peer reviewed ; ("[en] BACKGROUND: Physiologic leukopenia in Tervuren dogs was reported in North America with a higher frequency in aged Tervurens. If not recognized, physiologic leukopenia can provoke unnecessary clinical investigations. HYPOTHESIS: The primary objective was to compare Tervurens and control dogs in Belgium with respect to the numbers of dogs with physiologic leukopenia. The secondary objectives were to compare Tervurens with control dogs and age classes within Tervurens and controls for parameters related to physiologic leukopenia. ANIMALS: Tervurens (n = 94) and control dogs (n = 48, maximum of 5 dogs per breed and 5 mixed breed dogs) were entered into the study. Dogs were 1-11 years old and healthy on routine physical examination. Dogs had no history of disease or drug administration in the previous 2 months. METHODS: Hematologic analyses were performed by an automated device within 30 hours of sampling. Blood smears were evaluated for cellular morphologic anomalies. RESULTS: Only 1 of the 94 Tervuren dogs had physiologic leukopenia (1.06%; 95% confidence interval, 0.05-5.22). Furthermore, the white blood cell (WBC) count in Tervuren dogs (median, 10.00 x 109/L; range, 5.90-20.80) was not significantly different (P = .55) from that of control dogs (median, 9.75 x 109/L; range, 5.20-20.90). The WBC count decreased significantly (P < .001) with age in Tervuren dogs. CONCLUSIONS AND CLINICAL IMPORTANCE: Physiologic leukopenia is uncommon in the Belgian Tervuren dog. Differences with earlier data published in North America might be due to genetic or environmental differences.