Feline panleukopenia (FPL) is a very common clinical disease syndrome in cats caused by infection with Carnivore protoparvovirus-1, it is also the oldest known viral disease in cats. Both feline parvovirus (FPV) and canine parvovirus (CPV-2) can cause FPL. Kittens usually die within the mortality rate of 90% despite vaccination. So far no research on CPPV-1 prevalence and epizootiology in cats in the Republic of Croatia has been done. The aim of this study was: 1) To collect the data on the prevalence of CPPV-1 strains on the territory of the Republic of Croatia, to determine risk factors and clinical manifestations of infection to facilitate the identification of infection and targeted treatment by veterinary practitioners. 2) Phylogenetic analysis of the virus, which has not been conducted in our country so far to provide insight into the molecular epizootiology of infection with feline panleukopenia. 3) Determining the direction of CPPV-1 evolution in cats and the significance of the amino acid alterations of viral proteins for the pathogenicity and efficacy of immunoprophylaxis. MATERIAL AND METHODS During the period from 2015 to 2020, 211 rectal swabs and fecal samples of cats that showed signs of acute gastroenteritis were collected from the Clinic for Infectious Diseases of the Faculty of Veterinary Medicine, University of Zagreb. Along with the fecal samples, data on medical history, clinical picture, course, and treatment outcome were collected for all the animals included in this study. The presence of CPPV-1 strains in fecal samples or rectal swabs was detected with the polymerase chain reaction. Determination of the nucleotide sequence of amplified sections of the genome was done by MEGA 7 software. RESULTS The overall prevalence of feline panleukopenia in cats that showed clinical signs of acute gastroenteritis in the city of Zagreb was 61.61% with a survival rate of 55,55%. It was proven that both strains of CPPV-1 were present in the cat population in the city of Zagreb (FPV=73.33%, CPV-2=22.67%). Furthermore, CPV-2c virus type was shown to dominate with 76.47%, while CPV-2c was found in 11.76% of samples and 11,76% had no results of virus type. Data on the disease history collected during the first examination revealed that younger animals were more likely to be infected with the FPV strain (average of 0.79 years), while the CPV-2 strain was more common in older animals (average of 4.5 years). CBC showed statistically significant eosinopenia as well as significantly reduced platelet counts in positive cats. In FPV strains, amino acid changes were found at positions 91, 232, 303 (receptor binding sites) and position 562 which might indirectly cause surface conformational changes. Phylogenetic analysis of the tree gave us two large groups, local and international, which can be explained by a universal model of evolution caused by globalization, that makes strains from different continents similar to each other. CONCLUSIONS The prevalence of 61,61% of CPPV-1 in the city of Zagreb was high and it was consistent with all the published results in other countries. The percentage of CPV-2 strains (22,67%) among the positive samples was higher than expected. Significant eosinopenia, as well as significantly reduced platelet counts in the CBC of positive cats, could serve for diagnostic purposes. In FPV strains, amino acid changes were found at positions 91, 232, 303, and 562. Amino acid residues 91, 232, and 303 are antibody binding sites, while amino acid residue 562 might indirectly cause surface conformational changes. Phylogenetic analysis of the tree provided insight into the distribution of sequences into two large groups, local and international, which can be explained by the existence of a universal model of evolution as a result of globalization, so strains from different continents are similar to each other.