Animal Health Diagnostic Center

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Clinical Pathology


Hematology Testing

We offer a variety of hematology group tests (e.g. hemogram) for both mammalian and non-mammalian species. Please refer to the detailed hematology group test list for additional testing information. Brief information on the more commonly used group tests are given below.

Group Tests

Routine hemogram (CBC):
This is performed in all mammalian species. Testing is performed with our hematology analyzer, the ADVIA 2120. The CBC provides white blood cell results (white blood cell count, differential cell count and leukocyte morphology), red cell results (red cell count, hemoglobin concentration, hematocrit, red cell indices and red cell morphology), platelet results (platelet count, mean platelet volume and smear estimate), total protein (by refractometer) and plasma appearance.

A reticulocyte count is automatically added to a CBC in anemic dogs and cats only. We also provide an absolute reticulocyte count, which gives a more accurate assessment of the bone marrow response to anemia than the reticulocyte percentage in these species.

Non-mammalian CBC:
These tests are run manually using bench methods. EDTA is the preferred sample for non-mammalian hemograms.

Also note that we do not have reference intervals for non-mammalian species.

Non-mammalian species represent a challenge to the clinician and clinical pathologist. Only small amounts of blood can be collected from most patients, necessitating the use of microtainer tubes. Similar to mammals, EDTA is the preferred anticoagulant for non-mammalian hematology. However, there are certain species of birds, e.g. cranes, and reptiles, e.g. turtles, whose blood hemolyzes on contact with EDTA. This hemolysis invalidates the PCV and affects assessment of red blood cell morphology during blood smear examination. For these species collection of blood into citrate or heparin may be needed. Please note that heparin will cause leukocyte and thrombocyte clumping which can invalidate WBC counts and differential cell counts.

Automated hemograms:
Our Advia hematology analyzer also provides an automated hemogram or an automated WBC panel. This is available for certain species only, including dogs, cats, horses, cattle, sheep, goats, pigs, mice, rats and certain species of monkeys. The only acceptable sample for a mammalian hemogram is EDTA (lavender top tube).

The automated hemogram (and WBC panel) is recommended for research samples and for pre-surgical screening in relatively healthy animals. These panels are not recommended for use in sick animals, because they do not include morphologic features, such as assessment of red and white cells, which can provide valuable information on underlying disease states.

Blood smear evaluation:
Included as part of the routine CBC and non-mammalian CBC. Can be requested separately if automated leukogram is abnormal or no EDTA sample is available (slides only).

 

Individual Tests

Many of our hematology tests can be ordered individually, rather than as group tests. This is useful for research samples. In this case, samples other than EDTA may be acceptable, however before samples are submitted to the laboratory for hematology testing in any other anticoagulant than EDTA, please contact the laboratory. Other individual tests performed in the laboratory are fibrinogen by heat precipitation and fecal occult blood. See below for more information.

Reticulocyte count:
Reticulocytes are automatically included as part of the routine (not automated) hemogram in anemic dogs and cats. A reticulocyte count will have to be specifically requested (and will be added at extra charge). We also provide absolute reticulocyte counts when a reticulocyte count is requested or added automatically to a hemogram. Please note, however, that an absolute reticulocyte count cannot be provided if a red cell count is not available for that sample (the absolute reticulocyte count is calculated from the product of the reticulocyte percentage and the red cell count).

Fibrinogen by Heat Precipitation:
This test is performed on EDTA samples only and is used for determination of fibrinogen concentration as an indicator of inflammation in large animals. Fibrinogen is an acute phase reactant protein and elevated values are seen in inflammation and renal disease (for the latter, in the cat and cow especially). This method of fibrinogen determination is not sensitive enough to detect decreased fibrinogen concentration in coagulation abnormalities.

Fecal occult blood:
The indication for this test is to help confirm suspected gastrointestinal blood loss. This test is performed on feces and is based on the pseudo-peroxidase activity of the heme component of hemoglobin using a guaiac paper test. In the test, heme (iron in the middle of a poryphyrin ring) oxidizes phenolic compounds in guaiac acid to quinones, producing a color change. The animal should be on a meat-free and peroxidase vegetable-free diet for up to 3 days prior to the test. This is because meat contains large amounts of hemoglobin and myoglobin, both of which contain heme, and plant peroxidases (e.g. from turnip, cauliflower, cantaloupe, parsnip, broccoli, horseradish, radish) will catalyze the reaction in the absence of heme, causing false positive reactions. To eliminate false positive reactions from plant peroxidases, any positive fecal occult test is confirmed by retesting 48 hours later. Plant peroxidase activity will decrease during this time, thus eliminating false positives. Note that with intermittent blood loss, a single fecal occult blood test may be negative. Testing on several different fecal samples is advised if gastrointestinal blood loss is strongly suspected.