologist Review Criteria

Complete Blood Counts (CBCs)

As a leader in pet-health diagnostics, IDEXX continually strives to provide the most complete information available to allow for the most effective case management possible.

The following is an overview of IDEXX Reference Laboratories Canada hematology test offerings, a summary of our pathologists' review criteria of the comprehensive CBC and a review of our laboratory processes.


CBC, Comprehensive

The comprehensive CBC (test code CCBC) provides a complete blood cell count, including reticulocytes, as well as a microscopic review of the blood smear by one of our laboratory technologists in order to:

  • evaluate cell morphology (RBC, WBC and platelets),
  • confirm automated cell count results,
  • provide a platelet assessment, and
  • identify abnormal cells and/or hemoparasites.

A pathologist review is automatically performed at no additional charge on samples that meet pre-established guidelines, when unclassified cells are identified, or if the technologist feels there is an abnormality that needs to be confirmed.

The preliminary report will indicate when a sample has been escalated for a pathologist review. The final report will provide a complete pathologist interpretation.

A detailed summary of our Pathologist Review Criteria that follows may also be found under the Protocol information for the comprehensive CBC in the Online Test Directory at, and can also be requested by contacting our Laboratory Customer Support Team at 1-800-667-3411, option 1, option 1.

Where possible, reference intervals are reported for most hematologic parameters. Reference intervals for the dog and cat were recently updated. Following the guidelines of the Clinical and Laboratory Standards Institute (CSLI) and the American Society for Veterinary Clinical Pathology (ASVCP), the new reference intervals were established using a clinically healthy population of dogs and cats and nonparametric statistical analyses.

Commitment to Quality

All hematology assays are performed in accordance with the testing practices of the Canadian Veterinary Medical Association using only fully trained and well-qualified lab personnel. Laboratory processes, report review and result interpretation is overseen by the Canadian Medical Review Board, made up of a team of board-certified veterinary pathologists and other veterinary professionals.

Pathologist’s Comment

A pathologist review of a comprehensive CBC (or equine CBC, avian/reptile CBC, LaserCyte/ProCyte Slide Review or urinalysis) may be requested either in advance of testing or when the pathologist review criteria are not met, by ordering the Pathologist’s Comment (test code PCOMM). For this test code, a pathologist review will be performed regardless of whether the sample meets the pathologist review criteria. A charge for the service will be applied.

As stated above, for comprehensive CBCs, a pathologist review is included in the CBC at no additional charge only when results meet the established review criteria.

CBC without Differential

The CBC without Differential (test code MCBC) is a partial CBC that reports machine parameters only. A slide evaluation is not provided. This test does not:

  • assess platelet clumping,
  • classify immature cell lines,
  • identify morphologic changes to platelets, red or white blood cells, nor
  • identify any blood parasites.

This test may be used for preanesthetic or routine preventive screening on healthy animals.

For a comprehensive CBC, including slide evaluation and pathologist review (if the sample meets the requirements of the Pathologist Review Criteria), the Differential and Smear Evaluation Add-on (test code DIFFA) may be requested within 24 hours of sample submission.

Review Criteria - Hematology

If one or more of the following criteria are met following a complete blood count and initial slide review, the sample is forwarded to the pathologist for review:

  1. Any immature lymphocytic cells or blasts
  2. Absolute lymphocyte count >11.0 x 10E9/L in Feline over 1 year
  3. Absolute lymphocyte count >6.0 x 10E9/L in Canine over 1 year
  4. Nucleated erythrocytes (NRBCs) >50 per 100 WBCs
  5. NRBCs less mature than metarubricyte
  6. Presence of NRBCs without polychromasia if >20 per 100 WBCs
  7. Presence of NRBC in the Equine
  8. Feline samples with suspected presence of Hemotropic Mycoplasma organisms with two or more of the following:
    a) Hct < 0.18
    b) RBC count <3.00 x 10E12/L
    c) Polychromasia (regeneration)
  9. Presence of questionable blood parasite inclusions including: Distemper Virus, Anaplasma spp., Ehrlichia spp., Plasmodium, Hemoproteus, Leucocytozoon, Microfilaria and Hemotropic Mycoplasma spp. (see item 8 above), and Babesia spp.
  10. Feline WBC >50 X 10E9/L
  11. Canine WBC >50 X 10E9/L
  12. Equine WBC >25 X 10E9/L
  13. Presence of Pelger-Huet anomaly
  14. Any unclassified cells, including mast cells
  15. Presence of ANY Heinz bodies in the Canine. Heinz bodies are verified and enumerated using the New Methylene Blue (NMB) stain
  16. Presence of eccentrocytes. Eccentrocytes are verified and enumerated using the New Methylene Blue (NMB) stain
  17. Presence of spherocytes (Canine)
  18. Bacteria in the peripheral blood smear

Note: Any suspicious or unclear finding in the blood film, including questionable RBC, WBC or platelet inclusion identification when a second technologist and/or the senior technologist are not in agreement, may be referred to a pathologist.

Review Criteria - Urinalysis

If one or more of the following criteria are met following urinalysis, then a cytospin, sediment smear or wet mount is prepared as appropriate and the sample(s) forwarded to the pathologist for review:

  1. Epithelial cells in sheets, and/or abnormal cells identified [Note: if urine is collected by catheter, then the presence of epithelial cells in sheets is normal.]
  2. Unidentifiable crystals
  3. Transitional epithelial cells observed in numbers of 10-20/HPF or greater
  4. Known history of bladder or prostate neoplasia.


Laboratory Customer Support

If you have any questions regarding test methodology, test codes, turnaround times or pricing, please contact our Laboratory Customer Support team at 1-800-667-3411, option 1, option 1.

Expert feedback when you need it

Our team of internal medicine specialists is available for complimentary consultation at 1-800-667-3411, option 1, option 3.