School of Veterinary Medicine

Comparative Pathology Lab

About Clinical Pathology, Automated and Manual Analysis

These services primarily include clinical chemistry and hematology analysis.  In addition to routine chemistry screening panels, CPL specializes in performing assays optimized for the micro-sample volumes commonly encountered in rodent biology.  Our extremely experienced staff members have the training and mindset to maximize the amount of data we can generate with your limited specimens.  We have selected our instrumentation to decrease dead-space assay volumes, so that we maximize the number of tests results obtained per sample.  Our computerized analyzer is capable of performing a wide variety of tests, and we specially choose certain methods that are advantageous to rodent researchers.  Be sure to inquire about special kidney, liver and cardiac function panels, as well as carbohydrate and lipid metabolism assays, which we specialize in.

  • Quantitative urine chemistries such as urine micro-albumin, urine total protein, glucose, creatinine, urea nitrogen, calcium, magnesium, phosphorus, sodium, potassium may also be requested.
  • We also offer clinical urinalysis, which includes microscopic examination of urine sediment and urine dipstick chemistries to semi-quantitatively detect glucose, bilirubin, ketones, urobilinogen, occult blood, protein, pH and specific gravity in either random collections from cystocentesis or pooled collections from metabolic cage systems.
  • Our hematology analyzer has likewise been chosen to accommodate micro-samples.  The special veterinary software is optimized for mice, rat, feline, canine, lagomorph, ovine or porcine species.  Typically, hematological blood counts, including 5-part differential white blood cell counts and red cell indices, require approximately 30 uL!  We recommend that researchers collect 50-100 uL however, for better physical mixing and analyzer sampling.  The most common hematological analysis performed is the CBC (Complete Blood Count).  These are the following components of that profile:
    • WBC (total white blood cell count)
    • Segmented neutrophils (expressed as an absolute number of cells or a percentage of the total number of WBCs)
    • Lymphocytes (expressed as an absolute number of cells or a percentage of the total number of WBCs)
    • Monocytes  (expressed as an absolute number of cells or a percentage of the total number of WBCs)
    • Eosinophils  (expressed as an absolute number of cells or a percentage of the total number of WBCs)
    • Basophils  (expressed as an absolute number of cells or a percentage of the total number of WBCs)
    • RBC (total red blood cell count, Red cell Distribution Width may be requested as an option)
    • Hemoglobin concentration
    • Hematocrit
    • MCV (Mean Corpuscular red cell Volume)
    • MCH (Mean Corpuscular Hemoglobin)
    • MCHC (Mean Corpuscular Hemoglobin Concentration)
    • Platelet count (Mean Platelet Volume may be requested as an option)
  • If a manual review of the blood is desired, a peripheral smear can be prepared by special request.  We use a Wright Giemsa stain for these smears and manual WBC differential counts may be performed on these preparations.
  • Manual reticulocyte counts may also be performed by request.  We prepare the whole blood specimen with a New Methylene Blue supravital stain.

Specimen Collection, Preservation and Transport

Whenever possible, please ship or deliver early in the week to facilitate processing.  We recommend “overnight priority” shipping in insulated containers where possible.  UC Davis campus does not accept deliveries on UC holidays or weekends.  This facility’s security gates will be locked unless special arrangements are made.  Thank you for understanding!

Hematology specimens:

EDTA or lithium heparin whole blood is used for hematology analysis.  For accurate cell counts, it is essential that the specimens be clot-free.  For this reason, immediate and thorough mixing of whole blood must occur to distribute the anticoagulant uniformly.  Although complete mixing is crucial, so is gentle treatment of the specimen, as cells are fragile.  Excessive mechanical trauma from forceful syringe aspiration or rapid dispense through a small bore metal needle can create lysis of cells.  Cells are also susceptible to freezing damage.  Direct contact of blood tubes with ice packs or dry ice can also create severe lysis, which will adversely affect analysis. CBC specimens may be sent with either ice or with frozen ice packs, as long as some kind of insulating paper or gauze is used to separate tubes from direct contact.  Ideal temperature range for preservation of whole blood is 2-8°C.  Submission to CPL should be during the date of draw and about 48 hours is the longest we recommend to delay before analysis.  We recommend the BD (Becton-Dickenson) brand of microtainer with powdered anticoagulant inside:  lavender-topped EDTA or green-topped lithium heparin tubes.  These present less dilution of the original specimen and yield more accurate results. 

Chemistry specimens:

Serum, lithium heparin plasma, EDTA plasma and urine are commonly submitted specimen types.  In most cases, routine clinical chemistries are most often performed on cleanly separated serum.  That is, the clear yellowish fluid that can be collected once a whole blood specimen (drawn without the addition of anticoagulants in the tube) has clotted undisturbed for 30-60 minutes, and then centrifuged to at least 3000 rpm for 6-10 minutes.  Since rodent blood clots very quickly, some researchers find it easier to sparingly coat the insides of their aspiration syringe with dilute liquid lithium heparin anticoagulant.  This is fine for most chemistries, because lithium heparin plasma is generally interchangeable with serum.   The major exception to this is the assay for Non-Esterified Fatty Acid (NEFA), which utilizes serum or EDTA plasma.  Plasma derived from EDTA anticoagulant may sometimes be used for chemistries, but there are some significant exceptions!  Calcium, Alkaline Phosphatase, Sodium, Potassium, Magnesium, Iron, Total CK are all severely affected by the presence of EDTA.  Repeated freeze-thaw cycles should be avoided in the storage and transport of chemistry specimens.  Generally, if analysis is going to occur within 24 hours, a cleanly separated serum or plasma sample can be preserved safely at 2-8°C, and shipped using standard ice packs.  For storage longer than 48 hours, freezing specimens should be considered.  Please observe postal regulations regarding dry ice shipments.

We recommend the use of BD (Becton-Dickenson) brand of blood collection microtainers. These are available from scientific vendors without additives; or with inert serum separator gel; or with lithium heparin; or EDTA anticoagulants. 

For your convenience, here are the VWR Scientific catalog numbers for blood collection microtainers, which come in packs of 50 units or cases of 200 units:

Gold-topped tubes for serum collections only, containing inert serum separator gel, can hold up to 600 uL sample volume.  Catalog#  VT365956

Red-topped tubes with no additive, for serum collections, can contain up to 700 uL.  Catalog#  VT365957

Green-topped tubes with lithium heparin anticoagulant for whole blood or plasma collections.  Enough anticoagulant to treat 400 uL of whole blood.  Catalog#  VT365971

Mint green-topped tubes containing lithium heparin anticoagulant and inert plasma separator gel for plasma collections only.  400 uL capacity.  Catalog#  VT365958

Lavender-topped tubes containing potassium EDTA anticoagulant, for whole blood and plasma collections.  Enough anticoagulant to treat 500 uL of whole blood.  Catalog#  VT365973