Gastroenteritis in young animals is a clinical presentation with many infectious and non- infectious aetiologies. We used next generation sequencing (NGS) to investigate the possible infectious causes of gastroenteritis in puppies from a dog kennel in Victoria, Australia. The near complete genome of a canine astrovirus was obtained from pooled faecal samples, and was found to be 94.7% identical with a canine astrovirus detected in the United Kingdom in 2012. The phylogenetic analysis of the capsid gene found similarities to those of canine astroviruses identified in Italy in 2005 and in UK and Hungary in 2012, but distant from that of a canine astrovirus previously identified in Australia in 2012. Thus, different serotypes of canine astrovirus are likely circulating in Australia. The close relationship to European astroviruses also suggested that there had been recent movements of ancestor canine astroviruses between Australia and Europe. NGS also detected other infections in the puppies including several canine papillomaviruses and a canine parvovirus (vaccine strain) as well as a very low level of campylobacter. Canine astrovirus was the probable cause of diarrhoea in these puppies, with the possible involvement of campylobacter bacteria. NGS was effective as a non-targeted method to determine the likely infectious cause of gastroenteritis.