Recombinant canine granulocyte colony-stimulating factor accelerates recovery from cyclophosphamide-induced neutropenia in dogs

In dogs injected intravenously with 400 mg/m2 cyclophosphamide (CPA), the peripheral neutrophil count decreased to less than 1000 cells/μL in 5–9 days. Treatment with purified recombinant canine granulocyte colony-stimulating factor (rcG-CSF), produced by brevibacillus expression system, at the nadir of the granulocyte count accelerated recovery from the CPA-induced neutropenia by 1–3 days. Therapeutic administration of rcG-CSF at doses of 2.5–10 μg/kg did not show any significant difference on the severity of neutropenia (the period that granulocyte counts were less than 2000 cells/μL). Administration of 2.5 μg/kg rcG-CSF 3 times per day 2–4 days or 3–5 days after CPA treatment not only accelerated recovery but also decreased the severity of neutropenia. No clinical signs of the rcG-CSF were observed. These results showed that the rcG-CSF is effective for treatment of neutropenia in dogs.