Haematological, bone marrow and clinical chemical changes in neonatal foals given canine recombinant granulocyte-colony stimulating factor.

Five Thoroughbred and Quarter Horse cross foals were given 20 micrograms canine recombinant granulocyte-colony stimulating factor (rcG-CSF) per kg bwt intramuscularly (i.m.) on the day of birth and 10 micrograms rcG-CSF/kg for 13 additional days. During this time and for an additional 21 days haematology, bone marrow and clinical chemical analyses were performed. After one day of rcG-CSF administration leucocyte and neutrophil counts increased from 9.16 x 10(9)/l to 23.44 x 10(9)/l and from 6.45 x 10(9)/l to 19.61 x 10(9)/l, respectively. The counts continued to increase for the next 3-4 days and then there was a slight decrease. A second increase followed and the leucocyte and neutrophil counts increased to 52.84 x 10(9)/l and 45.16 x 10(9)/l on the day after the last rcG-CSF administration (Day 15). The counts decreased rapidly immediately after the administration of rcG-CSF was stopped and then at a slower rate. The cell counts were still higher than in the controls at the end of the study period (Day 35). Bone marrow cellularity increased from 10-25% before rcG-CSF was given to 60-80% after 5 days. The increase in cellularity was due to increased myeloid activity because the myeloid to erythroid ratio increased from 2.7 to 8.8. Serum chemistry changes were minimal although foals given rcG-CSF at various times had lower glucose concentrations and increased alkaline phosphatase and gamma glutamyl transferase activities.