Dascalu, M.A.; Daraban Bocaneti, F.; Soreanu, O.; Tutu, P.; Cozma, A.; Morosan, S.; Tanase, O. Filgrastim Efficiency in Cats Naturally Infected with Feline Panleukopenia Virus. Animals 2024, 14, 3582. https://doi.org/10.3390/ani14243582
One of the most severe and highly infectious diseases in cats is feline panleukopenia (FPL), caused by Feline Panleukopenia Virus (FPV). It is characterized by low survival, with reports of mortality rate ranging from 25% to 90%. Filgrastim, a granulocyte colony-stimulating factor (G-CSF), is a human drug that has been tested but rarely used in veterinary therapy, including for felines with FPL. Filgrastim is commercially available as Neupogen ® (Amgen, Inc. USA ), or Zarzio ® (Sandoz, Austria), among others. The authors of this study describe the use of the latter in this article, the first to use Zarzio ® on cats to their best knowledge.
The retrospective study included 22 cats (8 female, 14 male) aged between 3 months and 5.7 years that were seen at the Infectious Diseases Clinic, within the Department of Public Health, Isai University of Life Sciences, Romania, between January 2022 and September 2024 with a diagnosis of FPL. Physical exam revealed most of the cats exhibited non-specific symptoms, including lethargy, depression, inappetence, and fever. During subsequent hospitalization, additional symptoms, including GI symptoms, developed.
To determine the presence of FPV infection, each cat was screened for FPV fecal antigen with either qualitative or quantitative immunochromatographic rapid tests. All 22 cats tested positive for FPV and panleukopenia was confirmed by complete blood count (CBC). CBC revealed the following blood conditions: leukopenia (22/22), lymphopenia (18/22), monocytopenia (20/22), neutropenia (20/22), eosinopenia (12/22) and basopenia (22/22). Six cats presented with anemia; two cats exhibited polycythemias, although this observation may also be consistent with dehydration in these patients. The cats were treated with Zarzio ® at a dose of 6 ug/kg for 3 consecutive days, based on dose administration previously reported using Neupogen ® in felines. Additionally, fluid therapy and supportive care were provided to relieve patients’ dehydration, vomiting and diarrhea.
Following Zarzio ® administration, CBCs was repeated on day 5. Results indicated that all patients were recovering with no need for supplementary dose of Zarzio ®. Results showed a statistically significant difference (p<0.01) in white blood cell count (WBC), with all parameters notably improved. However, red blood cells, hemoglobin, hematocrit and platelets parameters registered a notable reduction from day 1 to day 5 with a significant statistical difference (p < 0.01), considered as post-administration side effects.
One of the most important drugs in cancer therapy, human granulocyte colony stimulating factor (hG-CSF) filgrastim is a glycoprotein produced naturally by macrophages and other cells. Its medicinal properties include stimulating new blood cells and reducing the time to neutrophil recovery. Studies on human filgrastim in cats with FPL show promising results. Tests on healthy cats confirm the drug’s influence on hematopoiesis. Authors noted that filgrastim administration side effects included thrombocytopenia and anemia, also seen in prior feline studies and with human patients.
Limitations of this study include the small number of cats and lack of a control arm. Dose regimen employed was based on prior literature, and not on any kinetic or dynamic data. In addition, the high cost of the drug should also be taken into account when considering the utility of this therapeutic option.
All cats in this study survived and fully recovered from FPL, providing evidence for safety and efficacy of Zarzio ® in felines. Authors indicate that future studies should investigate the effect of this drug on platelet counts. The study was funded by the Iasi University of Life Sciences, Isai, Romania. ~GMA
See also:
Felix, N.; Vilela, C.L.; Niza, M.M.R.E. Clinical use of recombinant human granulocyte colony-stimulating factor in 7 cats with natural viral panleukopenia infection. Prat. Médicale Chir. Anim. Cie. 2005, 40, 71–76. [Google Scholar] doi: 10.5555/20053124692
Rice, J.K. Successful Treatment of Feline Panleukopenia: A Guideline for Rescuers and Veterinarians, Part I. J. Vet. Sci. Med. Diagn. 2017, 6, 2. doi: 10.4172/2325-9590.1000223
Kızılkaya, B.; Kara, E. The Effect of Granulocyte Colony Stimulating Factor Use in addition to Classical Treatment on Prognosis and Blood Values in Patients with Feline Panleukopenia. Kocatepe Vet. J. 2023, 16, 357–364. doi: 10.30607/kvj.1313752
Loya, K., Muhee, A., & Hussain, S. A. (2025). Effects of filgrastim on severe leucopenia associated with feline panleucopenia in cats. Applied Veterinary Research, 3(2), 2024009. https://doi.org/10.31893/avr.2024009