Evaluation of Recombinant Canine Granulocyte Colony‐Stimulating Factor as an Inducer of Granulopoiesis: A Pilot Study

Abstract

Five healthy young adult dogs were given recombinant canine granulocyte colony‐stimulating factor (rcG‐CSF) at a dosage of 5 μg/kg/day subcutaneously for 4 weeks to evaluate the effect on complete blood cell counts. The mean neutrophil counts ± standard deviation (SD) increased significantly (P < 0.01) from 6,537/μI ± 1,726 (range, 4,950–9,512/μl) to 26,330/μl ± 7,066 (range, 15,368–35,785/μl) within 24 hours after the first injection of rcG‐CSF. Mean monocyte counts ± SD were significantly increased (P < 0.05) from baseline values of 751/μl ± 168 (range, 444–891/μl) to 2,514/μl ± 878 (range, 1,740–3,752/μl) on day 5 of rcG‐CSF administration. Mean neutrophil and monocyte counts (±SD) continued to increase reaching a maximum of 72,125/μl ± 15,073 (range, 50,915–96,278/μl) and 3,972/μl ± 2,621 (range, 685–8,030/μl), respectively by day 19. These increased neutrophil and monocyte counts were maintained until the administration of rcG‐CSF was stopped. Blood counts returned to normal within 5 days after discontinuing the rcG‐CSF. One week after discontinuing treatment, rcG‐CSF was started again at 5 μg/kg/day subcutaneously. Within 48 hours following administration of rcG‐CSF, mean neutrophil counts ± SD increased from 5,860/μl ± 1,819 (range, 3,720–8,650/μl) to 57,444/μl ± 8,173 (range, 43,983–68,278/μl). Myeloid:erythroid ratios increased from a mean of 1.63:1 on day 1 prior to administration of rcG‐CSF to 3.3:1 on day 10 in three dogs for which bone marrow samples were evaluated. Recombinant canine G‐CSF did not cause clinically significant toxicosis in any of the dogs. Copyright © 1991, Wiley Blackwell. All rights reserved