How do I interpret a canine CBC and chemistry panel and what abnormalities require immediate follow-up?

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A canine CBC and chemistry panel should be interpreted by comparing each value to species-specific reference intervals using absolute numbers, not percentages alone. The leukogram, erythron, and biochemical analytes each carry distinct diagnostic weight, and several abnormality patterns demand immediate follow-up action. 4 --- The leukogram is the most time-sensitive component of the CBC. A mature neutrophilia with monocytosis — without a left shift or toxic change — constitutes a classic stress or inflammatory leukogram. Examples from clinical cases include neutrophilia of 20.0 × 10³ cells/µL (reference interval RI 2.7–8.9 × 10³) with monocytosis of 1.8 × 10³ cells/µL (RI 0.1–0.8 × 10³) 1, neutrophilia of 19.3 × 10³ cells/µL (RI 2.7–9.4 × 10³) with monocytosis of 3.9 × 10³ cells/µL (RI 0.1–1.3 × 10³) 2, and neutrophilia of 15.99 × 10³ cells/µL (RI 2.95–11.64 × 10³) with monocytosis of 2.66 × 10³ cells/µL (RI 0.16–1.12 × 10³) 6. When a left shift is added — band neutrophils exceeding the upper reference limit — the pattern indicates active, demand-driven granulopoiesis consistent with significant infection or tissue necrosis; band neutrophils of 0.2 × 10³ cells/µL (RI 0.0–0.1 × 10³) 2 and 0.9568 × 10³ cells/µL (RI 0.0–0.3 × 10³) 3 have been documented in such cases. Toxic change in neutrophils — even mild (1+) — further elevates concern for sepsis or severe systemic inflammation and warrants immediate source investigation. 1 Thrombocytopenia below the reference interval requires urgent coagulation assessment. A platelet count of 104 × 10³/µL (RI 200–500 × 10³/µL) accompanied by a prolonged prothrombin time of 9.2 seconds (RI 5.5–7.9 seconds) and activated partial thromboplastin time of 20.0 seconds (RI 10.4–19.3 seconds) indicates concurrent coagulopathy and demands immediate evaluation for disseminated intravascular coagulation, immune-mediated thrombocytopenia, or a bleeding mass. 3 Conversely, thrombocytosis — such as 717 × 10³ thrombocytes/µL (RI 134–396 × 10³/µ