We examined the rat and noted a 5-mm-diameter round mass on the plantar surface of the left hind limb. The mass was firm and grayish-red in color and had visible blood vessels coursing across its surface (Fig. 1b). The rat was in good body condition and showed no evidence of trauma on its body; palpation of the mass did not appear to cause any pain. The mass did not impede walking or seem to trouble the rat. We found no other abnormalities during our clinical examination.
We took a blood sample for a complete blood count and small animal biochemistry analysis. Blood was collected using a 22-gauge needle with syringe via standard tail vein venipuncture technique and immediately placed into EDTA and serum tubes for hematology and serum chemistry analysis. Blood and serum were processed and analyzed within 2 h at the Colorado State University School of Veterinary Medicine Clinical Pathology laboratory. The samples were evaluated using an automated hematology analyzer (Bayer Advia 120, Bayer Inc., Pittsburgh, PA). Chemistry samples were evaluated using a Hitachi 917 automated analyzer (Roche Inc., Basel, Switzerland). Both instruments are validated to analyze clinical samples from Sprague-Dawley rats. Hematology and biochemistry results were within normal ranges1,2. Microscopic examination of blood smears showed rare lymphocytes with azurophilic granules, rare giant platelets, few acanthocytes, few keratocytes, moderate echinocytosis and slight polychromasia.
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