Background. Canine parvovirus (CPV-2) is the number one cause of mortality in young puppies. CPV-2 infection is an emerging problem of puppies in the USA despite vaccination. CPV-2 undergoes mutations at hot spots of the viral protein-2 (VP-2). Thus, continuous monitoring of CPV-2 genotypes is required.

Methods. A PCR-based was used to genotype the CPV-2 samples submitted during the period of 2006-2012 to OADDL. The genotype of the CPV-2 was assigned based on the codon (CPV-2c= GAA; CPV-2b=GAT) at position 426 of the VP-2.

Results. Small intestine and tongue tissue samples were first screened for CPV-2 using direct fluorescent antibody test (FAT using 3BA10, anti canine parvovirus-FITC conjugate, VMRD, WA, USA). A high agreement was observed between the positive and negative FAT results on both the tissues were examined on the same puppy. Tissue and feces samples were CPV-2 genotyped using PCR followed by sequencing. CPV-2b and CPV-2c were the most common in the USA. Codon 440 of VP-2 was studied and an increase in frequency of change from ACA with GCA was also observed.

Conclusions. Both tongue and intestines are suitable for detection of CPV-2 infection. Frequency of mutations of the two major surface exposed amino-acids (426 and 440) present in the major antigenic epitopes of CPV-2 VP-2 is increasing in the USA. Thus, the efficacy of current commercial CPV-2 vaccines needs to be experimentally verified using the current emerging isolates of CPV-2c¹ .