Evaluation of recombinant canine granulocyte-colony stimulating factor (rcG-CSF) in the treatment of Canine Parvovirus: preliminary results.

Introduction: The objectives of the study were: i) the evaluation of the clinical and hematological parameters of CPV2-naturally infected pups treated with the recombinant canine Granulocyte-Colony Stimulating Factor (rcG-CSF) in combination with the routine therapy, compared to similarly-managed infected pups not treated with rcG-CSF; ii) the assessment the patients recover and the survival rate. Methods: A non-randomized prospective clinical trial was conducted. Pups with gastrointestinal clinical signs (anorexia, vomiting and diarrhea) tested CPV2 positive with the commercial immunochromatographic test and with concurred leukopenia (WBC<4000/µL), were enrolled in the study. CPV2 positive samples were characterized by real-time PCR for the identification of the variant involved. Two groups of dogs were treated with conventional therapy with addition of daily 5µg/Kg of rcG-CSF (group A) or with conventional therapy alone (control group B). Blood samples were daily collected to monitor the haematological parameters. Results: Twenty-two leukopenic dogs with confirmed CPV2 infection were selected. Eight out of 22 dogs were included in group A and 14 in group B. CPV2a was identified in 4 and 8 dogs of group A and group B, respectively, CPV2b in 3 and 6 dogs, respectively, and only 1 CPV2c was identified in group A. At the end of the treatment mean (standard deviation) WBC were 21,32(8,38) K/µL and 4,92(4,37) K/µL respectively (p<0,0001), mean neutrophils count were 5,68(8,49) K/µL and 0,94(1,14) K/µL respectively (p<0,0192), mean monocytes count were 6,08(4,02) K/µL and 2,74(2,26) K/µL respectively (p<0,0175) and mean lymphocytes count were 9,44(7,7) K/µL and 2,07(2,57) K/µL respectively (p<0,0021). Time of hospitalization, survival rate and CPV2 variants had no significative differences due to low patients tested. Conclusion: In CPV2 infected dogs, the leukocyte count is significantly depressed and, since leukopenia greatly increases the probability of death, the effectiveness of rcG-CSF to manage parvovirus infection was evaluated. rcG-CSF improved hematological parameters compared to untreated dogs, but a larger sample is necessary for a better evaluation of the influence on the hospitalization time, on the survival rate and on the differences between the CPV variants.