EFFECTS OF PERIOPERATIVE GRANULOCYTE-COLONY-STIMULATING FACTOR ON HORSES WITH ASCENDING COLONIC ISCHEMIA

Granulocyte colony-stimulating factor (G-CSF) is a glycoprotein that r egulates the proliferation and maturation of hematopoietic progenitor cells and modulates the function of mature neutrophils. The responses to administration of G-CSF alone, and in combination with antimicrobia ls, were studied in an equine model of ascending colon ischemia. Compl ete segmental colonic ischemia (3.75 hours) with pelvic flexure entero tomy was created in four treatment groups. Group 1 horses received rec ombinant canine G-CSF (10 mug/kg, every 24 hours, intramuscularly), ge ntamicin sulfate (2.2 mg/kg, every 8 hours, intravenously), and potass ium penicillin G (40,000 IU/kg, every 6 hours, intravenously. Group 2 horses were treated with the G-CSF vehicle and antimicrobials as for g roup 1. Group 3 horses received G-CSF and the antimicrobial drug vehic les, and group 4 horses served as the untreated control receiving G-CS F vehicle and antimicrobial vehicles. The results for 20 horses, five horses in each group, were compared. Treatment with G-CSF was associat ed with an increased concentration of white blood cells, band neutroph ils, neutrophils, lymphocytes, and monocytes in the peripheral blood a fter surgery. Antimicrobial administration had no detectable effect on cell concentrations after surgery. Administration of G-CSF was associ ated with an increased concentration nucleated cells in the peritoneal fluid including neutrophils, small mononuclear cells and large mononu clear cells. Horses that developed incisional infections had lower neu trophil concentrations in the peripheral blood on postoperative day 2 than horses without infected incisions. These results suggested that t he prophylactic administration of G-CSF may be useful in the treatment of patients at risk for developing neutropenia after surgery.