Abstract Objective—To determine reference ranges for results of hematologic analyses of healthy Belgian Tervuren, to compare results of hematologic analyses for healthy Belgian Tervuren with results for healthy dogs of other breeds, and to determine prevalence of physiologic leukopenia in Belgian Tervuren. Design—Cohort study. Animals—180 healthy Belgian Tervuren and 63 healthy dogs of other breeds. Procedure—Blood samples were analyzed by use of an automated device. Reference ranges were calculated for Belgian Tervuren by use of standard methods. Results—Total WBC counts of Belgian Tervuren ranged from 2.61 to 16.90 X 103/µl. Mean WBC count of Belgian Tervuren (mean ± SEM, 7.04 ± 0.16 X 103/µl) was significantly lower than mean count for control dogs. Significantly more Belgian Tervuren (65/180; 36%) than control dogs (2/63; 3%) had WBC counts < 6.00 X 103/µl. Percentage of Belgian Tervuren with WBC count < 6.00 X 103/µl was low for dogs ≤ 2 years old, increased sharply for dogs between 2 and 4 years old, and was approximately 65% for dogs > 4 years old. Neutrophil, lymphocyte, and monocyte counts were significantly lower, and RBC count, hematocrit, and eosinophil fraction were significantly higher in Belgian Tervuren than in control dogs. Conclusions and Clinical Relevance—Results suggest that physiologic leukopenia, resulting from low numbers of neutrophils, lymphocytes, and monocytes, may be a typical finding in a large percentage of healthy Belgian Tervuren and is not of clinical importance in otherwise healthy dogs. Healthy Belgian Tervuren may also have RBC counts and hematocrits higher than expected for healthy dogs.( J Am Vet Med Assoc 2000;216:866–871)