Canine parvovirus type-2 (CPV-2) causes acute infectious diseases in puppies, which show high morbidity and mortality. Better effect of vaccination against these diseases could be achieved with deeper knowledge of CPV-2 genotype dissemination and mutation history. This study investigated CPV-2–positive samples collected recently over a wide region of China.

Canine parvovirus (CPV) disease is one of the most threatening to domestic and wild dogs.

Canine parvovirus (CPV) disease is one of the most threatening to domestic and wild dogs. A total of 132 clinical samples were isolated from domestic dogs with diarrhoea from Henan, Hubei, Jiangsu, and Anhui provinces from 2016 to 2017, and 56 were positive for CPV-2 by PCR. A phylogenetic tree was constructed for the isolate sequences incorporating 53 non-Chinese reference strains. VP2 sequences showed the strains mainly to be new CPV-2a/2b and CPV-2c genotypes. The Ala5Gly, Phe267Tyr, Ser297Ala, Tyr324Ile, Gln370Arg, Asn426Asp or Asn426Glu, and Thr440Ala sites in the VP2 protein antigenic region were found to have high mutation rates. The VP2 tertiary structural model shows that the change at these mutation points is a factor for the changes in the protein structure. Significant differences between the Central Chinese strains and others were found, indicating that evolution is geographically related and extended in major regions. The homology between the identified strains confirmed their relationship. Phylogenetic analysis indicated that the common genotypes in the same clusters differ slightly in homology and evolutionary history. This epidemiological study enriches the available data and serves as an important reference for studies on the evolution of CPV and selection of vaccines in China.

Canine parvoviral enteritis (CPVe) is an important infectious disease that has pretty high morbidity and mortality rates in puppies, which leads to vomiting and diarrhea range from mucoid to hemorrhagic. The objective of this study to investigate the changes in erythrocyte osmotic fragility (EOF) and hematological parameters in dogs with CPVe. Sixteen healthy and twenty-seven infected male and female dogs identified by the CPV antigen rapid-test kit at ages 2-6 months old were used to collect blood samples. A complete blood count and EOF were measured from the samples. Findings of hemogram showed that WBC, RBC, and HCT values were significantly lower in infected dogs (the p-value of the first one is p<0.001, other two ones are p<0.05) compared to healthy controls. The infected dogs had non-significantly lower NEU, EOS, and PLT values, and higher LYM, MON, MCV, MCH, and MCHC values than control group (p>0.05). Although the hemolysis rate of infected dogs' erythrocytes at the concentrations of 0.4 - 0.1 % NaCl were higher than that of healthy dogs, this difference was statistically significant at only 0.3% NaCl (p<0.05). In addition, the median corpuscular fragility (MCF), equal to the NaCl concentration that lyses 50% of erythrocytes, of dogs with CPVe (0.42%) was higher than the MCF values of the control group (0.39%), but not statistically significant (p>0.05). In conclusion, besides the hematological findings revealed that WBC, RBC, and HCT values were significantly lower in dogs with CPVe than that in healthy dogs in this study, it was reported for the first time that canine parvovirus significantly increased osmotic fragility of RBCs at 0.3 % NaCl concentration compared to the control group. We concluded that to consider of these, particularly affected, blood parameters may be useful for determining the prognosis of CPVe.

A four-month-old male Labrador retriever puppy was presented to Referral Veterinary Polyclinic, Indian Veterinary Research Institute with the history of anorexia, vomiting, haemorrhagic diarrhoea and signs of hypovolaemic shock. The case was diagnosed as parvovirus gastroenteritis by rapid antigen detection test. Shock was managed by infusion of polyionic isotonic fluid.  Haematological examination revealed severe leukopenia with WBC count of 0.3×10³/µL, which was treated with administration of recombinant human granulocyte colony stimulating factor (Filgrastim) at 5 mcg/kg subcutaneously along with supportive therapy. Dog showed elevated WBC count and improvement in clinical signs after 48 h. Administration of granulocyte colony stimulating factor along with routine therapy enhanced the survivability in canine parvovirus gastroenteritis.

After the original identification of canine parvovirus (CPV) type 2 (CPV-2) in 1978, new antigenic variants such as CPV-2a, CPV-2b and CPV-2c have become widespread in the most countries. In this study, the genetic analysis of canine parvovirus was investigated in a total of 13 CPV vaccines, which have been licensed in Korea since late 1980s, and a field isolate of CPV from a dog with CPV infection clinical symptom. The partial VP2 gene of CPV was amplified and sequenced from 13 vaccine strains and one field isolate. The results showed that of the 13 vaccine strains, 10 strains belong to the CPV-2, 2 strains to CPV-2b, the remaining and one isolate to CPV-2a type, respectively. Several mutations of amino acids were detected at residues of the critical region of the commercial vaccine strains. These data suggest that new type of vaccines containing CPV-2a or CPV-2b/2c type may be required for the better prevention of new CPV infection in dog population in Korea, because CPV-2 contained in most licensed vaccines has been replaced by antigenic variants designated CPV-2a or CPV-2b/c in the worldwide dog population.

Rapid immunochromatography test (RICT) kits are commonly used for the diagnosis of canine parvovirus (CPV) because of their rapid turnaround time, simplicity, and ease of use. However, the potential for cross-reactivity and low sensitivity can yield false-positive or false-negative results. There are 4 genotypes of CPV. Therefore, evaluating the performance and reliability of RICT kits for CPV detection is essential to ensure accurate diagnosis for appropriate treatment. In this study, we evaluated the performance of commercial RICT kits in the diagnosis of all CPV genotypes. The cross-reactivity of 6 commercial RICT kits was evaluated using 8 dog-related viruses and 4 bacterial strains. The limit of detection (LOD) was measured for the 4 genotypes of CPV and feline panleukopenia virus. The tested kits showed no cross-reactivity with the 8 dog-related viruses or 4 bacteria. Most RICT kits showed strong positive results for CPV-2 variants (CPV-2a, CPV-2b, and CPV2c). However, the 2 kits produced negative results for CPV-2 or CPV-2b at a titer of 105 FAID50/mL, which may result in inaccurate diagnoses. Therefore, some kits need to improve their LOD by increasing their binding efficiency to detect all CPV genotypes.

A total of 128 faecal samples of dogs suspected for canine parvovirus infection were examined by Haemagglutination (HA) and Haemagglutination inhibition (HI) tests. The prevalence of canine parvovirus infection was 45.30% (58/128) and the age wise maximum (70.20%) prevalence was found in dogs upto 6 month. The breed wise maximum (56.90%) prevalence was in Non-descript dogs and sex wise prevalence revealed no significant difference in male (45.9%) and female (43.3%).